tag:blogger.com,1999:blog-35617981152159341652024-03-12T20:53:25.221-04:00bicycle lightingoddly obsessed with dynamo powered bicycle lightsminisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-3561798115215934165.post-88591591033251988742012-10-25T10:12:00.004-04:002012-10-25T10:13:51.868-04:00A brief hiatus and the generosity of strangers<div class="separator" style="clear: both; text-align: center;">
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I'm feeling mildly sheepish about the dearth of posts here over the last few months. After the initial flurry of interest about the Nº58A I ran into some technical issues with the prototype that took a couple of months and several rebuilds to solve. I got a working version on my bike at the end of July, took it for <a href="https://twitter.com/bicilux/status/229781934513999872" target="_blank">one night ride</a> and then went on vacation for a month. I've had it out a few times since, although my night rides are few and far between these days. So far, so good. The size is appealing and while pretty heavy, it seems to be surviving mounted on a Schmidt 4 mm wire bracket over the fork crown without pitching forward:<br />
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I also spent a long time designing an elegant two-piece sheet metal bracket for a front-rack hanging version. I was very pleased with the result, but then got a quote for the tooling costs to produce said bracket and my enthusiasm was quashed.<br />
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<tr><td class="tr-caption" style="text-align: center;">Nº58B hanging bracket design</td></tr>
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Further dampening my enthusiasm is the fact that I'm still not convinced that a production run of Nº58As is worthwhile without a cutoff reflector that produces a shaped beam. I know a lot of speciality bike lights, especially the infamous <a href="http://magicshineusa.com/" target="_blank">MagicShine</a> series of lamps, have wide, symmetrical flashlight-like beams, but <a href="http://janheine.wordpress.com/" target="_blank">aficionados</a> (to which I aim to appeal) tend to overwhelmingly favor a shaped beam that directs the light down and ahead, onto the road. Unfortunately, there is no known off-the-shelf solution, which leads down the increasingly unfeasible road to custom reflector design and fabrication. If you feel strongly either way about what kind of reflector you'd like to see in the Nº58A, please weigh in with your comments.<br />
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Also, a nice headlight deserves a matching taillight, which I've also spent a good deal of time designing. Unfortunately, prototyping a plastic lens is not as affordable or facile as CNC machining aluminium. I've been frustrated by the cost to get a red-tinted lens prototype fabricated for a matching taillight. Even 3D-printing methods approach the cost of the entire Nº58A prototype to get a single lens with sufficient detail and acceptable colouring, transparency and finish. And, of course, the taillight has an elegant but unaffordable formed sheet metal bracket:<br />
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<tr><td class="tr-caption" style="text-align: center;">JOS FU-inspired taillight design</td></tr>
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On top off all that, my development budget is spent for now. And finally, while waiting for the headlamp prototype to arrive, I completely immersed myself in another, unrelated electronics <a href="http://prophet600.blogspot.ca/" target="_blank">project</a>.<br />
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That said, I do intend to push forward when money and time allow, although perhaps at a more considered rate than I had first hoped.<br />
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In lighter news, a generous reader from the UK (thanks Andy!) offered me a couple of Sturmey Archer GH6s he found whilst cleaning his garage. They took a circuitous route from the UK to Toronto to avoid prohibitive international shipping charges and I finally picked them up from my rusty-bicycle-hub mule yesterday:<br />
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One's an '82 and the other's a '51. They now await lots of tinfoil elbow grease. Might be time to build a new bike around an old Dynohub!<br />
<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com3tag:blogger.com,1999:blog-3561798115215934165.post-60346417434181470952012-06-27T11:59:00.002-04:002012-06-27T11:59:39.662-04:00Nº58A Glamour Shots<div class="separator" style="clear: both; text-align: center;">
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Reception to my first post about the<a href="http://minisystem.blogspot.ca/2012/06/n58a-bicycle-light-first-prototype.html" target="_blank"> Nº58A front lamp prototype</a> has been great, especially after <a href="https://twitter.com/#!/Velo_Orange" target="_blank">Chris@Velo_Orange</a> <a href="https://twitter.com/Velo_Orange/status/213279229348024321" target="_blank">tweeted</a> about it. While waiting for a proper copper heat sink to arrive (and for quotes for a front rack hanging version) I got a new camera that takes nicer photos than my point and shoot. In an effort to learn how it works, I took a series of shots of the Nº58A prototype mounted on my orange bike. The full set is on <a href="http://www.flickr.com/photos/bicilux/sets/72157630314755666/" target="_blank">Flickr</a>.<br />
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<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com2tag:blogger.com,1999:blog-3561798115215934165.post-13984308788510245592012-06-15T16:18:00.000-04:002012-06-15T18:33:56.941-04:00BICI LUX now on Twitter<div class="separator" style="clear: both; text-align: center;">
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I've never been much of a Twitter user, evidenced by the sparse tweets on my <a href="http://twitter.com/minisystem" target="_blank">music-related account</a>. However, Chris was nice enough to link to the <a href="http://minisystem.blogspot.ca/2012/06/n58a-bicycle-light-first-prototype.html" target="_blank">Nº58A prototype</a> in the <a href="http://twitter.com/velo_orange" target="_blank">Velo Orange Twitter feed</a> yesterday, which got the attention of a bunch of folks who probably otherwise wouldn't wind up on such an obscure and esoteric corner of the internet. This got me thinking that it was about time to set up an account for <a href="http://bicilux.com/" target="_blank">Bici Lux</a>. Tweets will likely be few and far between, but I'll probably link to the occasional notable Ebay auction and may tweet out the minutia of designing, engineering and prototyping. So, follow me if you like. It might encourage me to tweet more. <a href="http://twitter.com/bicilux">twitter.com/bicilux</a>.minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0tag:blogger.com,1999:blog-3561798115215934165.post-45287222294888894772012-06-13T12:30:00.000-04:002012-06-15T08:57:14.003-04:00Nº58A bicycle light: first prototype<div class="separator" style="clear: both; text-align: center;">
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After an agonizing three month wait (quality budget machinists are busy machinists and never send anything you greatly anticipate through regular mail from Australia to Canada), the parts for the first Nº58A prototype arrived. It was back in February that I first posted about <a href="http://minisystem.blogspot.ca/2012/02/new-bicycle-headlamp-design-philosophy.html">designing a new classically styled bicycle headlight</a> and the prototype was ordered in March.<br />
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While I was waiting, I designed and ordered the PCBs for the LED board (with low loss FET rectifier) and stand light board. When they arrived I assembled and tested them. The circuit is very similar to the <a href="http://minisystem.blogspot.ca/2011/12/flashing-dynamo-light-prototype.html">dynamo standlight </a>I designed for the <a href="http://minisystem.blogspot.ca/2012/04/sturmey-archer-light-set-led-upgrade.html">Sturmey Archer headlamp LED upgrade</a>. It took me a while to find the time to solder the LED to the heat sink, connect the LED and stand light boards and assemble the whole thing into the housing. After fawning over its shininess for a few days, I took a few photos with my lousy point and shoot:<br />
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<tr><td class="tr-caption" style="text-align: center;">Second hole is for a taillight connection</td></tr>
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Right off the bat, there were a couple of problems. The first was that the machinist's supplier substituted brass for the C101/C110 pure copper that was ordered for the heat sink This is a pretty sloppy and annoying transgression for which I was assured the supplier was sufficiently chastised (though it would've been nice if the operator had noticed that he was working with brass when pure copper was specified). Brass is fine for soldering LEDs to but its thermal properties make it unacceptable as an efficient heat sink. Consequently, it took a lot longer to solder the LED as brass isn't nearly as good a conductor of heat as pure copper. For the prototype it should be fine, but I'll need to make sure the heat sink is copper for the next revision.<br />
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The second problem is that a slight widening at the opening of the lamp body that was specified in the CAD files wasn't machined. Due to confusion about the female threading it was omitted on the final drawings by mistake and I didn't notice. This widening was to accomodate an o-ring for weather-proofing and without it the o-ring doesn't fit. Again, the next revision will need to have this step cut for the o-ring.<br />
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I've had several people suggest making a hanging version that can be mounted on a front rack. This, which will likely be christened the Nº58B, is in the works. In the meantime, the current version is designed to be mounted over the fork crown. Its weight dictates that a heavy duty bracket be used, something like the <a href="http://www.sjscycles.co.uk/schmidt-headlight-bracket-for-edelux-prod23928/">4 mm wire bracket offered by Schmidt</a>. Using this bracket, I mounted it on one of my bikes (enjoy the reflections of my living room):<br />
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<a href="http://4.bp.blogspot.com/-fceSK0gfQBo/T9eBhJd8FmI/AAAAAAAAEK8/P1rxe-wlVPA/s1600/IMG_5627.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://4.bp.blogspot.com/-fceSK0gfQBo/T9eBhJd8FmI/AAAAAAAAEK8/P1rxe-wlVPA/s640/IMG_5627.JPG" width="640" /></a></div>
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<a href="http://4.bp.blogspot.com/-2On7hSNWMJk/T9eCU-TUCUI/AAAAAAAAELg/mFYMw399Mu8/s1600/IMG_5635.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://4.bp.blogspot.com/-2On7hSNWMJk/T9eCU-TUCUI/AAAAAAAAELg/mFYMw399Mu8/s640/IMG_5635.JPG" width="480" /></a></div>
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Full set is available on <a href="http://www.flickr.com/photos/bicilux/sets/72157630115304378/">Flickr</a>.</div>
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Overall, I'm quite pleased with the results. Everything fits together as it should, with the exception of the bezel's o-ring. I fretted about the location of the switch, but I don't think it's an unacceptable interruption to the lamp's shape. I might try a full switch boot instead of the half boot pictured or perhaps a switch with a shorter actuator.</div>
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With a few modifications, this could be ready for a production run if there's enough interest. Before that, I'd like to get the front rack hanging version made and log some serious hours to flush out any design flaws. An asymmetrical version would be nice as the round, flashlight-like beam of the current reflector certainly won't meet the <a href="http://swhs.home.xs4all.nl/fiets/tests/verlichting/stvzo/index_en.html">StVZO rules for bicycle lighting</a>. However, for small volume production it seems unlikely that a custom engineered asymmetrical reflector with cutoff will be viable.</div>
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Beam shots? Not yet. I personally don't find them very informative, so they are a lower priority. Plus, the LED tested out OK after assembling the lamp, but a few days later it was dead, so I need to replace it which requires waiting for a revised heat sink to get machined. Hopefully this was just an unlucky failure due to the excessive heat required to solder it to the brass heat sink and not because of a systemic design problem. Only testing on the bike will tell...minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com5tag:blogger.com,1999:blog-3561798115215934165.post-80104736043134086572012-06-12T23:33:00.000-04:002012-06-13T09:33:23.069-04:00A new look for Bicycle LightingJust a quick note to say that it was time for a little blog layout upgrade to something a little more... contemporary. My HTML days are long behind me and I don't even know what the web runs on nowadays so I had to rely on the fine skills of a friend who wishes to remain anonymous. My thanks to you, whoever you are.<br />
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Vintage lighting aficionados will recognize the logo as the armature faceplate of my favorite hub dynamo of all time, the <a href="http://www.bicyclehub.co.uk/index.php?option=com_content&view=article&id=46&Itemid=108">Sturmey Archer GH6 Dynohub</a>.<br />
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Sorry Windows users, without <a href="http://en.wikipedia.org/wiki/Helvetica#Neue_Helvetica_.281983.29">Helvetica Neue Light</a> you're really missing out.minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0tag:blogger.com,1999:blog-3561798115215934165.post-51428934773577343312012-05-08T23:14:00.000-04:002012-05-08T23:14:41.037-04:00JOS, Radios, Luxor Ebay bonanzaI <a href="http://minisystem.blogspot.ca/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">like</a> <a href="http://minisystem.blogspot.com/2011/12/vintage-radios-bicycle-lamps.html">vintage French</a> <a href="http://minisystem.blogspot.com/2012/02/classic-bicycle-taillights.html">bicycle lights</a>. So much so, that one of my saved searches on Ebay is '(luxor, radios, soubitez, JOS)' in the Vintages Parts & Accessories category. Today, this search has yielded an unusual bonanza of beautiful, often new-old-stock (NOS) items. I don't know anything about the vintage French bicycle accessory market, but there seem to be a <a href="http://myworld.ebay.com/1649philippe/">few</a> <a href="http://myworld.ebay.com/rocvale/">French</a> <a href="http://myworld.ebay.com/bike-france/">Ebay</a> sellers that frequently list some highly desirable lights. I assume these guys pick them up for a song and then sell the choice ones for a small fortune (JOS lamps can easily fetch several hundred dollars). I don't know where this seemingly endless supply of NOS JOS/Luxor/Radios lamps is sourced from, but I'm mildly suspicious that it is some kind of racket where supply is tightly controlled to drive up prices. The frequency of NOS JOS 431 headlamp and FU tail lamp listings borders on conspiratory.<br />
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While most of these lights are way out of my budget, I do admire the often beautiful photography and feel that the images have an important archival quality that exceeds that of the <a href="http://homepage3.nifty.com/ClassicBicycles/brands/brands.html">two</a> <a href="http://www.blackbirdsf.org/index4.html">sites</a> I know of that document vintage French lamps. High quality Ebay listing photos are inherently ephemeral, so I wanted to provide a more permanent home for some of the really nice lamps that have turned up on Ebay France in the last few weeks. I won't link to the auctions on Ebay, as they themselves are eventually lost in the ether. The main sellers whose images I'm using are <a href="http://myworld.ebay.com/1649philippe/">1649philippe</a> and <a href="http://myworld.ebay.com/rocvale/">rocvale</a> (the latter of which has a cool <a href="http://www.velorama.fr/">site</a> and <a href="http://la-bicyclette.over-blog.com/">blog</a>). Should they have a problem with it, I encourage them to contact me (email at the bottom of the page), although this post will most likely work in some small way to their advantage by furthering the fetishization of their wares! Here they are:<br />
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JOS 431C. This is the holy grail for restorers of <a href="http://www.cycles-alex-singer.fr/">Alex Singer</a> touring/randonneuring bicycles. These diminutive headlights, usually mounted on the front fender/mudguard, can command anywhere from $200-400! This one is NOS, although with a lot of noticeable shop wear:<br />
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<a href="http://3.bp.blogspot.com/-k4EgbeWCONs/T6nVUFzdBGI/AAAAAAAAD8k/sWltEKwBfag/s1600/JOS+431+1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://3.bp.blogspot.com/-k4EgbeWCONs/T6nVUFzdBGI/AAAAAAAAD8k/sWltEKwBfag/s640/JOS+431+1.jpg" width="640" /></a></div>
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<a href="http://1.bp.blogspot.com/-Sa0yc6wT51Q/T6nVV-KObnI/AAAAAAAAD8s/opWX89j8Xt4/s1600/JOS+431+2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://1.bp.blogspot.com/-Sa0yc6wT51Q/T6nVV-KObnI/AAAAAAAAD8s/opWX89j8Xt4/s640/JOS+431+2.jpg" width="640" /></a></div>
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<a href="http://3.bp.blogspot.com/-tBVIgGp91Vo/T6nVXvd8QgI/AAAAAAAAD80/1Ow41TNpZBo/s1600/JOS+431+3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://3.bp.blogspot.com/-tBVIgGp91Vo/T6nVXvd8QgI/AAAAAAAAD80/1Ow41TNpZBo/s640/JOS+431+3.jpg" width="640" /></a></div>
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JOS FU and FUA taillights. The charming taillight with the slightly less charming name, it is often paired with the 431 headlight. Typically, the FU/As are mounted on a braze-on on the left chain stay, like <a href="http://static.flickr.com/59/156578523_6029587067.jpg">this</a> and <a href="http://www.symphonic-net.com/france1961/My%20Pictures/otake-singer/t_singer-2007%200148.jpg">this</a>. Prices are similarly ridiculous ($100-$400+):</div>
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<a href="http://1.bp.blogspot.com/-JGcGOSAxHJw/T6nVaN0mYpI/AAAAAAAAD9E/pvomEBbcVAs/s1600/JOS+FU+1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://1.bp.blogspot.com/-JGcGOSAxHJw/T6nVaN0mYpI/AAAAAAAAD9E/pvomEBbcVAs/s640/JOS+FU+1.jpg" width="640" /></a></div>
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<a href="http://2.bp.blogspot.com/-09t0ctQKwpI/T6nVdJMH4VI/AAAAAAAAD9M/zd_aXGWmZXA/s1600/JOS+FU+2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://2.bp.blogspot.com/-09t0ctQKwpI/T6nVdJMH4VI/AAAAAAAAD9M/zd_aXGWmZXA/s640/JOS+FU+2.jpg" width="640" /></a></div>
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<a href="http://3.bp.blogspot.com/-xlDKeM05JFw/T6nVpUZbf5I/AAAAAAAAD-8/M5GBMyGIfyQ/s1600/JOS+FUA+1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="402" src="http://3.bp.blogspot.com/-xlDKeM05JFw/T6nVpUZbf5I/AAAAAAAAD-8/M5GBMyGIfyQ/s640/JOS+FUA+1.jpg" width="640" /></a></div>
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<a href="http://4.bp.blogspot.com/-RJQMs-UCdEo/T6nVp-30YVI/AAAAAAAAD_E/JBjMHoQgRYk/s1600/JOS+FUA+3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="392" src="http://4.bp.blogspot.com/-RJQMs-UCdEo/T6nVp-30YVI/AAAAAAAAD_E/JBjMHoQgRYk/s640/JOS+FUA+3.jpg" width="640" /></a></div>
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RADIOS Nº16 headlamp. This is a slightly smaller version of the <a href="http://minisystem.blogspot.com/2011/12/vintage-radios-bicycle-lamps.html">RADIOS Nº18</a>. A relative bargain at $75-$200:</div>
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<a href="http://2.bp.blogspot.com/-9U1TyCCO-0U/T6nVkvPjxwI/AAAAAAAAD-E/z6tA8IBX82k/s1600/Radios16_2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="462" src="http://2.bp.blogspot.com/-9U1TyCCO-0U/T6nVkvPjxwI/AAAAAAAAD-E/z6tA8IBX82k/s640/Radios16_2.jpg" width="640" /></a></div>
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<a href="http://4.bp.blogspot.com/-dGTKbMnj_JU/T6nVlce-v0I/AAAAAAAAD-M/wfHGgW-0X1M/s1600/Radios16_3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="356" src="http://4.bp.blogspot.com/-dGTKbMnj_JU/T6nVlce-v0I/AAAAAAAAD-M/wfHGgW-0X1M/s640/Radios16_3.jpg" width="640" /></a></div>
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RADIOS taillights. I don't know much about them, but they are pretty spectacular:</div>
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<a href="http://4.bp.blogspot.com/-Bsfi4SmbF-c/T6nVjvhYC1I/AAAAAAAAD90/aSBclUHb5zY/s1600/RadiosDrop_a.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="390" src="http://4.bp.blogspot.com/-Bsfi4SmbF-c/T6nVjvhYC1I/AAAAAAAAD90/aSBclUHb5zY/s640/RadiosDrop_a.jpg" width="640" /></a></div>
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<tr><td class="tr-caption" style="text-align: center;">RADIOS droplet fender-mounted taillight</td></tr>
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<a href="http://3.bp.blogspot.com/-FVsqlCQIMwI/T6nVmshwolI/AAAAAAAAD-c/lWhZN4BA4Dw/s1600/Radios+taillight+1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="420" src="http://3.bp.blogspot.com/-FVsqlCQIMwI/T6nVmshwolI/AAAAAAAAD-c/lWhZN4BA4Dw/s640/Radios+taillight+1.jpg" width="640" /></a></div>
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Finally, no sonnet to French lights would be complete without mention of my personal favorite, the Luxor series. The Ebay listings are a little light right now, but here is a really nice example of the 'Le Paon' fender-mounted taillight:<br />
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<a href="http://3.bp.blogspot.com/-wFTfz0XjrIQ/T6nVsG0fDEI/AAAAAAAAD_c/S_gdfJCU33A/s1600/LuxorPaon_b.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="http://3.bp.blogspot.com/-wFTfz0XjrIQ/T6nVsG0fDEI/AAAAAAAAD_c/S_gdfJCU33A/s640/LuxorPaon_b.jpg" width="640" /></a></div>
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<a href="http://2.bp.blogspot.com/--ZZ6dsOvGuc/T6nVs8dsFlI/AAAAAAAAD_k/wrtlFzsravs/s1600/LuxorPaon_a.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="414" src="http://2.bp.blogspot.com/--ZZ6dsOvGuc/T6nVs8dsFlI/AAAAAAAAD_k/wrtlFzsravs/s640/LuxorPaon_a.jpg" width="640" /></a></div>
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<a href="http://2.bp.blogspot.com/-sQigBxTwW1E/T6nVtLxH70I/AAAAAAAAD_s/Fabkxu5ct_o/s1600/LuxorPaon_c.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="356" src="http://2.bp.blogspot.com/-sQigBxTwW1E/T6nVtLxH70I/AAAAAAAAD_s/Fabkxu5ct_o/s640/LuxorPaon_c.jpg" width="640" /></a></div>
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I'm a personal fan of the 'Le Martele' <a href="http://www.flickriver.com/photos/10703870@N06/sets/72157624583329882/">hammered Luxor lights</a>, and even <a href="http://minisystem.blogspot.ca/2011/09/back-to-workbench.html">own a set</a>, which I've been busy trying to <a href="http://minisystem.blogspot.com/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">upgrade with LEDs</a>. Now I just need to find a bike to put them on...minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com2tag:blogger.com,1999:blog-3561798115215934165.post-80041572880055117462012-04-30T09:42:00.002-04:002012-04-30T09:42:36.871-04:00A personal masterpiece: Raleigh Sprite 3-speed conversion with retro lights!<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-iycw3FnAqAw/T5wlrx4iDQI/AAAAAAAAD1A/UbwQ2CMNj6E/s1600/_DSC0568.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="424" src="http://2.bp.blogspot.com/-iycw3FnAqAw/T5wlrx4iDQI/AAAAAAAAD1A/UbwQ2CMNj6E/s640/_DSC0568.JPG" width="640" /></a></div>
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This is it, my most finicky and obsessive bike project thus far: a 3-speed conversion of a 1980s <a href="http://sheldonbrown.com/retroraleighs/sprite.html">Raleigh Sprite</a> with <a href="http://minisystem.blogspot.ca/2012/04/sturmey-archer-light-set-led-upgrade.html">LED-equipped vintage lampset</a>. My <a href="http://www.flickr.com/photos/shapelike/2238341112/lightbox/">Motobecane city bike project</a> was considerably higher end, but it wasn't done by my hands and, crucially, doesn't have a lighting system. It's been a full year in the making (I ordered the wheelset on April 27, 2011), but most of the time was spent <a href="http://minisystem.blogspot.ca/2011/12/flashing-dynamo-light-prototype.html">developing the LED lighting system</a>. First, a bit of history:<br />
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Canadian-made Raleigh Sprites are quite a common sight on the streets of Toronto. The most popular colour seems to be black, but there are gorgeous candy apple red ones that I see quite often as well. The ladies Sprite had a true double-toptube Mixte frameset, very elegant and in contrast to the single sloping toptube of earlier Raleigh ladies models. The original configuration of the 1980s Sprites was a 5-speed complete with matching fenders and a classic <a href="http://www.bonniebikes.com/pletscher-rear-rack-cs---optional-extra-494-p.asp">Pletscher CS rack</a>. This particular Sprite was my mom's, purchased sometime in the early-mid 1980s. She didn't ride it much and it spent most of its life in the musty basement of an old stone shed. It had some regular use sometime in the late-nineties to early-naughts by a family friend, who treated it to its only tune up. Sometime in the last decade the front wheel got smushed and it became officially derelict. I've had my eye on it for a couple of years as a new bike to build up for my wife.<br />
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Last spring, I pulled it out of the damp basement, stripped it of its old wheels, handlebars, brake levers, pedals and saddle, gave the frame a good cleaning and polished up the Shimano Tourney brakeset, SR Stem and Silstar crank arms with <a href="http://velo-orange.blogspot.ca/2012/04/polishing-with-simichrome.html">Simichrome</a>. I then set to work with converting it to a 3-speed. I'm particularly fond of the <a href="http://minisystem.blogspot.ca/2011/09/ode-to-raleigh-superbe-and-its-dynohub.html">Raleigh Superbe,</a> and it is the Superbe's 3-speed/Dynohub combination that served as my inspiration for upgrading this Sprite.<br />
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<a href="http://1.bp.blogspot.com/-4ykd_Kjb3Q4/T5wlOLuXUFI/AAAAAAAAD3U/geVBIRy4K0k/s1600/_DSC0554.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="425" src="http://1.bp.blogspot.com/-4ykd_Kjb3Q4/T5wlOLuXUFI/AAAAAAAAD3U/geVBIRy4K0k/s640/_DSC0554.JPG" width="640" /></a><br />
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<a href="http://4.bp.blogspot.com/-svMWi-8TvKQ/T5wlpVFDeLI/AAAAAAAAD04/7L6jn5rtSB8/s1600/_DSC0565.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://4.bp.blogspot.com/-svMWi-8TvKQ/T5wlpVFDeLI/AAAAAAAAD04/7L6jn5rtSB8/s640/_DSC0565.JPG" width="480" /></a></div>
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First, I ordered a wheel set from <a href="http://www.longleafbicycles.com/">Longleaf Bicycles</a>, who provide a very high quality and inexpensive <a href="http://www.longleafbicycles.com/custom-wheelbuilding/">custom wheel building service</a>. A <a href="http://www.longleafbicycles.com/products/components/wheels-hubs-rims-spokes-etc/hubs/internally-geared-hubs/sturmey-archer-internal-gear-hubs-and-parts/sturmey-archer-3-speed-hub-srf3/">Sturmey Archer SRF3</a> three-speed hub and <a href="http://www.longleafbicycles.com/products/dynohubs-and-lighting/dynohubs/sanyo-dynohubs/">Sanyo H27 </a>dynamo hub are laced to <a href="http://store.velo-orange.com/index.php/components/wheelsets-rims-hubs/rims/vo-pbp-700c-rims.html">Velo Orange 36 hole PBP rims</a>. The only problem is that the original wheels were 27", causing a problem with <a href="http://sheldonbrown.com/calipers.html">brake reach</a> for the handsome Shimano Tourney callipers on the rear wheel; they barely had enough reach with the original wheel diameter. Not wanting to have to purchase new longer reach brakes, I had my first part CNC-machined: a drop bolt to lower the rear brake so that its arms have enough reach:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Qollji_OaaQ/T5wxZ9y3FJI/AAAAAAAAD30/tQwxndKXrI0/s1600/dropbolt.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="531" src="http://4.bp.blogspot.com/-Qollji_OaaQ/T5wxZ9y3FJI/AAAAAAAAD30/tQwxndKXrI0/s640/dropbolt.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Brake drop bolt for mixte frame</td></tr>
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It works nearly perfectly and is very discrete:<br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-txwimad8qbo/T5wmAK5UQ1I/AAAAAAAAD1g/x4py-5eX6Mg/s1600/_DSC0583.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="424" src="http://4.bp.blogspot.com/-txwimad8qbo/T5wmAK5UQ1I/AAAAAAAAD1g/x4py-5eX6Mg/s640/_DSC0583.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Inconspicuous drop bolt</td></tr>
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The only problem is that it takes up a bit of space that the fender could have used, resulting in a really tight fit. A future revision would have beveled the edge that comes into contact with the fender.<br />
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With the brake reach problem sorted, I went about setting up the handlebars (<a href="http://store.velo-orange.com/index.php/components/handlebars/vo-tourist-handlebar-22-2-dia.html">VO Tourist</a>) with the 3-speed trigger shifter and brake levers. I tried the original levers but they didn't fit with the shifter. I had a pair of ridiculously expensive <a href="http://www.paulcomp.com/lovelever25.html">Paul Love Levers</a> lying around from another project that fit perfectly:<br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Rr2haecZqyg/T5wm2ZSdqqI/AAAAAAAAD14/lUVIFoF8xsk/s1600/_DSC0597.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="424" src="http://4.bp.blogspot.com/-Rr2haecZqyg/T5wm2ZSdqqI/AAAAAAAAD14/lUVIFoF8xsk/s640/_DSC0597.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">3-speed trigger shifter with Paul Love Levers</td></tr>
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<a href="http://4.bp.blogspot.com/-k9K96W59lok/T5wm9JoOV-I/AAAAAAAAD2I/e0a9grXRfYE/s1600/_DSC0600.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://4.bp.blogspot.com/-k9K96W59lok/T5wm9JoOV-I/AAAAAAAAD2I/e0a9grXRfYE/s640/_DSC0600.JPG" width="478" /></a></div>
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The new Sturmey Archer 3-speed hubs feel and shift much better than the originals. I was able to run the shifter cables using the original bosses and did away with the plastic cover that comes with the new hubs:<br />
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<a href="http://1.bp.blogspot.com/-W-1ORqICJ-w/T5wlz8O-CBI/AAAAAAAAD1I/3soRwxVEH_U/s1600/_DSC0572.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="424" src="http://1.bp.blogspot.com/-W-1ORqICJ-w/T5wlz8O-CBI/AAAAAAAAD1I/3soRwxVEH_U/s640/_DSC0572.JPG" width="640" /></a></div>
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The last thing to do was set up the lights. After developing a <a href="http://minisystem.blogspot.com/2011/12/flashing-dynamo-light-prototype.html">standlight circuit</a>, I had to figure out how to <a href="http://minisystem.blogspot.com/2012/01/sturmey-archer-headlight-cree-xm-l.html">mount a LED on a heat sink</a> and <a href="http://minisystem.blogspot.com/2012/04/sturmey-archer-light-set-led-upgrade.html">fit it all in the housing</a> of an<a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-lamps-second-attempt.html"> original Sturmey Archer headlamp</a> and <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">develop a LED bulb</a> for the taillight. I discovered that the original Raleigh lamp bracket didn't work with the SR stem, so had a new <a href="http://minisystem.blogspot.com/2012/04/raleigh-style-headset-mounted-lamp.html">longer bracket fabricated</a> and chromed:<br />
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<a href="http://4.bp.blogspot.com/-G5ZzA9VK12o/T5w3hYCPdMI/AAAAAAAAD4E/K8qWGjAcXEs/s1600/IMG_20120426_182409.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://4.bp.blogspot.com/-G5ZzA9VK12o/T5w3hYCPdMI/AAAAAAAAD4E/K8qWGjAcXEs/s640/IMG_20120426_182409.jpg" width="640" /></a></div>
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I spent an evening mounting the lights and wiring them up. The matching taillight for the Sturmey Archer headlight was <a href="http://minisystem.ca/light_thief.html">stolen</a>, so I had to settle for a vintage <a href="https://www.google.ca/search?q=luxor+taillight&hl=en&prmd=imvns&source=lnms&tbm=isch&ei=aDycT8a2IIrqgge698GeAQ&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CCUQ_AUoAQ&biw=1796&bih=937">Luxor taillight</a>, which polished up to a near chrome-like finish. It's a surprisingly good looking match considering the Luxor is meant for a different <a href="http://www.flickr.com/photos/cycleczar/sets/72157623044309220/">era and style of cycling</a>. In anticipation of using an original Sturmey Archer taillight, I made a <a href="http://minisystem.blogspot.ca/2011/12/upgrading-wedge-base-bulb-in-sturmey.html">wedge-based LED bulb</a>, complete with copper heat sink. However, I decided to save that set for another project. The Luxor uses a threaded bulb, so I just made up an <a href="http://minisystem.blogspot.ca/2011/12/copper-based-led-bulb-fitting-and.html">E10 copper-topped LED bulb</a> with a red<a href="http://www.cree.com/products/pdf/xlampxp-e.pdf"> Cree XP-E</a>. The XP-E, driven at ~500mA from the dynamo, is extremely bright, easily rivalling the current batch of boutique super bright battery taillights.<br />
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<tr><td><a href="http://1.bp.blogspot.com/--dnqehS-J3k/T5wnjbgtQYI/AAAAAAAAD3I/urJUNmmwU_I/s1600/_DSC0617.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="424" src="http://1.bp.blogspot.com/--dnqehS-J3k/T5wnjbgtQYI/AAAAAAAAD3I/urJUNmmwU_I/s640/_DSC0617.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">Luxor tailight takes an <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">LED E10 threaded bulb</a><br />
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Here are a few more photos. The <a href="http://www.flickr.com/photos/bicilux/sets/72157629920083389/with/7122265949/">complete set is on Flickr</a>.<br />
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Now it's just a matter of putting some miles on the bike (ideally at night!) to see what comes loose and to work out any gremlins in the lighting system. Inevitably, there will be some...minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com2tag:blogger.com,1999:blog-3561798115215934165.post-4703605385109972982012-04-20T12:40:00.000-04:002012-04-20T12:40:44.494-04:00Sturmey Archer light set LED upgrade with standlightIt's been a long time in the making, but I've finally finished retrofitting the Sturmey Archer head/taillight set for my wife's bike with power LEDs and a standlight. It all started back in 2008 with my efforts to upgrade a GH6 Dynohub powered lighting system with <a href="http://minisystem.blogspot.ca/2008/07/dynamo-lithium-ion-battery-charging.html">LEDs and lithium ion powered standlight</a> on a dilapidated old Superbe. Sadly, some <a href="http://minisystem.ca/light_thief.html">jerk stole the taillight</a>. The system didn't perform well anyway, which led me to explore ways of <a href="http://minisystem.blogspot.ca/2011/09/charging-supercapacitors.html">charging supercapacitors</a> to power standlights. After acquiring another <a href="http://minisystem.blogspot.ca/2011/11/sturmey-archer-lamps-second-attempt.html">NOS set of Sturmey Archer lamps</a>, I set to work on an updated retrofit.<br />
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I had originally <a href="http://minisystem.blogspot.ca/2011/12/flashing-dynamo-light-prototype.html">designed the circuit</a> so a switch could select between flashing and solid modes, but it turned out that the Zener diode that needs to shunt the dynamo current during the off-cycle of the flash wasn't up to the task. I'm quite convinced of the <a href="http://minisystem.blogspot.ca/2011/09/tail-lamps-to-flash-or-not-to-flash.html">value of flashing lights</a> in urban settings, but in this case I've settled for solid lights while moving and a flashing standlight. The circuit has had a reasonable amount of bench testing on my <a href="http://minisystem.blogspot.ca/2011/11/sturmey-archer-lamps-second-attempt.html">dynamo testing jig</a>, but it's now time to bundle it all into the lamp housing, put it on the bike and start riding with it. Here are a few pictures of the board with switch and copper heat sink mounted LED (described <a href="http://minisystem.blogspot.ca/2012/01/sturmey-archer-headlight-cree-xm-l.html">elsewhere</a>):<br />
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The orignal selector switch on the top of the housing proved unreliable, so I enlarged an existing hole in the bottom of the housing to hold the switch, which has a nice rubber boot. Mounting the PCB was a little fiddly. A tiny L-bracket with one #4-40 tapped hole is used to mount the circuit board to the lamp housing:<br />
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The board looks like an odd fit, but that's because I made it as small as I possibly could, with the hope of fitting into smaller vintage lamp housings, such as the <a href="http://minisystem.blogspot.ca/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">Luxor 65</a>.<br />
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It all fits together nicely, with the retrofitted LED/heat sink/optics and switch looking fairly inconspicuous:<br />
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The <a href="http://minisystem.blogspot.ca/2011/12/upgrading-wedge-base-bulb-in-sturmey.html">taillight LED </a>is ready to go, although I need to get the brown plastic taillight chromed (a gift from a generous reader!). I intend to save my really nice NOS SA lampset for some other project. Once the taillight is chromed (technically, <a href="http://www.vacuummetallizing.ca/">vacuum metallized</a>), I just need to hook up the taillight and dynamo wires and mount the lamps on the bike.<br />
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Future improvements could include a taillight flashing system, where the headlight is never disconnected from the dynamo, alleviating the problem of surging dynamo voltage when flashing both LEDs. I implemented this on a breadboard using a low-side N-FET to short the taillight LED, under the control of an <a href="http://minisystem.blogspot.ca/2012/01/programming-attiny10-with-avrisp-mkii.html">Attiny10</a>. This also has the advantage of smaller and fewer components than a 555-based flasher.<br />
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Another improvement I'd like to eventually make is to <a href="http://minisystem.blogspot.ca/2012/02/ledil-optic-improves-sturmey-archer.html">upgrade the optics</a>. The headlight uses a Cree XM-L, which can take up to 3A of current. Unfortunately, small format narrow beam optics aren't yet available for the XM-L, but they are for its cousin the XP-G, whose 1A current maximum can easily handle the dynamo's output. The XM-L optic certainly improves the beam shape, but it still doesn't have as much throw as I would like. The best solution would be to fabricate a new heat sink for the XP-G and uses a <a href="http://www.ledil.com/node/2/p/1547">narrower optic</a>.minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com7tag:blogger.com,1999:blog-3561798115215934165.post-26599843992441469412012-04-12T00:14:00.000-04:002012-04-12T11:30:14.980-04:00Raleigh-style headset mounted lamp bracket<span style="font-family: inherit;">While I patiently wait for the <a href="http://bicilux.com/">Bici Lux</a> <a href="http://minisystem.blogspot.ca/2012/02/new-bicycle-headlamp-design-philosophy.html">Nº58A</a> prototype to arrive from Australia, I've had some time to work on my wife's 'new' Raleigh Sprite Mixte. Her </span><span style="font-family: inherit;">1966 Superbe was heavy and very beaten up, so I decided to replace it with my Mom's mid 1980s Raleigh Sprite, which had been languishing in the garage for the better part of two decades. It cleaned up beautifully and the paint on the frame and fenders still looks great, with only a few scuffs and scrapes and no rust. I upgraded it with a new wheelset, including a Sanyo H27 hub dynamo from the nice gentleman at </span><a href="http://www.longleafbicycles.com/" style="font-family: inherit;">Long Leaf Bicycles</a><span style="font-family: inherit;">. Despite the restoration being more of an upgrade to modern parts, I wanted to use an original </span><a href="http://minisystem.blogspot.ca/2011/11/sturmey-archer-lamps-second-attempt.html" style="font-family: inherit;">Sturmey Archer lamp set</a><span style="font-family: inherit;"> (upgraded with modern LEDs, of course, both </span><a href="http://minisystem.blogspot.ca/2012/01/sturmey-archer-headlight-cree-xm-l.html" style="font-family: inherit;">front</a><span style="font-family: inherit;"> and </span><a href="http://minisystem.blogspot.ca/2011/12/upgrading-wedge-base-bulb-in-sturmey.html" style="font-family: inherit;">rear</a><span style="font-family: inherit;">, and a </span><a href="http://minisystem.blogspot.ca/2011/12/flashing-dynamo-light-prototype.html" style="font-family: inherit;">standlight</a><span style="font-family: inherit;">). My wife's old Raleigh Superbe had one of the nice Heron-style headset mounted lamp brackets. These are plentiful and can still be purchased as </span><a href="http://www.bikeville.com/accessories.html" style="font-family: inherit;">NOS</a><span style="font-family: inherit;">:</span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img border="0" height="320" src="http://images.andale.com/f2/115/106/3561856/1107600710408_misc_raleigh_light_bracket.jpg" style="margin-left: auto; margin-right: auto;" width="193" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Original Raleigh Heron bracket</td></tr>
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<span style="font-family: inherit;"><br /></span><br />
<span style="font-family: inherit;">A few weeks ago I finally got around to mounting the lamp set and started by popping off the stem, placing the bracket in the headset stack and slipping the lamp's bracket over the Heron mount. But, lo and </span>behold<span style="font-family: inherit;">, the bracket was too short, resulting in the butt of the lamp jammed up too close to the stem's handlebar mount. Turns out, the later model Sprite's used the modern forged aluminium quill stem, which is shorter and stubbier than the older chrome plated stems. The stubbier geometry was the problem and the original Heron bracket simply wasn't long enough.</span><br />
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<span style="font-family: inherit;">Since the bike itself was free (thanks Mom!), I decided it would be worth investing a bit in getting the perfect lamp mounting solution. To accomodate the 700c wheel size, I'd already had a custom drop bolt for the rear brake machined anyway, so why not go to the trouble of custom fabricating another part? If that's not true love, I don't know what is. </span><br />
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<span style="font-family: inherit;">I've been busy designing a sheet metal bracket for my <a href="http://minisystem.blogspot.ca/2012/02/new-bicycle-headlamp-design-philosophy.html">headlamp prototype</a>, so I thought I'd have a go at making a longer Raleigh-style headset mounted lamp bracket. My limited manufacturing experience has been restricted to CNC machining, so sheet metal design was new to me. Essentially, you design a flat part and then modify it by bending. If, like me, you're using cheapy <a href="http://www.punchcad.com/p-8-viacad-pro-v7.aspx">prosumer CAD software</a>, then the fabricator needs to 'unfold' your part to get a flat 2D profile again, which now accounts for the deformation caused by bending. This unfolded profile is laser cut and then bent on a press brake. Here's what I came up with:</span><br />
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<span style="font-family: inherit;">First, the 2D profile:</span><br />
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<a href="http://3.bp.blogspot.com/-6xglNEsrYMw/T4X5zew9mzI/AAAAAAAADrc/qNYYCgp6Luc/s1600/RHB01B+flat.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://3.bp.blogspot.com/-6xglNEsrYMw/T4X5zew9mzI/AAAAAAAADrc/qNYYCgp6Luc/s640/RHB01B+flat.png" width="260" /></a></div>
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<span style="font-family: inherit;">and after bending and rendering:</span><br />
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<a href="http://1.bp.blogspot.com/--gc46ru4wDU/T4WrO8HsB3I/AAAAAAAADq8/L1V_oraLqYk/s1600/RHB01B.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="456" src="http://1.bp.blogspot.com/--gc46ru4wDU/T4WrO8HsB3I/AAAAAAAADq8/L1V_oraLqYk/s640/RHB01B.jpg" width="640" /></a></div>
<span style="font-family: inherit;">The lightening bolt is, perhaps, an </span>unnecessary<span style="font-family: inherit;"> frill, but I was inspired by the old <a href="http://homepage3.nifty.com/ClassicBicycles/brands/jos.html">JOS logo</a> and couldn't resist. For fabrication, I used a <a href="http://questadesign.com/">nice place</a> in Scarborough that was one of the few places that was happy to do a single piece for a reasonable price (in this case, I got two as they were unhappy with the forming marks on the first one they fabricated). Half of the places I emailed never got back to me, so kudos to <a href="http://questadesign.com/">Questa Design</a> for working with the little guy. Here's the custom bracket compared to the original Raleigh Heron bracket:</span><br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-TsFzZ4fWFjE/T4ZRP3v5YyI/AAAAAAAADsM/6jYClk8HwhA/s1600/IMG_5378.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-TsFzZ4fWFjE/T4ZRP3v5YyI/AAAAAAAADsM/6jYClk8HwhA/s640/IMG_5378.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Custom long bracket and Raleigh Heron headset mounted lamp brackets</td></tr>
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<span style="font-family: inherit;">Here it is mounted on the headset:</span><br />
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<a href="http://4.bp.blogspot.com/-2PsdAxTPmV0/T4ZQ-I2hTKI/AAAAAAAADsE/TkFTPz2sLvc/s1600/IMG_5387.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://4.bp.blogspot.com/-2PsdAxTPmV0/T4ZQ-I2hTKI/AAAAAAAADsE/TkFTPz2sLvc/s640/IMG_5387.JPG" width="640" /></a></div>
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<span style="font-family: inherit;">And with a vintage Sturmey Archer headlamp:</span><br />
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<a href="http://2.bp.blogspot.com/-IbzO40hzges/T4ZQvA4h3xI/AAAAAAAADrw/lihAPbnqz2k/s1600/IMG_5384.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://2.bp.blogspot.com/-IbzO40hzges/T4ZQvA4h3xI/AAAAAAAADrw/lihAPbnqz2k/s640/IMG_5384.JPG" width="640" /></a></div>
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<span style="font-family: inherit;">All seems well, although I need to get it <a href="http://metalcoaters.ca/">chromed</a> first before I finalize the installation. The only thing I'm a little worried about is how easily it will get knocked out of alignment. The orignal bracket had a <a href="http://en.wikipedia.org/wiki/Keyway_(engineering)">keyway</a> that interfaced with a groove in the fork thread to prevent rotation. The Sprite's fork thread has no such groove, so the only thing preventing rotation is the headset nut. Hopefully a bit of Loctite or maybe even a rubber washer will prevent unwanted rotation of the bracket.</span>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com2tag:blogger.com,1999:blog-3561798115215934165.post-70610178340962520142012-02-17T00:57:00.000-05:002012-02-17T11:14:04.021-05:00A new bicycle headlamp design: philosophy and rationaleIn my opinion, contemporary bicycle light offerings have not kept pace with the demand for classically inspired bicycle components. Companies like <a href="http://veloorange.com/">Velo Orange</a>, <a href="http://www.rivbike.com/Default.asp">Rivendell</a> and now <a href="http://www.compasscycle.com/Home.html">Compass Bicycles</a> have fed demand for newly manufactured retro-styled components to update vintage frames as well as to equip the growing number of available lugged steel frames inspired by classic touring, randonneuring and racing bicycles. These 'modern classical' builds can now be built with new handlebars, brakes, levers, rims, cranksets, saddles, stems, racks and fenders, all conforming to the new retro aesthetic defined mostly by Velo Orange and Rivendell.<br />
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However, contemporary headlight offerings that match a modern classical build are limited. The best, and most popular option is the <a href="http://www.peterwhitecycles.com/edelux-info_PWC08-02-4.pdf">Edelux</a> by <a href="http://www.nabendynamo.de/english/index.html">Schmidt</a>. I have one on my 1970s Holdsworth Super Mistral and it is a great looking and performing light. Its polished aluminum finish certainly agrees with the modern classicist's backlash against anodizing of any kind (here, the other major boutique player, <a href="http://www.supernova-lights.com/en/index.html">Supernova</a>, falls short). The light is diminutive (85g!) and the hemispherical design is certainly better than anything else out there, vaguely reminiscent of the <a href="http://homepage3.nifty.com/ClassicBicycles/brands/soubitezgolfballsw.html">Soubitez 'golf ball'</a>. Still, in my opinion, it looks a bit out of place on a vintage or modern classical build. <br />
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Other contemporary offerings in the vintage vein include the Lumotec <a href="http://www.bumm.de/produkte/dynamo-scheinwerfer/lumotec-retro.html">Retro</a> and the recently introduced <a href="http://www.bumm.de/produkte/dynamo-scheinwerfer/lumotec-classic.html">Classic</a> from Busch & Müller. The Classic is chromed and has a nice retro-looking selector switch, but on the whole I think it's one ugly duck. The Retro is a little better looking than its younger sibling. I used to have one and it is just a Lumotec halogen lamp with a chromed plastic shell to retro-fy it.<br />
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After that your options are limited to a <a href="http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dsporting&field-keywords=chrome+bullet+bike+light">handful of cheap chromed bullet lamps</a> from Taiwan or you can hunt down a vintage French headlamp, something I used to do with more enthusiasm before increased demand drove up Ebay prices.<br />
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I'm <a href="http://minisystem.blogspot.com/2011/11/specific-aim-1-making-led-light-bulb.html">forever</a> <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">experimenting</a> with upgrading <a href="http://minisystem.blogspot.com/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">vintage bike lights</a> with modern <a href="http://minisystem.blogspot.com/2011/09/choosing-leds-and-batchpcb-success.html">LEDs</a> and <a href="http://minisystem.blogspot.com/2012/02/incandescent-optics-versus-led-optics.html">optics</a>, but these efforts have led to me to conclude that the best option for a modern build would be a completely new lamp designed from scratch. Something bright, elegant and weatherproof.<br />
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So, I designed one, hereby christened the <span style="background-color: white; line-height: 20px;"><span style="font-family: Times, 'Times New Roman', serif;">Nº</span></span><span style="font-family: Times, 'Times New Roman', serif;">58A. </span><br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-QwkyipjK3n4/Tz1AQnQJh6I/AAAAAAAADS4/InRSQTVMXx0/s1600/bicilux_banner_small.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="314" src="http://1.bp.blogspot.com/-QwkyipjK3n4/Tz1AQnQJh6I/AAAAAAAADS4/InRSQTVMXx0/s320/bicilux_banner_small.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Nº58A headlamp</td></tr>
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This design references the elegant teardrop shape of the classic French lamp makers like Radios, Luxor, Soubitez and JOS, which were made of spun aluminum. The lamp housing, bezel and bracket will be CNC machined and, of course, it will have a modern LED with standlight. <br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-iApTrlfF6SU/Tz1LUES-5PI/AAAAAAAADTs/m5U-kBWKPaA/s1600/No58Axsection.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="408" src="http://3.bp.blogspot.com/-iApTrlfF6SU/Tz1LUES-5PI/AAAAAAAADTs/m5U-kBWKPaA/s640/No58Axsection.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Nº58A cross section</td></tr>
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Good <a href="http://minisystem.blogspot.com/2011/12/hot-led-lux-readings-of-cree-xp-g-on.html">thermal management</a> is crucial to <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">LED performance</a>, so the LED is mounted on a large copper heat sink that transmits heat away from the LED through the lamp housing. My design is for a dynamo powered lamp to begin with but the Cree XM-L can be driven up to 3A, so a battery powered version (with an external battery pack, unfortunately) is an option down the road. The heat sink is very likely up to the task. The reflector is, out of necessity, an off-the-shelf model designed for use with Cree XP LEDs. The beam is tightly focused but with enough spill to provide good off axis visibility in traffic. I haven't done a detailed analysis of the beam shape but it reminds me of my Supernova's beam: round and symmetrical. A reflector that produces an asymmetrical cutoff beam like that of the popular <a href="http://swhs.home.xs4all.nl/fiets/tests/verlichting/koplampen/BM_IQ_reflector/index_en.html">B&M IQ reflector</a> is not available in the format I need.<br />
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-s70pXuqOROQ/Tz19JnDf_KI/AAAAAAAADUE/afh-A0nzPyE/s1600/BICILUX+No58A.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="334" src="http://2.bp.blogspot.com/-s70pXuqOROQ/Tz19JnDf_KI/AAAAAAAADUE/afh-A0nzPyE/s640/BICILUX+No58A.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Nº58A dimensions</td></tr>
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The headlight is on the larger size, about 58mm (2.3in) at its largest diameter and 77mm (3in) long, though still smaller than classic French teardrop lamps such as the Radios Nº18 and the Luxor 65. It's also quite hefty; based on volume and material density calculations, around 228g or 8oz. Almost certainly too heavy for fender mounting (at least without a second set of stays), but fine for mounting on a front rack or fork crown. The weight is due to a combination of thicker walls than traditional spun aluminium and the dense copper heat sink. One advantage of the thicker CNC fabrication is that it shouldn't dent like old spun housings. <br />
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A friend of mine kindly put together a few photorealistic views in polished aluminium:<br />
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You can see the complete set here on <a href="http://www.flickr.com/photos/bicilux">Flickr</a>.<br />
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Noticeably absent from my drawings is a switch. Finding a place for a power switch has been the most challenging design issue. Vintage French lamps were almost universally bottle dynamo powered, precluding the need for a switch. There isn't a compact enough selector switch available to mimic the switch of the old Sturmey Archer headlights. I contemplated something similar to the clever magnetic reed switch used on the Edelux, but that design requires custom plastic parts. In the end, I decided to go for a short actuator toggle switch with a splash proof boot. You can see its placement in the following renderings:<br />
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<a href="http://1.bp.blogspot.com/-WqUvOtIR624/Tz1AhA4Jd-I/AAAAAAAADTU/qdTmylNAZNU/s1600/Lamp+solid+view+1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="390" src="http://1.bp.blogspot.com/-WqUvOtIR624/Tz1AhA4Jd-I/AAAAAAAADTU/qdTmylNAZNU/s400/Lamp+solid+view+1.jpg" width="400" /></a></div>
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Shown is a switch with a flatted actuator, but I'll probably use a standard round actuator as it fits better in the boot and creates a better seal. The seam between the lamp housing and bezel will be sealed with silicone grease and an o-ring will seal between the bezel and glass lens.<br />
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At the moment, I'm finalizing a quote with a prototype maker. With a prototype in hand I'll be able to spend the spring and summer riding with it, running it in the shower, hitting it with a hammer, striking it with lightning, etc, etc. Then, if there's enough demand, I might consider doing a small production run. I'll post updates about the project here. If you're interested, please comment below or send me an email (address at bottom of page). I've even reserved a name for this putative enterprise: <a href="http://bicilux.com/">Bici Lux</a>.<br />
<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com10tag:blogger.com,1999:blog-3561798115215934165.post-38972277370131096632012-02-10T22:53:00.000-05:002012-02-10T22:53:18.803-05:00Free CAD software: 3D, 2D, and PCB layoutI rely heavily on CAD freeware for all my weird obsessive bike light projects. Never having been a professional engineer or designer, I haven't had the luxury of being able to snag a copy of any commercial CAD software from my workplace. Licenses for such things run into the thousands of dollars (I emailed <a href="http://www.solidworks.com/">Solidworks </a>a few months ago to get a quote for an individual license for hobby use and they asked for a cool $2000). No thank you!<br />
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It took me a long time to discover the tools that I use to design parts in 3D, draft them in 2D, capture schematics and layout PCBs. Here's a list of the free CAD software I find most useful:</div>
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<b><span style="color: #999999; font-family: Arial, Helvetica, sans-serif; font-size: x-large;">3D CAD</span></b></div>
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<a href="http://www.emachineshop.com/"><span style="font-family: Arial, Helvetica, sans-serif;">eMachineShop</span></a></div>
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Man, I really like this software. If you're a CAD veteran you might hate it but for the beginner I don't think it could get any easier than this. The software is specifically for designing single machine parts and the design restrictions do a good a job of preventing you from designing something that can't be machined. Living within the software's rules can be a frustrating limitation at times and I'm often forced to think outside the box (so to speak) to design a specific feature on a part (cutting a feature out of a solid, for example, uses a kind of confusing 'air inside/outside' paradigm). It kind of forces you to think like a CNC machine, which is no bad thing if you want your part design to actually be machinable. Making parts by revolving a profile is very straightforward. The autosnapping is fantastic - no key combinations are required to snap to midpoints, endpoints, centers, tangents, etc. Best snapping interface I've encountered, allowing me to work fast. However, complicated parts with many surface features on different axes are not this application's forte. If I need to do more complicated Boolean shaping then I modify my part in FreeCAD.</div>
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eMachineShop wants you to use their machining service and there's a handy online quote generator that allows you to get pricing for different materials and tolerances. For pieces out of steel and aluminium, I find their prices competitive with other big online CNC services like <a href="http://www.quickcutcnc.com/">QuickCut </a>and <a href="http://www.firstcut.com/">Firstcut</a>. All three online machine services quote about 1.5-10 times higher for the same material than most of the prototype makers I've contacted in China. I've used eMachineShop's fabrication service once and was disappointed with the quality of the material and the use of an inferior machining method (plus they initially over charged me for shipping - $128 UPS to Canada!). The part was within tolerances and performed its function, but eMachineShop's off my list of prototype makers for now. Most folks report a good experience, so I'm aware that my dissatisfaction was an exception.</div>
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To their credit, eMachineShop's CAD software allows you to export 3D IGES files as well as 2D DXF files. The 3D export has a disclaimer that it's still a work in progress, but for the most part the original design survives the export. For some reason, adding holes to curved surfaces starts to screw things up, a problem that can be solved by modifying the part in FreeCAD.<br />
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Although I haven't used it, eMachineShop does support CNC bending, so you can design parts bent out of sheet metal. Unfortunately, the bends are not exported in the 3D IGES file, so you wind up with a flat version of your part on export. I'm not sure if the .igs file plus a 2D description of the bend locations, their radii and angles would be enough to get a quote from a third party fabricator.</div>
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<a href="https://sourceforge.net/apps/mediawiki/free-cad/index.php?title=Main_Page"><span style="font-family: Arial, Helvetica, sans-serif;">FreeCAD</span></a></div>
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I love it and hate it. It's deep but challenging. For <i>de novo</i> part design of anything but the most basic fundamental shapes, I stick with eMachineShop and then modify the part in FreeCAD. For the most part, I use FreeCAD to make part assemblies so I can see how everything fits together. The Boolean operations are good for cutting one complicated shape from another, something that I can't do in eMachineShop. FreeCAD is still under heavy development, which means it can be a bit buggy and frustrating to use sometimes. It has a small <a href="https://sourceforge.net/apps/phpbb/free-cad/">community of enthusiasts</a> where you can get help. The forum is particularly valuable for finding scripts to make complicated features that would be difficult or impossible to do with just the GUI. A <a href="https://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=3&t=2154">helical thread</a>, for instance. FreeCAD looks and feels very promising, but the frequently buggy Boolean operations and a lack of complete GUI implementation of all features is holding it back from a wider audience of prospective users. For my purposes, though, it is perfectly adequate.</div>
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One feature I've discovered recently is the <a href="http://sourceforge.net/apps/mediawiki/free-cad/index.php?title=Drawing_Module">Drawing Module</a>, which lets you generate 2D drawings of your part, including isometric views. The GUI implementation is almost nil, so you spend a lot of time manipulating objects by command line, but the results are pretty cool:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-uiKKzcsF-74/TzVhYgZsHFI/AAAAAAAADPw/HBDmfwz2-dA/s1600/FreeCAD+lamp+shaded.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="328" src="http://4.bp.blogspot.com/-uiKKzcsF-74/TzVhYgZsHFI/AAAAAAAADPw/HBDmfwz2-dA/s400/FreeCAD+lamp+shaded.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Taillight concept 3D</td></tr>
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-yrcwvPWy7Tk/TzVhYp7lqAI/AAAAAAAADP0/MEVpp4pRNvE/s1600/FreeCAD+lamp+drawing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="283" src="http://2.bp.blogspot.com/-yrcwvPWy7Tk/TzVhYp7lqAI/AAAAAAAADP0/MEVpp4pRNvE/s400/FreeCAD+lamp+drawing.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Taillight 2D isometric view</td></tr>
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The results of the isometric projection can be cleaned up with DraftSight.<br />
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<a href="http://igsviewer.com/IGS-file-viewer/Brand%20new.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="111" src="http://igsviewer.com/IGS-file-viewer/Brand%20new.gif" width="100" /></a></div>
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<a href="http://igsviewer.com/"><span style="font-family: Arial, Helvetica, sans-serif;">IGSViewer</span></a></div>
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Prototyping services seem to like IGES format for quotations, so I use IGSViewer to check the outputs of both eMachineShop and FreeCAD to make sure nothing wonky has happened during export.<br />
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<b><span style="color: #999999; font-family: Arial, Helvetica, sans-serif; font-size: x-large;">2D CAD</span></b></div>
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<a href="http://www.solidworks.com/pages/programs/letsgodesign/images/downloads/DraftSightFiles.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="94" src="http://www.solidworks.com/pages/programs/letsgodesign/images/downloads/DraftSightFiles.jpg" width="100" /></a></div>
<span style="font-family: Arial, Helvetica, sans-serif;"><a href="http://www.3ds.com/products/draftsight/overview/">DraftSight</a></span></div>
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A new piece of software for 2D drafting, it is quite deep with a reasonably good interface. Like eMachineShop, the implementation of snapping to endpoints, midpoints, tangents, perpendicular, etc. is very handy, although you need to turn it off if you don't want to snap to the nearest feature, no matter how far away it seems. I usually import the DXF output from eMachineShop into DraftSight where I can build up my 2D drafts. The isometric views that FreeCAD spits out in .svg format can be imported (via InkScape) and cleaned up to produce pretty nice looking technical drawings. Dimensioning is pretty straightforward, although I often wind up fighting with the global attribute system. For freeware this is very well-developed. Not sure the story behind it. Perhaps it's just intended as a halo application for its super expensive big brother, Solidworks.<br />
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<a href="http://icons.iconarchive.com/icons/oxygen-icons.org/oxygen/256/Apps-inkscape-icon.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="100" src="http://icons.iconarchive.com/icons/oxygen-icons.org/oxygen/256/Apps-inkscape-icon.png" width="100" /></a></div>
<a href="http://inkscape.org/"><span style="font-family: Arial, Helvetica, sans-serif;">InkScape</span></a><br />
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Big freeware competitor to Illustrator. I've only used it to convert .svg to .dxf for FreeCAD drawing import into DraftSight, but it looks pretty cool. I've never been an Illustrator user, so I don't imagine using his much, but it sure is handy for the very specific file conversion I need to do.<br />
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<b><span style="background-color: white; color: #999999; font-family: Arial, Helvetica, sans-serif; font-size: x-large;">PCB CAD</span></b><br />
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<a href="http://sensi.org/~svo/eagle/icon_cadsoft_eagle.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="100" src="http://sensi.org/~svo/eagle/icon_cadsoft_eagle.png" width="100" /></a></div>
<span style="font-family: Arial, Helvetica, sans-serif;"><a href="http://www.cadsoftusa.com/downloads/freeware/">Eagle CAD</a></span><br />
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This software is an electronic hobbyist's dream come true. I found the learning curve a bit steep, but once you get it Eagle CAD becomes a great all-in-one schematic capture and PCB layout application. There is a good <a href="http://www.sparkfun.com/tutorials/109">tutorial</a> from Sparkfun to get you started. The large libraries of components never seem to have the specific parts I want to use, so I've had to get used to designing my own schematic symbols, laying out the pads according to the datasheet's description of the device's footprint and adding the part to my own custom library. This is kind of a pain in the butt, but I guess you can't expect the libraries to be completely exhaustive. The freeware version has a limited board size (plenty of space for what I want to do) and only supports 2 layer designs (the PCB house I use only offers 2 layer fabrication). The autorouter seems to do a good job of routing the connections after placing the parts. I typically don't route manually, instead shifting parts around until the autorouter hits 100%. In the world of PCB design, that makes me a bit of a loser. So be it.</div>
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I'm sure I'm missing out on other great CAD tools. Let me know what your essential pieces of free CAD software are.</div>
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<br /></div>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com1tag:blogger.com,1999:blog-3561798115215934165.post-59031489548722439992012-02-06T21:19:00.000-05:002012-02-06T21:19:06.637-05:00Classic bicycle taillights<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-w8YcafEBanI/Ty_ehySE6wI/AAAAAAAADO8/gu3itzUEHqk/s1600/3358073180_ff9ff88d29_b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-w8YcafEBanI/Ty_ehySE6wI/AAAAAAAADO8/gu3itzUEHqk/s640/3358073180_ff9ff88d29_b.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Luxor Le Martelé taillight. Photo by <a href="http://www.flickr.com/photos/36397392@N06/">J Ferguson</a></td></tr>
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I love classically styled bicycle taillights, especially those of the French persuasion. I have a handful of <a href="http://www.google.ca/search?q=luxor+tail+light&hl=en&site=webhp&prmd=imvns&source=lnms&tbm=isch&ei=IN8vT8HaDoWW0QGP75HICg">Luxor tail lamps</a> waiting for the right project to come along (yes, I'm the type that would build a bike around a taillight). I just discovered this <a href="http://www.flickr.com/photos/aalpern/galleries/72157622502919702/">gallery on Flickr</a> dedicated to curating photos of both vintage and handmade taillights. As well, there's this <a href="http://homepage3.nifty.com/ClassicBicycles/brands/brands.html">great Japanese site</a> that has examples of classic lights from <a href="http://homepage3.nifty.com/ClassicBicycles/brands/radios.html">Radios</a>, <a href="http://homepage3.nifty.com/ClassicBicycles/brands/luxor.html">Luxor</a>, <a href="http://homepage3.nifty.com/ClassicBicycles/brands/soubitez.html">Soubitez </a>and <a href="http://homepage3.nifty.com/ClassicBicycles/brands/jos.html">JOS</a>.<br />
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Unfortunately, modern taillights are invariably plastic and utilitarian in nature. <a href="http://www.compasscycle.com/Home.html">Compass Bicycles</a> had a <a href="http://janheine.wordpress.com/2011/12/09/new-led-taillight-solutions/">recent post</a> bemoaning the indifference to elegance in contemporary taillight offerings. If you want a nicely designed light suitable for your modern classical build, you're looking at acquiring something vintage (these options from <a href="http://www.jitensha.com/eng/kimura_lights.html">Kimura </a>notwithstanding). If you're into classic randonneuring bikes, then vintage options can get very expensive.<br />
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Although I'm partial to the fender-mounted teardrop-shaped Luxor lights, I also really like the<a href="http://www.blackbirdsf.org/jos/tail.html"> JOS tail lamps</a>, especially the <a href="http://www.blackbirdsf.org/jos/typefu.html">Fu model</a>. Here is a beautiful example from Flickr:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-obUOaccyjC4/TzASAy5m78I/AAAAAAAADPY/0-vYuwWzrMQ/s1600/JOSFu.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto; text-align: center;"><span style="font-size: x-small;"><img border="0" height="422" src="http://3.bp.blogspot.com/-obUOaccyjC4/TzASAy5m78I/AAAAAAAADPY/0-vYuwWzrMQ/s400/JOSFu.jpg" width="430" /></span></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">JOS Fu taillight. Photo by s<a href="http://www.flickr.com/photos/10703870@N06/">poke sniffer</a>.</td></tr>
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It occurred to me that the symmetrical design would lend itself well to CNC machining. For fun I drafted up a concept:<br />
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<a href="http://2.bp.blogspot.com/-VVMQ7NUe78k/TzAR89rgeKI/AAAAAAAADPQ/D85qI5HREh4/s1600/FU44.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="357" src="http://2.bp.blogspot.com/-VVMQ7NUe78k/TzAR89rgeKI/AAAAAAAADPQ/D85qI5HREh4/s400/FU44.png" width="400" /></a></div>
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This would obviously be equipped with an LED, so the protruding bulb holder with it's knurled binding post isn't required, although it might be nice to incorporate it. The bracket might be a bit of a challenge to have made, but the body could be turned on a lathe without much trouble. The lens, on the other hand, would have to be injection molded, which is associated with high setup costs for unrealistically large volumes. Perhaps a 3D printer could produce something that might work. For now, my classically inspired taillight design will have to remain <i>in silico</i>. What do you think? Does the world need a new taillight?minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com6tag:blogger.com,1999:blog-3561798115215934165.post-51163939595625068472012-02-03T00:37:00.001-05:002012-05-19T10:21:26.245-04:00Ledil optic improves Sturmey Archer Cree XM-L upgradeI recently <a href="http://minisystem.blogspot.com/2012/01/sturmey-archer-headlight-cree-xm-l.html">posted</a> about a Cree XM-L upgrade I designed for the vintage Sturmey Archer head lamp (at least the one seen most commonly on North American Raleighs from the 1970s). The light output is high, but the beam shape has some <a href="http://minisystem.blogspot.com/2012/02/incandescent-optics-versus-led-optics.html">significant shortcomings</a>, rather embarrassing ones considering the centre of the beam from the original bulb was still brighter than the LED upgrade. Yikes!<br />
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The wise and wonderful people at <a href="http://www.candlepowerforums.com/vb/showthread.php?332089-Single-LED-Dyno-Light-w-Standlight">CPF</a> suggested I try a small modern optic instead of relying solely on the vintage reflector. The choice of sub 20mm optics for the XM-L is quite limited. The best I could find was this <a href="http://www.ledil.com/node/2/p/1296">16.1mm 37º optic</a> from Ledil (This <a href="http://www.ledil.com/node/2/p/1303">23º optic</a> would probably be better but wasn't stocked by either Mouser or Digikey). It arrived from Mouser today. I had to snip off the mounting posts, but it otherwise fit perfectly over the XM-L's PCB, attached firmly with its own adhesive tape:<br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-uA7XN-J0rEE/T7epBD_3Y6I/AAAAAAAAECY/gi0EglvBu5k/s1600/IMG_5348.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-uA7XN-J0rEE/T7epBD_3Y6I/AAAAAAAAECY/gi0EglvBu5k/s640/IMG_5348.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ledil 16.1mm 37º optic mounted on XM-L</td></tr>
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<a href="http://minisystem.blogspot.com/2012/02/incandescent-optics-versus-led-optics.html">As before</a>, I measured the beam profile at 2.5m from my lux meter's sensor. Here's the data I would show if I was a savvy marketer:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-EYs_Cl_iOGY/TysuwGEz42I/AAAAAAAADOc/TuSxfg2fwGg/s1600/Ledil+lux+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="481" src="http://1.bp.blogspot.com/-EYs_Cl_iOGY/TysuwGEz42I/AAAAAAAADOc/TuSxfg2fwGg/s640/Ledil+lux+data.jpg" width="700" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Beam profile of Cree XM-L with Ledil optic compared to original incandescent bulb</td></tr>
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Well, that looks great. Big fat wide beam compared to the puny and narrow beam of the original bulb. Of course, that doesn't tell the whole story. Here's the same beam profile compared to not only the original but also to a 0.35A incandescent. The profile of the untreated XM-L's beam is also plotted:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-eVmbjYSQ8HY/TysuuKCiwYI/AAAAAAAADOU/KKE7-xbhU3Q/s1600/SA+all+beam+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="486" src="http://1.bp.blogspot.com/-eVmbjYSQ8HY/TysuuKCiwYI/AAAAAAAADOU/KKE7-xbhU3Q/s640/SA+all+beam+data.jpg" width="700" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Beam profiles of Sturmey Archer lamp with different light sources</td></tr>
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While the Ledil optic does a nice job of evening out the profile of the XM-L's beam and doubles its brightness in the center, the peak output is still a lot lower than a simple incandescent upgrade. Granted, an original Dynohub barely puts out 0.35A at high speeds and the front bulb is usually run in parallel with a 0.1A taillight bulb. What you get from the Cree XM-L is a bright wide beam with lots of spill. This results in a nice amount of off axis visibility, which is important to me in the city traffic where I do most of my riding.<br />
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With the Ledil optic I'm willing to declare my Sturmey Archer LED upgrade a success. There's even the possibility of upgrading to the 23º optic if it ever makes its way over to North American shores.minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com3tag:blogger.com,1999:blog-3561798115215934165.post-37219609196704038612012-02-01T00:51:00.000-05:002012-05-19T10:20:54.579-04:00Incandescent optics versus LED optics: implications for upgrading vintage lampsSometimes facts get in the way of a great idea. I've devoted a lot of time to the problem of upgrading vintage lamps to power LEDs. Power LEDs produce a ton of light, but they get hot and require adequate heat sinking to maintain their output and limit the chance of failure. This led me to develop a series of rather elaborate copper heat sinks. I've made a <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">screw base LED bulb</a>, a <a href="http://minisystem.blogspot.com/2011/12/upgrading-wedge-base-bulb-in-sturmey.html">wedge base LED bulb</a>, and custom LED heat sinks to fit the <a href="http://minisystem.blogspot.com/2012/01/sturmey-archer-headlight-cree-xm-l.html">classic Sturmey Archer headlight</a> as well as the <a href="http://minisystem.blogspot.com/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">Luxor 65 series of vintage French lamps</a>, all using Cree XP-G or XM-L power LEDs. I fired them up from both a DC bench top supply and a hub dynamo and I was impressed with the results. For the Sturmey Archer and Luxor headlamps, the outputs were bright, producing huge floody beams. Before I could make claims about the superiority of these upgrades, though, I thought I should take some lux readings and compare the output of the LED upgrades to that of the original incandescent bulbs.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-B6RvpVI8QgA/TyS8TzJfAGI/AAAAAAAADJI/qF4mckpAyFg/s1600/IMG_5327.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-B6RvpVI8QgA/TyS8TzJfAGI/AAAAAAAADJI/qF4mckpAyFg/s640/IMG_5327.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cree XM-L mounted in Sturmey Archer headlight</td></tr>
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Here is some lux data comparing the output of an original 6V bulb at 350 mA (in actual fact, the original bulb was 6V 0.2A with a parallel 0.1A taillight bulb), a 3W halogen bulb (<a href="http://www.reflectalite.com/halogenpage.html">Reflectalite GH106</a>) at 500 mA and the Cree XM-L upgrade at 500 mA (low end modern hub dynamo output) and 700 mA (high end hub dynamo output as well as <a href="http://minisystem.blogspot.com/2011/12/sturmey-archer-dynohub-magnet-upgrade.html">Dynohub magnet upgrade</a>). Lastly, I measured the output of a Cree XP-G mounted in a <a href="http://www.dealextreme.com/p/aluminum-textured-op-reflector-for-cree-mc-e-led-emitters-41-5mm-18mm-17385">41.5mm reflector</a> designed specifically for Cree LEDs. The lux meter's sensor was placed 1M away from the light source and the centre hot spot of the beam was measured. The lux reading recorded represents the brightest spot of the beam.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-x8YSd6pnFqM/TyYeeg6Yn_I/AAAAAAAADKM/sKBeTJHX1Hk/s1600/lux+data+LED+incandescent+SA.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="495" src="http://3.bp.blogspot.com/-x8YSd6pnFqM/TyYeeg6Yn_I/AAAAAAAADKM/sKBeTJHX1Hk/s640/lux+data+LED+incandescent+SA.jpg" width="700" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lux output of Sturmey Archer headlight with different light sources compared to Cree XP-G with specialized reflector</td></tr>
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Well, what the heck? Is ancient technology really winning? Well........... yes, in a nutshell, it is. :(<br />
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Although I haven't photographed the beams, allow me to emphasize how different the incandescent/halogen beam patterns were compared to the LED patterns. The hot spot of the incandescent/halogen beams that yielded the highest lux reading was very concentrated. The slightest change in position of the beam could see the lux reading tumble by half or more; the focused hot spot was very small and the overall beam was quite narrow, certainly less than 45º. In contrast, the LED upgrades mounted in the same reflectors produced a very diffuse hot spot and a very evenly illuminated flood of probably greater than 120º. The LED upgrade is clearly putting out more light, but it isn't focused like the incandescent bulbs.<br />
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To document this quantitively, I placed the sensor of my lux meter on a tripod and focused the center of the beam on it (highest lux reading). I then took readings at finite distances from the centre of the beam while maintaining the same distance from the light source, essentially creating a brightness profile across the beam's diameter. I rather arbitrarily set the distance at 2.5m. <a href="http://www.lumicycle.com/product/237/single-xpg-systems-1500-lumens.htm">Some bike light makers</a> measure performance by lux at 5m. Lux at 1m also seems to be a common standard, however I was limited by the distance between my work bench and my wall, so 2.5m it is, which is fine for a relative measurement. Here I compare the XM-L's beam to the beams of a 6V 0.35A incandescent as well as the 6V 0.2A incandescent that originally equipped the Sturmey Archer lamp.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-2zbbVqA5lcM/TyjP6HQx1HI/AAAAAAAADN8/i27HUJ7TrQY/s1600/beam+pattern+lux+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="483" src="http://4.bp.blogspot.com/-2zbbVqA5lcM/TyjP6HQx1HI/AAAAAAAADN8/i27HUJ7TrQY/s640/beam+pattern+lux+data.jpg" width="700" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Brightness profile of Sturmey Archer headlight beam with three different light sources</td></tr>
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As you can see, both incandescent bulbs produce a narrow symmetrical beam that drops off to zero between 40-50 cm from the center. The 0.35A bulb has a surprisingly bright peak, whereas the original 0.2A bulb is considerably dimmer. The XM-L beam doesn't have much in the way of a center peak, but provides a wide profile of even illumination. Unusually, it seems to have some asymmetrical artifacts, which I confirmed by measuring the beam in a different axis (not shown). My room wasn't big enough to measure the full width of the XM-L's beam. If was able to, I expect the area under the XM-L's profile curve would be a lot larger than the area under both incandescents' curve (ie. greater total light output).<br />
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The 0.35A bulb isn't an especially fair comparison as the original configuration was a 0.2A bulb, however it does indicate that a simple incandescent upgrade can dramatically improve the light output. Although I didn't measure the beam profile, you can bet that the 0.5A halogen bulb would be even brighter!<br />
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The obvious problem with the XM-L's performance is the optics. The vintage optics are optimized for incandescent bulbs. The limited viewing angle of the LED means that, although a lot more light is coming out of the lamp, the optics aren't focusing it into a tight beam. I had originally fretted that the LEDs weren't in the right position relative to the vertex of the reflector's parabola, but changing that position doesn't have much of an effect on beam pattern. The glass globe of an incandescent lamp allows the filament's light to enjoy a greater than 180º viewing angle. It is my suspicion that it is this backward directed light that is collected and focused by the reflector.<br />
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This LED/incandescent performance difference is less pronounced with the <a href="http://minisystem.blogspot.com/2012/01/power-led-upgrade-for-luxor-65-bicycle.html">Luxor 65 reflector</a>. Interestingly, the results indicate that the Sturmey Archer lamp does a considerably better job of focusing incandescent light into a tight beam.<br />
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<tr><td class="tr-caption" style="text-align: center;">Cree XM-L mounted in Luxor 65 head lamp</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Lux output of Luxor 65 head lamp with different light sources</td></tr>
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So, I think the lesson to be learned here is that there are rather strict limitations to what you can accomplish with a LED retrofit of a vintage lamp. You really are at the mercy of the reflector, which does a surprisingly good job of focusing a small amount of incandescent light into a tight beam, but isn't very compatible with the narrower viewing angle of power LEDs. <br />
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It also really emphasizes how deceiving lumen ratings of LEDs can be. I suppose this is why Maglite uses 'Beam Distance' to measure the <a href="http://www.maglite.com/flashlight_performance.asp">performance of their flashlights</a> rather than total light output or lux at a finite distance (1m, 5m, etc). This is the maximum distance at which a light source will produce 0.25 lux, thus taking into account both the total light output and the throw provided by the optics.<br />
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Modifying or replacing the reflectors of vintage lamps isn't especially practical, so I think I've hit a performance wall here. While the LED upgrades don't produce a tight focused beam, their output still produces a bright flood that is certainly adequate for riding around town at night and maybe along a dark bike path at normal speeds. I haven't done a side-by-side comparison yet, but I'm pretty sure the greater total light output from the LED upgrade will result in greater noticeability in traffic. Careening down a long hill on a moonless night on your vintage French randonneuring bike is probably not advisable though...<br />
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The bright side (forgive me) to all of this is that the rear red LEDs are much much brighter than their original incandescent counterparts. I <a href="http://minisystem.blogspot.com/2011/09/tail-lamps-to-flash-or-not-to-flash.html">fret constantly</a> about being visible from behind when I'm riding, so I'm more concerned about having highly optimized lighting for the taillight. The LED upgrade offers a bright standlight and a super visible rear light (with the potential to flash!), which, for my purposes, makes up for the fact that the head lamp beam pattern is less than optimal.<br />
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Still, hope for a better beam shape is not lost. The opening into the reflectors of both the Sturmey Archer and Luxor lamps is less than 20 mm, but there are modern plastic optics with a diameter less than that. It's possible some modern optic made for the XM-L might improve the beam shape. This one from <a href="http://ledil.fi/node/2/p/1296">Ledil</a> looks promising:<br />
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<tr><td style="text-align: center;"><a href="http://ledil.fi/material/Tina3/Tina3-XM/FA11902/Tina3-W.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://ledil.fi/material/Tina3/Tina3-XM/FA11902/Tina3-W.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://ledil.fi/material/Tina3/Tina3-XM/20110518_ah_Tina3-Series_XM-Assy_Datasheet_rev1.pdf">Ledil Cree XM-L 16.1mm optic</a></td></tr>
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Need to order a couple of these and see if they can improve the beam shape.<br />
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<i>Update: optics arrived and the results are <a href="http://minisystem.blogspot.com/2012/02/ledil-optic-improves-sturmey-archer.html">pretty good</a>.</i><br />
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<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com3tag:blogger.com,1999:blog-3561798115215934165.post-28040751602617491742012-01-31T00:33:00.000-05:002012-05-19T10:19:45.372-04:00Power LED upgrade for Luxor 65 bicycle lamps<div class="separator" style="clear: both; text-align: center;">
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-1v0YMIwNkHc/TyXyl-7JF3I/AAAAAAAADJ8/kg4ScyfqBLw/s1600/4931857031_01340d629a_b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="426" src="http://1.bp.blogspot.com/-1v0YMIwNkHc/TyXyl-7JF3I/AAAAAAAADJ8/kg4ScyfqBLw/s640/4931857031_01340d629a_b.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Luxor 'Le Martelé' lamp set. Photo from <a href="http://www.flickr.com/photos/49353569@N00/4931857031/sizes/l/in/photostream/">jp weigle</a>.</td></tr>
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I'm a <a href="http://minisystem.blogspot.com/2011/10/luxor-dynamo-lamps.html">huge fan</a> of the <a href="http://www.google.ca/search?hl=en&biw=1115&bih=750&tbm=isch&sa=1&q=luxor+65">Luxor 65</a> series of bicycle lamps, especially the hammered aluminium 'Le Martelé'. It took me a while, but after a few months on French Ebay I managed to <a href="http://minisystem.blogspot.com/2011/09/back-to-workbench.html">acquire a set</a>. Naturally, I want to upgrade them with modern power LEDs, as I've done with the <a href="http://minisystem.blogspot.com/2012/01/sturmey-archer-headlight-cree-xm-l.html">classic Sturmey Archer lamp set</a>. Both front and rear lamps use a nicely designed lamp holder that snaps into the reflector/lens base with a pair of spring clips:<br />
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<a href="http://4.bp.blogspot.com/-iZS9UUCB0Nw/Tu5Z450-5WI/AAAAAAAAC4c/Es5V9GuzyfE/s1600/IMG_5106.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="http://4.bp.blogspot.com/-iZS9UUCB0Nw/Tu5Z450-5WI/AAAAAAAAC4c/Es5V9GuzyfE/s400/IMG_5106.JPG" width="400" /></a></div>
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For the rear lamp I can use a <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">screw base bulb </a>with a super bright red <a href="http://www.cree.com/products/pdf/xlampxp-e.pdf">Cree XP-E</a> LED. For the front lamp, I wasn't satisfied with the way my LED bulb sat in the reflector, so designed a heat sink that could be clamped into the opening of the reflector with set screws:<br />
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<a href="http://1.bp.blogspot.com/-WZUlTG6RABs/TyX5ljGXQ5I/AAAAAAAADKE/IcmCbjQuWC8/s1600/luxor+heat+sink.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="335" src="http://1.bp.blogspot.com/-WZUlTG6RABs/TyX5ljGXQ5I/AAAAAAAADKE/IcmCbjQuWC8/s400/luxor+heat+sink.jpg" width="400" /></a></div>
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Here it is machined in copper:<br />
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<tr><td class="tr-caption" style="text-align: center;">Heat sink for Luxor 65 LED upgrade</td></tr>
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and with a Cree XM-L LED mounted directly to the nub that pokes through a slot milled in the PCB:<br />
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<a href="http://3.bp.blogspot.com/-5KEQAszDrE8/T7eqyusUCSI/AAAAAAAAEEA/dFGDgztL9Jc/s1600/IMG_5336.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://3.bp.blogspot.com/-5KEQAszDrE8/T7eqyusUCSI/AAAAAAAAEEA/dFGDgztL9Jc/s640/IMG_5336.JPG" width="640" /></a></div>
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The holes for the set screws weren't quite in the right place to grab the base of the reflector so I had to drill and tap new ones for a 4-40 set screw. Here's how the LED/heat sink assembly clamps onto the base of the reflector:<br />
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<a href="http://3.bp.blogspot.com/-dvx5uDxQzUo/T7eqtm7MfoI/AAAAAAAAEDo/kbIUQOqscKQ/s1600/IMG_5340.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://3.bp.blogspot.com/-dvx5uDxQzUo/T7eqtm7MfoI/AAAAAAAAEDo/kbIUQOqscKQ/s640/IMG_5340.JPG" width="640" /></a></div>
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<tr><td class="tr-caption" style="text-align: center;">Original set screw hole was in the wrong spot!</td></tr>
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Here's how the original bulb holder fits:<br />
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<a href="http://1.bp.blogspot.com/-Tue1Ve9FvR4/T7eqvmuNzTI/AAAAAAAAED4/TUJUc529pM0/s1600/IMG_5342.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://1.bp.blogspot.com/-Tue1Ve9FvR4/T7eqvmuNzTI/AAAAAAAAED4/TUJUc529pM0/s640/IMG_5342.JPG" width="640" /></a></div>
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Notice the double dip in the middle of the edge of the reflector base. I failed to notice this when placing the holes for the set screws!<br />
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The final result:<br />
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<a href="http://3.bp.blogspot.com/-_kPawchVdcc/T7eqf9PmXsI/AAAAAAAAEDA/nx6Yp8av4PM/s1600/IMG_5316.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://3.bp.blogspot.com/-_kPawchVdcc/T7eqf9PmXsI/AAAAAAAAEDA/nx6Yp8av4PM/s640/IMG_5316.JPG" width="640" /></a></div>
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<a href="http://4.bp.blogspot.com/-22kwb4YRTEM/TyS76LqFaJI/AAAAAAAADGQ/d5gJG9j0JpI/s1600/IMG_5317.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="478" src="http://4.bp.blogspot.com/-22kwb4YRTEM/TyS76LqFaJI/AAAAAAAADGQ/d5gJG9j0JpI/s640/IMG_5317.JPG" width="640" /></a></div>
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The light is bright and very floody, much like my <a href="http://minisystem.blogspot.com/2012/01/sturmey-archer-headlight-cree-xm-l.html">LED upgrade to the Sturmey Archer headlight</a>. The beam does not produce a concentrated hot spot, which makes me wonder if this is a limitation of using LEDs with 100-140º viewing angles in reflectors designed for incandescent bulbs with >180º spreads. Some lux data will be required to sort this out.<br />
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Here's the matching Le Martelé rear lamp with a<a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html"> LED bulb</a> replacement:<br />
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<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com6tag:blogger.com,1999:blog-3561798115215934165.post-3806067499830937132012-01-29T22:22:00.000-05:002012-05-19T10:12:21.954-04:00Sturmey Archer headlight Cree XM-L power LED upgrade<div class="separator" style="clear: both; text-align: center;">
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-QDP_XNbvU4U/TyVvfzqGm8I/AAAAAAAADJQ/h1ExZh_Gc5s/s1600/superbe+lamp.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="396" src="http://1.bp.blogspot.com/-QDP_XNbvU4U/TyVvfzqGm8I/AAAAAAAADJQ/h1ExZh_Gc5s/s640/superbe+lamp.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Raleigh Superbe's Sturmey Archer headlight. Photo by <a href="http://www.flickr.com/photos/lowercasedesign/">lowercase design</a></td></tr>
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I really like the Sturmey Archer lamps that equipped later model <a href="http://minisystem.blogspot.com/2011/09/ode-to-raleigh-superbe-and-its-dynohub.html">Raleigh Superbes</a>. The older Raleighs (and other <a href="http://sheldonbrown.com/english-3.html">English 3 speeds</a>) seem to have come with a variety of different lamp styles over the years. My best guess is that when the Superbe hit North American shores in full force in the late 1960s and throughout the 1970s, Raleigh/Sturmey Archer had standardized their lamp offerings, which resulted in the now classic chromed bullet head lamp and tail lamp. This version of the lamp set is what I see most commonly on the streets of Toronto, as well as in <a href="http://www.flickr.com/search/?q=raleigh%20superbe">Flickr feeds.</a> They aren't especially rare and certainly don't show the craftsmanship and quality of the earlier French lamps, but a Sturmey Archer light set can still command prices of well over $100 on Ebay. They can even occasionally be found as a <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-lamps-second-attempt.html">NOS</a>.</div>
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The output from the incandescent bulb is rather pathetic. This is mostly due to the low output from the Sturmey Archer Dynohub that typically powers the lamp, possibly exacerbated by the seemingly low quality of the reflector. Halogen replacements are available from <a href="http://www.reflectalite.com/halogenpage.html">Reflectalite</a>, but even these are rated at a rather paltry 18 lumens. I tried<a href="http://minisystem.blogspot.com/2008/07/dynamo-lithium-ion-battery-charging.html"> upgrading the bulb with an screw base LED replacement</a>, but found the output rather disappointing. I even went to the trouble of making a custom <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">screw base power LED mounted on a copper heat sink</a>. This produced a big floody beam, but the flimsy bulb holder that mounts the bulb in the reflector probably wasn't up to the task of supporting the extra weight of the power LED's heat sink.</div>
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So, back to the drawing board. To start, I thought I'd replace the flimsy stamped bulb holder with a copper heat sink. The reflector is made of coated metal, so it shouldn't have any problem with carrying the weight of the heat sink, which can be wedged into the opening in the reflector in the same fashion as the original bulb holder. This time I decided to use the super high output Cree <a href="http://www.cree.com/products/pdf/xlampxm-l.pdf">XM-L</a>, which is rated at <a href="http://search.digikey.com/ca/en/products/XMLAWT-00-0000-0000T6053/XMLAWT-00-0000-0000T6053CT-ND/2451238">290 lumens @ 700 mA</a>. As in my previous designs for the Cree XPG, a nub pokes through the PCB so the LED's thermal pad can be soldered directly to the heat sink. Something like this:</div>
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<tr><td class="tr-caption" style="text-align: center;">Design for Sturmey Archer headlight heat sink</td></tr>
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Looks a bit like a top hat. Here it is machined in copper:</div>
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<tr><td class="tr-caption" style="text-align: center;">Copper heat sink for Sturmey Archer headlight power LED upgrade</td></tr>
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It flares out a tiny bit where the bottom of the pillar meets the rim. Here's the heat sink with a Cree XM-L soldered on to it:</div>
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This is how the original bulb holder fits in the reflector:</div>
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and here is the copper heat sink mounted in the same opening:</div>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-d1Sj6dr7PbI/T7epO27xlLI/AAAAAAAAECg/Oe6zBtcFtzw/s1600/IMG_5321.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-d1Sj6dr7PbI/T7epO27xlLI/AAAAAAAAECg/Oe6zBtcFtzw/s640/IMG_5321.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Copper heat sink mounted in reflector of Sturmey Archer headlight</td></tr>
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It fits very snugly in the reflector and doesn't feel like it's going anywhere. A dab of Loctite wouldn't hurt though. The LED sits low in the reflector, about where the original bulb's filament would be.</div>
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<tr><td class="tr-caption" style="text-align: center;">Sturmey Archer headlight with Cree XM-L power LED upgrade on copper heat sink</td></tr>
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Coupled with an <a href="http://minisystem.blogspot.com/2011/12/upgrading-wedge-base-bulb-in-sturmey.html">upgraded LED bulb for the rear lamp </a>and a <a href="http://minisystem.blogspot.com/2011/12/sturmey-archer-dynohub-magnet-upgrade.html">Dynohub magnet upgrade</a>, a modern and powerful dynamo system emerges. It will eventually even be possible to add a <a href="http://minisystem.blogspot.com/2011/12/flashing-dynamo-light-prototype.html">standlight and flasher</a>. The lamp is still a victim of its original optics, which obviously aren't nearly as good as the highly optimized optics of modern bike lights, but the high output of the Cree XM-L does result in a bright, floody beam. Certainly enough for cruising around city streets in relative safety and quite possibly enough to illuminate a poorly lit country bike path.<br />
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I'm thinking of making this LED upgrade available, along with <a href="http://minisystem.blogspot.com/2011/12/upgrading-wedge-base-bulb-in-sturmey.html">an LED upgrade for the matching taillight</a>. Let me know if you're interested either by commenting or by emailing me directly (bottom of page).<br />
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The XM-L can be run at up to 3A to produce a whopping 943 lumens so a battery powered retrofit could produce an impressive amount of light, although it remains to be determined if the heat sink would be adequate. That would require some <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">performance testing</a>.</div>
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<br /></div>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com5tag:blogger.com,1999:blog-3561798115215934165.post-78676962705630332072012-01-27T23:33:00.000-05:002012-01-28T10:49:40.365-05:00Programming an Attiny10 with AVRISP mkII and AVR Studio 5Jump to <a href="http://minisystem.blogspot.com/2012/01/programming-attiny10-with-avrisp-mkii.html#attiny10tutorial">Attiny10 programming tutorial</a> if you want to skip my long winded preamble.<br />
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I've been tinkering with my<a href="http://minisystem.blogspot.com/2011/12/flashing-dynamo-light-prototype.html" style="color: #68c520; font-weight: bold; text-decoration: none;"> dynamo powered LED flasher circuit</a> recently. While the standlight works well, the blinking circuit requires that a 5W Zener diode shunt all 500-600 mA of dynamo current during the off cycle of the flash. At a frequency of about 2 Hz and a duty cycle of about 50%, I didn't think this would be a problem, but the damn Zener hits 100°C within a minute and showed no signs of slowing down, suggesting that I was taking it to within an inch of its life. I got some advice about using <a href="http://sound.westhost.com/appnotes/an007.htm" style="color: #68c520; font-weight: bold; text-decoration: none;">a power transistor to shunt the current</a>, but using a 20W transistor still resulted in the device getting too hot too fast. I don't have room to put a big heat sink on it so I finally gave up on trying to shunt the current and getting rid of the off cycle energy as heat. I'm sure there is an elegant solution out there that allows the energy to be recaptured rather than wasted, but I'm already running the rear red LED close to its maximum current. Instead, I decided that I could do away with a flashing front light and just flash the rear light. This way, the dynamo is never disconnected from the load and the Zener does not need to shunt any current except in the case of a connection failure. A low side N-FET seems to do the trick, shorting out the red LED when the transistor is on:<br />
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<tr><td><a href="http://1.bp.blogspot.com/-ueIvMzhMLis/TyBC9Hcc-hI/AAAAAAAADFo/xStF_TS63Qo/s1600/IMG_5314.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="378" src="http://1.bp.blogspot.com/-ueIvMzhMLis/TyBC9Hcc-hI/AAAAAAAADFo/xStF_TS63Qo/s640/IMG_5314.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">N-MOSFET shorts red LED when ON<br />
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Anyway, in the process I also decided that I wanted a flash that was below 50% duty cycle. Ideally around 30% or so to better mimic the strobe pattern of commercial LED flashers. You can <a href="http://www.kpsec.freeuk.com/555timer.htm#dutycycle" style="color: #68c520; font-weight: bold; text-decoration: none;">achieve this with a 555 by adding a diode</a>, but I thought I'd try using a microcontroller to generate the flasher's pulse instead. Why, you might ask, would I want to do something so complicated? Adding a microcontroller to a bike light seems kind of overkill. Well, it turns out I can do it in a smaller package with fewer parts for less money (and learn something along the way). Win!<br />
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In my previous design I was using a 555 astable oscillator to generate the pulse. The smallest package size is SOIC8, which is pretty bulky as far as surface mount devices go. The smallest microcontroller I could find was the <a href="http://www.atmel.com/dyn/products/product_card.asp?part_id=4558" style="color: #68c520; font-weight: bold; text-decoration: none;">Atmel AVR Attiny10</a> that comes in a breathtakingly small SOT23-6 package.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-Y7kYbvNwxPM/TyA94YoQDAI/AAAAAAAADFc/m1lzIjz8UHw/s1600/IMG_5293.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://1.bp.blogspot.com/-Y7kYbvNwxPM/TyA94YoQDAI/AAAAAAAADFc/m1lzIjz8UHw/s640/IMG_5293.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">TI CMOS SOIC8 555 timer ($1.72) next to SOT23-6 Attiny10 ($0.89)</td></tr>
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Surface mount devices are pretty annoying for prototyping, but the advantage of their tiny footprints becomes readily apparent when you need to cram a lot of parts into a small pace. Once I realized how useful SMDs are for creating physically small circuits, I accepted that the prototyping complications were worth it. Getting the Attiny10 onto a breadboard requires a little adapter from the nice people at <a href="http://www.proto-advantage.com/store/" style="color: #68c520; font-weight: bold; text-decoration: none;">Proto-Advantage</a>. I soldered it using a soldering iron. Not as tricky as it seems.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-nKRPydvCu3k/TyA9Kn1kK2I/AAAAAAAADEY/RWoMZa655tQ/s1600/IMG_5289.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://2.bp.blogspot.com/-nKRPydvCu3k/TyA9Kn1kK2I/AAAAAAAADEY/RWoMZa655tQ/s640/IMG_5289.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Attiny10 on SOT23-6 to SIP board</td></tr>
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<span style="font-size: x-large;"><a href="http://www.blogger.com/blogger.g?blogID=3561798115215934165" name="attiny10tutorial"></a>
<span style="color: #999999; font-family: Arial, Helvetica, sans-serif;"><b>Attiny10 programming tutorial</b></span></span><br />
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The Attiny10 part of the Atmel AVR family. The Attinies are the baby siblings of the microcontrollers that are used in the <a href="http://arduino.cc/" style="color: #68c520; font-weight: bold; text-decoration: none;">Arduino</a> development platform. You can even program <a href="http://hlt.media.mit.edu/?p=1695" style="color: #68c520; font-weight: bold; text-decoration: none;">some of the Attinies with the Arduino</a>, such as the Attiny85.<br />
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Unfortunately, the Attiny10 (and variants 4/5/9) won't work with the Arduino IDE and it isn't <a href="http://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=102177&start=0">entirely clear if you can compile C for it,</a> leaving assembler (ASM) as the most straightforward option for programming the whopping 1024 bytes of Flash ROM. It took me a few days of fiddling around to get an Attiny10 to put out a pulse to blink my LEDs. I've put together a little tutorial about programming the Attiny10 to fill in the blanks I found in online documentation, both official and in forums and the blogosphere. Perhaps this will make things a little easier on the very rare occasion that another layperson might want to program an Attiny10 using the available Atmel tools.<br />
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[rant]<br />
Engineers seem to, rather annoyingly, assume that everyone using their products or protocols is also an engineer and their technical documentation reflects this assumption. They seem to communicate by some Borg-like collective knowledge (otherwise known as an Engineering Degree) that is mostly impenetrable to the rest of us. This is often a barrier to the minority of wannabe engineers who want to occasionally parachute into the engineering world to get something specific done without actually becoming, you know, an<i> engineer.</i><br />
[/rant]<br />
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This is a tutorial aimed at programming the Attiny10 in assembler using the Atmel <a href="http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3808" style="color: #68c520; font-weight: bold; text-decoration: none;">AVRISP mkII </a>programmer and <a href="http://www.atmel.com/microsite/avr_studio_5/default.asp?category_id=163&family_id=607" style="color: #68c520; font-weight: bold; text-decoration: none;">AVR Studio 5</a>. By extension, it should also work for all members of the Attiny4/5/9/10 family. It really is just about connecting the Attiny10 to the AVRISP and being able to load hex code onto it because even this can be a frustrating challenge for the uninitiated. The <a href="http://www.atmel.com/dyn/resources/prod_documents/doc8127.pdf" style="color: #68c520; font-weight: bold; text-decoration: none;">Attiny10 datasheet</a>, the AVR <a href="http://www.atmel.com/dyn/resources/prod_documents/doc1022.pdf" style="color: #68c520; font-weight: bold; text-decoration: none;">Assembler User Guide</a> and <span id="goog_1888869009"></span><a href="http://www.atmel.com/dyn/resources/prod_documents/doc0856.pdf">Instruction Se<span id="goog_1888869010"></span>t</a> are wonderfully indecipherable documents that you need to refer to for actual programming in assembler. There is also this <a href="http://www.avr-asm-tutorial.net/avr_en/" style="color: #68c520; font-weight: bold; text-decoration: none;">huge tutorial</a>.<br />
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Adding to the confusion is the fact that there are numerous accounts that AVR Studio 5 is either incompatible with the AVRISP mkII, the Attiny10 or both. As of January 2012, I can say that AVRISP mkII, AVR Studio 5 and Attiny10 all play nicely together on Windows 7.<br />
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So, let's start:<br />
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<b style="color: #999999; font-family: Arial, Helvetica, sans-serif;"><span style="font-size: x-large;">Step One: Get what you need</span></b><br />
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You need an <a href="http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3808" style="color: #68c520; font-weight: bold; text-decoration: none;">AVRISP mkII</a> programmer, <a href="http://www.atmel.com/microsite/avr_studio_5/default.asp?category_id=163&family_id=607" style="color: #68c520; font-weight: bold; text-decoration: none;">AVR Studio 5</a> and some <a href="http://search.digikey.com/ca/en/products/ATTINY10-TSHR/ATTINY10-TSHRCT-ND/2136158">Attiny10s</a> to get programming. A breadboard and a SOT23-6 to <a href="http://www.proto-advantage.com/store/product_info.php?products_id=2400054" style="color: #68c520; font-weight: bold; text-decoration: none;">SIP</a>/<a href="http://www.sparkfun.com/products/717" style="color: #68c520; font-weight: bold; text-decoration: none;">DIP</a> adapter will also come in handy.<br />
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There are a bunch of AVR programmers out there. I chose to use the AVR branded one, the AVRISP mkII, which is a little pricer than the <a href="http://www.ladyada.net/make/usbtinyisp/" style="color: #68c520; font-weight: bold; text-decoration: none;">USBTinyISP</a> but requires no assembly. One gentleman was so averse to using the available Atmel tools that he made <a href="https://sites.google.com/site/wayneholder/attiny-4-5-9-10-assembly-ide-and-programmer" style="color: #68c520; font-weight: bold; text-decoration: none;">his own programmer and his own IDE</a>.<br />
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AVR Studio 5 is a rather huge and cumbersome piece of software that I'm sure is great for managing complicated multi-thousand line projects written in C. <a href="http://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=102177&start=0">You may or may not be able to compile C for the Attiny10</a>, but you can definitely use AVR Studio to write assembler and use the very handy simulator to debug your code before flashing your Attiny.<br />
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I'm pretty sure you could also use AVR Studio 4, which is now mature. In fact, many people seem to have delayed upgrading to AVRS5 because it is considered buggy.<br />
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I'm sure you could also use <a href="http://www.bsdhome.com/avrdude/">avrdude</a> instead of AVR Studio. It has been <a href="http://irq5.wordpress.com/2010/07/15/programming-the-attiny10/">documented</a> to work with the Attiny10. I have a strong aversion to command line interfaces, so avrdude was out (dead give away that I'm not an engineer...).<br />
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<b style="color: #999999; font-family: Arial, Helvetica, sans-serif;"><span style="font-size: x-large;">Step Two: Connect the programmer</span></b><br />
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After downloading and installing AVR Studio 5 you should be able to connect the AVRISP mkII to your PC and see a green light glow inside, next to the USB connector. An exterior LED is red to indicate that there is no external power (weirdly, the AVRISP, despite having Vcc and GND connections, cannot be used to power the Attiny during programming).<br />
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Confusingly, the Attiny10 and its ilk are not programmed using the same 3 wire MISO/MOSI/SCK <a href="http://www.atmel.com/dyn/resources/prod_documents/doc0943.pdf" style="color: #68c520; font-weight: bold; text-decoration: none;">ISP</a> protocol used by other AVR microcontrollers. Instead, they use the 2 wire <u>T</u>iny <u>P</u>rogramming <u>I</u>nterface, or <a href="http://www.atmel.com/dyn/resources/prod_documents/doc8373.pdf" style="color: #68c520; font-weight: bold; text-decoration: none;">TPI</a>. What wasn't at all clear to me from the various documentation available was how you connect the AVRISP mkII to an Attiny10. The <a href="http://www.atmel.com/dyn/resources/prod_documents/AVRISPmkII_UG.pdf" style="color: #68c520; font-weight: bold; text-decoration: none;">AVRISP mkII User Guide</a> makes no mention of TPI. The mkII is documented as being compatible with the Attiny10, but I had to really hunt around to confirm the pin connections from the programmer to the Attiny10.<br />
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Pin connections from <a href="http://www.nongnu.org/avrdude/user-manual/avrdude_20.html" style="color: #68c520; font-weight: bold; text-decoration: none;">here</a><br />
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<table style="background-color: white; color: black;"><tbody>
<tr><td width="20%"><b>AVRISP mkII</b></td><td width="20%"><b>Target</b></td><td width="20%"><b>ATTINY10</b></td></tr>
<tr><td width="20%"><b>connector</b></td><td width="20%"><b>pin name</b></td><td width="20%"><b>pin number</b></td></tr>
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<tr><td width="20%"><b>1 MISO</b></td><td width="20%"><b>TPIDATA</b></td><td width="20%"><b>1</b></td></tr>
<tr><td width="20%"><b>2 VCC</b></td><td width="20%"><b>VCC</b></td><td width="20%"><b>5</b></td></tr>
<tr><td width="20%"><b>3 SCK</b></td><td width="20%"><b>TPICLK</b></td><td width="20%"><b>3</b></td></tr>
<tr><td width="20%"><b>4 MOSI</b></td><td width="20%"><b>–</b></td><td width="20%"><b>–</b></td></tr>
<tr><td width="20%"><b>5 RESET</b></td><td width="20%"><b>RESET</b></td><td width="20%"><b>6</b></td></tr>
<tr><td width="20%"><b>6 GND</b></td><td width="20%"><b>GND</b></td><td width="20%"><b>2</b></td></tr>
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<a href="http://itp.nyu.edu/physcomp/images/tutorials/programmingc/image/isp/avrisppinout.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="242" src="http://itp.nyu.edu/physcomp/images/tutorials/programmingc/image/isp/avrisppinout.jpg" width="400" /></a></div>
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The programmer's Pin 1 is opposite to the red mark on the cable and is marked with a hard-to-see arrow/triangle. I hooked it up wrong the first time, so double check that you've identified pin 1 correctly!</div>
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<tr><td class="tr-caption" style="font-size: 13px;"><span style="font-family: Times, 'Times New Roman', serif;">AVRISP mkII connected to Attiny10</span></td></tr>
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<tr><td><a href="http://4.bp.blogspot.com/-hDNRIH4L5b0/TyA-LF2K7HI/AAAAAAAADEo/P9T51XTbDGw/s1600/IMG_5298.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="478" src="http://4.bp.blogspot.com/-hDNRIH4L5b0/TyA-LF2K7HI/AAAAAAAADEo/P9T51XTbDGw/s640/IMG_5298.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;"><span style="font-family: Times, 'Times New Roman', serif;">From left to right: (1)MOSI/TPIDATA, (2)GND, (3)TIPCLK, (5)VCC, (6)RESET</span></td></tr>
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You need to connect an external 1.8-5.5V power source to VCC and GND before you can program the Attiny10. The programmer's exterior LED will go from red to green when it senses the external power. I use a 3.7V lithium ion battery for power.</div>
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<b style="color: #999999; font-family: Arial, Helvetica, sans-serif; text-align: -webkit-auto;"><span style="font-size: x-large;">Step Three: Program the Attiny10</span></b></div>
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Launch AVR Studio 5 and make a new assembler project: <span style="font-family: Arial, Helvetica, sans-serif;">File:New Project... </span>In the dialog select the AVR Assembler Project template. Then select Attiny10 from the Device Selection dialog that pops up. Write your code (I wanted to blink an LED, so I grabbed and modified some ASM I found <a href="http://www.attiny.com/assembly.htm">here</a> - if you follow that link note that the Attiny10 has PORTB instead of PORTD). This performs a nested decrement of registers. Two registers for the ON delay and three registers for the OFF delay (ie. longer OFF time than ON time). This is what my code looks like:</div>
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<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">rjmp</span> RESET <span style="color: green;">;go and set up PORTB as an output</span> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><br /></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><span style="color: green;">;name registers (selected >r15 arbitrarily)</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">.def</span> counter1 = r16</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">.def</span> counter2 = r17</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">.def</span> counter3 = r18 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><br /></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><span style="color: green;">;set some variables</span> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;time1 and time2 set the value for the final loop in each delay</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><span style="color: blue;"> .equ</span> time1 = 170 <span style="color: green;">;between 0 and 255</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">.equ</span> time2 = 1</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">.equ</span> led = 2 <span style="color: green;">;LED at PB2</span> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">RESET: <span style="color: green;">;set PB2 as an output in the Data Direction Register for PORTB</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">sbi</span> DDRB, led <span style="color: green;">;connect LED to PB2 (Attiny10 pin 4)</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">flash: </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;main loop</span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><br /></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">cbi</span> PORTB, led <span style="color: green;">;LED off - cbi/sbi swapped for N-FET switching (ie.LED is OFF when FET is ON)</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">ldi</span> counter2, time1 <span style="color: green;">;load counter1 delay </span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">rcall</span> onDelay </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">sbi</span> PORTB, led <span style="color: green;">;LED on </span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">ldi</span> counter3, time2 <span style="color: green;">;load counter3 delay</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">rcall</span> offDelay</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">rjmp</span> flash <span style="color: green;">;return to beginning of loop</span></span><br />
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<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">onDelay: </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">clr</span> counter1 <span style="color: green;">;clear counter1</span> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><br /></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">loop1: <span style="color: green;">;nested loop that decrements counter 1 (255) x counter2 (time1) times (ie. 255*time1)</span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">dec</span> counter1 </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;decrement counter1</span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">brne</span> loop1 </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;branch if not 0</span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">dec</span> counter2 </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;decrement counter2</span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">brne</span> loop1 </span><span style="color: green; font-family: 'Courier New', Courier, monospace; font-size: large;">;branch if not 0</span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">ret</span> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">offDelay: <span style="color: green;">;same as onDelay but with a third loop </span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">clr</span> counter1</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">clr</span> counter2 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"><br /></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;">loop2: <span style="color: green;">;decrement counter 1(255) x counter2(255) x counter3(time2) (ie. 255*255*time2) </span></span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">dec</span> counter1</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">brne</span> loop2 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">dec</span> counter2</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">brne</span> loop2 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">dec</span> counter3 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">brne</span> loop2 </span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: large;"> <span style="color: blue;">ret</span> </span><br />
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This is pretty rudimentary. It basically just kills time by pushing bits around registers. A more elegant solution would be to set up an interrupt triggered by the Attiny10's <a href="http://www.atmel.com/dyn/resources/prod_documents/doc2505.pdf">16 bit timer</a> (more on that another time).</div>
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Build your code by selecting <span style="font-family: Arial, Helvetica, sans-serif;">Build:Build Solution</span>. This converts the ASM to machine code. If it builds successfully it will generate a .hex file in the project's folder. This is the file you need to load onto the Attiny10. You can simulate your code by going to <span style="font-family: Arial, Helvetica, sans-serif;">Debug:Start Debugging and Break</span> and and then hitting F10 to step through the instructions and looking at how the contents of registers and ports change, etc.</div>
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When satisfied, you program the chip using <span style="font-family: Arial, Helvetica, sans-serif;">Tools:AVR Programming</span>. Select AVRISP mkII in the Tool drop down list and Attiny10 in the Device list. TPI will come up in the Interface list by default. Click 'Apply'. If there is a connection problem, you will discover it here. This is the time to make sure that the Attiny has its own power and is connected to the AVRISP correctly.</div>
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<a href="http://1.bp.blogspot.com/-CWaUvH8Oskk/TyA-yzENDGI/AAAAAAAADFA/ekE4aBie_kc/s1600/AVRStudio+programming.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-CWaUvH8Oskk/TyA-yzENDGI/AAAAAAAADFA/ekE4aBie_kc/s1600/AVRStudio+programming.png" /></a></div>
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Go to Memories and click '...' to select your project's .hex file if the contents of the Flash box aren't pointing to it already. Then click 'Program'. The programmer will load the code and then you can test it out.<br />
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I found that the programmer needed to be reset by unplugging it from USB and then reconnecting it before I could get each upload to run properly on the Attiny10. I chose PB2 (pin 4) to blink my LED because it isn't connected to any programmer lines, but the other lines should work even if connected to the programmer, so long as it has USB power. If the programmer is off then the Attiny10 didn't like being connected to it. Once satisfied with your program you can disconnect the programer lines and operate it stand alone:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-W0ynyLejT3Y/TyA-mjRfekI/AAAAAAAADE4/ch9TadEvxpc/s1600/IMG_5300.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="478" src="http://1.bp.blogspot.com/-W0ynyLejT3Y/TyA-mjRfekI/AAAAAAAADE4/ch9TadEvxpc/s640/IMG_5300.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Attiny10 blinking an LED</td></tr>
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These are the two sites I found most useful for learning the ins and outs of Attiny10 programming:<br />
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<a href="http://irq5.wordpress.com/2010/07/15/programming-the-attiny10/">http://irq5.wordpress.com/2010/07/15/programming-the-attiny10/</a><br />
<a href="https://sites.google.com/site/wayneholder/attiny-4-5-9-10-assembly-ide-and-programmer">https://sites.google.com/site/wayneholder/attiny-4-5-9-10-assembly-ide-and-programmer</a><br />
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There's also information scattered all over the <a href="http://www.avrfreaks.net/index.php?name=PNphpBB2&file=index">avrfreaks forums</a>.</div>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com2tag:blogger.com,1999:blog-3561798115215934165.post-66452910122314103232012-01-17T17:57:00.000-05:002012-01-17T17:57:06.427-05:00Beautiful retro styled lights by Kimura from Jitensha StudioBrowsing around today I came across <a href="http://www.jitensha.com/eng/kimura_lights.html">these</a> for the first time:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://www.jitensha.com/eng/images/kimuraheadlt_400.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="345" src="http://www.jitensha.com/eng/images/kimuraheadlt_400.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kimura flashlight</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://www.jitensha.com/eng/images/kimuratail_400t.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="351" src="http://www.jitensha.com/eng/images/kimuratail_400t.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kimura tail lamp</td></tr>
</tbody></table>
They are <a href="http://www.jitensha.com/eng/kimura_lights.html">Kimura lights</a> from <a href="http://www.jitensha.com/">Jitenshi Studio</a>, a bicycle shop in Japan that specializes in high quality touring and randonneuring bikes. The lights are handmade by one Mr. Kimura. They're not inexpensive ($195 USD for the flashlight, $125 for the taillight), but the quality looks amazing, easily rivalling similarly priced offerings by <a href="http://www.nabendynamo.de/english/index.html">Schmidt</a> or <a href="http://www.supernova-lights.com/en/">Supernova</a>, but with infinitely more retro charm. Too bad Mr. Kimura isn't in the business of making dynamo lights.<br />
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Mounting a vintage flashlight on a front rack seems to be a popular way to dress up your vintage (or modern classical) touring/randonneuring bike. Historically I think these flashlights served as auxiliary lighting for bottle dynamo systems when stopped. Here is a particularly gorgeous example from the <a href="http://store.velo-orange.com/">Velo-Orange </a>site:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://store.velo-orange.com/media/catalog/category/lights_header.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="209" src="http://store.velo-orange.com/media/catalog/category/lights_header.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Vintage flashlight on a bike. Image from <a href="http://store.velo-orange.com/">Velo-Orange</a>.</td></tr>
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The tail lamp is especially intriguing. I wonder if the lens is pulled from a mass-produced light or if it was made specially for this application. They also have a nice selection of reflectors.<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0tag:blogger.com,1999:blog-3561798115215934165.post-77172983241373562822012-01-02T17:31:00.000-05:002012-01-02T17:31:48.699-05:00Dynamo digital buck converter: progress reportInspired by this<a href="http://www.candlepowerforums.com/vb/showthread.php?316815-peak-power-trackers-for-bike-dynamos"> thread at CPF</a>, I built a prototype of a <a href="http://minisystem.blogspot.com/2011/11/specific-aim-2-dynamo-digital-buck.html">digital buck converter</a> using the <a href="http://arduino.cc/">Arduino</a> development platform. The point of it is to extract more power out of a hub dynamo without adding extra LEDs in series. To rehash: modern hub dynamos typically saturate at about 500-600 mA and their voltage is primarily determined by the load, so the easiest way to passively get more power of them is to add more LEDs in series. Each LED gets the same current in the series circuit, while Vf of the whole series circuit goes up by the forward voltage of each additional LED. White LEDs typically have forward voltages of about 3V, and most hub dynamos easily put out 6V at low speeds, making this a viable arrangement. Even 3 series LEDs with a Vf of 9V can produce a lot of light at low speeds, although the minimum speed that reaches Vf will, of course, be higher than with fewer LEDs. However, I'm primarily interested in single LED designs for retrofitting into vintage lamp housings. With proper heat sinking some white power LEDs can take well over 1A. In order to extract more current out of the hub we need a buck converter that converts the higher voltage available from the dynamo at higher speeds into more current for the LEDs. This is done by switching the buck converter with pulse widths below 100% duty cycle. Here's the schematic:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-OETipbHcajw/TujsVvpnVCI/AAAAAAAAC1U/kuridKH12cY/s1600/buckconverter.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="333" src="http://3.bp.blogspot.com/-OETipbHcajw/TujsVvpnVCI/AAAAAAAAC1U/kuridKH12cY/s640/buckconverter.png" width="700" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Schematic for Arduino-controlled digital buck converter for hub dynamo</td></tr>
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This is a <a href="http://en.wikipedia.org/wiki/Buck_converter#Synchronous_rectification">synchronous</a> buck converter that uses two switches rather than a single switch and diode. This increases efficiency by reducing switching losses (ie. the voltage drop across the diode). <a href="http://ww1.microchip.com/downloads/en/DeviceDoc/22083a.pdf">MCP14628</a> is a MOSFET driver specifically designed for digitally controlled SMPSs; when UGATE is high, LGATE is low and there's a buil charge pump to drive the high side FET. The <a href="http://arduino.cc/en/Tutorial/SecretsOfArduinoPWM">PWM</a> signal comes from the Arduino. This circuit worked <a href="http://minisystem.blogspot.com/2011/11/specific-aim-2-dynamo-digital-buck.html">fine</a> with a bench top power supply, taking a higher voltage input and converting it to a higher current at Vf of the series LEDs. However, when I connected it to a dynamo Q1 kept getting fried. This was probably due to Vdyn (rectified DC dynamo input) spiking when the load is disconnected while Q1 is off, exceeding Q1's maximum Vgs. I added D3 to take care of this (Vgs(max) of these FETs is 30V). Despite this, I still would occasionally fry Q1. C3 and D2 were added to protect the high side FET from getting zapped by exceeding its Vgs, this time perhaps due to parasitic inductance of the long wires in my messy breadboarded prototype. C3 and D2 seem to work and during normal operation Q1 doesn't get fried anymore. However, when the load is disconnected or I mistakingly set the duty cycle to 0% in the software, Q1 gets toasted. I asked for help <a href="http://forum.allaboutcircuits.com/showthread.php?p=438247">here</a>, and am starting to get some answers. Making C3 larger might be a good start. It is situations like this one where my complete lack of electrical engineering training becomes a bit of a barrier to progress...<br />
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The <a href="http://diodes.com/zetex/_pdfs/3.0/pdf/ZXCT1009.pdf">ZXCT1009</a> is a high side current monitor that is used as feedback for the PWM signal.<br />
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Here's what it looks like on the breadboard:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-UPvPUpfiE4w/TpG509fIX-I/AAAAAAAACqE/Or9HJiKqgyU/s1600/IMG_20110920_164712.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://4.bp.blogspot.com/-UPvPUpfiE4w/TpG509fIX-I/AAAAAAAACqE/Or9HJiKqgyU/s640/IMG_20110920_164712.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Buck converter spaghetti!</td></tr>
</tbody></table>
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Pretty messy, which is certainly reducing efficiency. Once it's tidily committed to a PCB I hope the efficiency will go up a bit and there won't be as many issues with parasitic inductance. I'd also like to double the switching frequency from 32 KHz to 64 KHz so I can use a smaller inductor.<br />
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Here's how my buck converter performs with 2 series LEDs with a Vf of about 5V powered by a <a href="http://www.peterwhitecycles.com/sanyo.asp">Sanyo H27 dynamo</a>:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-u2kDnGtQtdI/Tugb4g0bpVI/AAAAAAAACzk/cG2-BQcfB_8/s1600/sanyo+buck+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="498" src="http://4.bp.blogspot.com/-u2kDnGtQtdI/Tugb4g0bpVI/AAAAAAAACzk/cG2-BQcfB_8/s640/sanyo+buck+data.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Current versus speed of a dynamo powered buck converter at different duty cycles. Switching frequency is 32 KHz</td></tr>
</tbody></table>
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The advantage of dropping the duty cycle appears just over 20 km/h, although it is quite modest. Above 30 km/h I think the converter is getting a worthwhile amount of extra power, roughly 200 mA (1W or about 40% more). Efficiency is roughly 80%. I need to test other duty cycles and perhaps go below 50%. Thus far it seems like there's not much peak power tracking to be done. A simple implementation would be to leave the duty cycle at 100% below 20 km/h and then drop it to 50% above that. The H27 saturates at around 500 mA, whereas other hub dynamos saturate at slightly higher currents. Perhaps they also have better low speed performance and if they can generate a higher output voltage at lower speed then there might be more of an advantage to using a buck converter.<br />
<br />
There is<a href="http://swhs.home.xs4all.nl/fiets/tests/verlichting/dynamo_led_driver/index_en.html"> another microcontroller-based dynamo LED driver </a>out there. Its <a href="http://swhs.home.xs4all.nl/fiets/tests/verlichting/dynamos/dynamos.gif">performance</a> seems to be considerably better than mine; it produces surprising amounts of power at low speeds, whereas mine can only begin to harvest more power out of the hub just before it saturates. To be fair, because of my specific application, I am measuring current into two series LEDs rather than total power output, so this is a bit of an apples to oranges comparison. However, there is no denying that this converter seems to perform better at speeds below 30 km/h. I naively speculate that its <a href="http://en.wikipedia.org/wiki/Switched-mode_power_supply">switching topology</a> is something other than buck, but really I have no idea how it's done or how complicated or expensive the implementation is.<br />
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I'm not entirely sure if the complication of a buck converter is worth the effort. <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.html">Human perception of brightness</a> is commonly described as logarithmic, meaning that a linear increase in actual luminous flux does not result in a correspondingly linear increase in the <a href="http://neuroelec.com/2011/04/led-brightness-to-your-eye-gamma-correction-no/">perceived brightness</a>. I've not really found this put very succinctly on the Internet, so this might be an oversimplification (and hopefully not entirely incorrect). <br />
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Whether or not this whole exercise is mostly academic remains to be determined...<br />
<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com4tag:blogger.com,1999:blog-3561798115215934165.post-8358019182673600562011-12-30T17:35:00.000-05:002011-12-31T11:41:22.662-05:00Sturmey Archer Dynohub magnet upgrade: progress report<div class="separator" style="clear: both; text-align: left;">
I <a href="http://minisystem.blogspot.com/2011/11/specific-aim-4-dynohub-magnet-upgrade.html">designed</a> a magnet adapter to hold 20 neodymium magnets in the same positions as the poles of the original Sturmey Archer GH6 Dynohub ring magnet. The first adapter I made was for 0.125" block magnets. This adapter worked <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-dynohub-magnet-upgrade.html" style="text-align: -webkit-auto;">better than I expected</a><span class="Apple-style-span">, more than doubling the power output available from the original magnet. Well, it turns out that, after calibrating my current monitor, the upgraded magnets work even better than I first thought, nearly tripling the dynamo's power output. In a short-circuit current reading on my multimeter, the upgraded hub saturates at around 1.0A! Running two power LEDs in series, it gets to around 0.9A at about 45 km/h. </span></div>
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<span class="Apple-style-span">Great. However, this is actually probably more power than I need. While white power LEDs can take well over 1A, the </span><a href="http://minisystem.blogspot.com/2011/12/upgrading-wedge-base-bulb-in-sturmey.html" style="text-align: -webkit-auto;">brightest red LEDs I want to use in tail lamps</a><span class="Apple-style-span"> are rated at a maximum of 700 mA. I think I need to tone it down a bit and try to get that saturation current below 0.7A. The other incentive to do this is to reduce the drag. Spinning the wheel by hand in the testing jig doesn't give the impression there is much more resistance from the new magnets, but spinning the armature itself on the upgraded hub is much harder than with the original magnet. So, I designed a new adapter that places 20 0.0625 (1/16)" magnets with the same spacing from the armature (about 0.04"). The sixteenth inch magnets are N40s instead of the N42 eighth inch magnets and they are a lot cheaper. This time I got them from these </span><a href="http://magnet4us.com/" style="text-align: -webkit-auto;">fine folks</a><span class="Apple-style-span">, just north of Toronto. As before, they are epoxied on with JB-Weld.</span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-p_3ErkrEbnw/TvfjzIVXTJI/AAAAAAAAC_E/X1iH5GD0H64/s1600/IMG_5153.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://2.bp.blogspot.com/-p_3ErkrEbnw/TvfjzIVXTJI/AAAAAAAAC_E/X1iH5GD0H64/s400/IMG_5153.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dynohub magnet adapter with 1/16" Nd magnets in place</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-umTjUIy_YlI/TvfmrdsCdrI/AAAAAAAAC_I/9zrm4dOVB0Y/s1600/IMG_5154.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://3.bp.blogspot.com/-umTjUIy_YlI/TvfmrdsCdrI/AAAAAAAAC_I/9zrm4dOVB0Y/s400/IMG_5154.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Here's how it fits over the armature</td></tr>
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I fitted this into the Dynohub wheel on my <a href="http://minisystem.blogspot.com/2011/11/specific-aim-3-dynamo-wheel-testing-jig.html">motorized testing jig</a> and measured the current at different speeds, logging the data with an <a href="http://arduino.cc/">Arduino</a>:<br />
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<a href="http://2.bp.blogspot.com/-KesWbUS8GRk/Tvkz0DK2mqI/AAAAAAAADAE/H5L5MNp2OMw/s1600/IMG_5215.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="http://2.bp.blogspot.com/-KesWbUS8GRk/Tvkz0DK2mqI/AAAAAAAADAE/H5L5MNp2OMw/s640/IMG_5215.JPG" width="640" /></a></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-e0wuXJON11w/TvlV-iZUK6I/AAAAAAAADAM/9EpmGSXur1Y/s1600/GH6+upgrade+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="504" src="http://3.bp.blogspot.com/-e0wuXJON11w/TvlV-iZUK6I/AAAAAAAADAM/9EpmGSXur1Y/s640/GH6+upgrade+data.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Current versus speed of GH6 Dynohub</td></tr>
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<div style="text-align: center;">
<div style="text-align: left;">
The 1/16" magnets seem to be just about right. At 45 km/h the hub hits just over 700 mA, although it doesn't look like it's quite plateaued. I might be wise to incorporate some back up current limiting circuitry to protect my red LED at very high speeds. The resistance from the 1/16" magnets is about as much as you'd expect from a contemporary hub dynamo. Based on these results, I think I'm going to stick with 1/16" magnets. They're cheaper, easier to install, offer less resistance and produce a peak current that is mostly suitable for the red LEDs I want to use.<br />
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The current design leaves the magnets a little exposed. I doubt they'd ever come loose, even in the exceptional case of contact with the armature. Still, I've designed a new version of the magnet holder that leaves them less exposed:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-MOwpQF3NtFk/Tvym_8Q7BZI/AAAAAAAADAw/Wodp1-gxz4E/s1600/magnet+holder+0625+slots+drawing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="497" src="http://1.bp.blogspot.com/-MOwpQF3NtFk/Tvym_8Q7BZI/AAAAAAAADAw/Wodp1-gxz4E/s640/magnet+holder+0625+slots+drawing.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Proposed protective magnet holder</td></tr>
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</div>
It's more complicated than my current design, so will be more expensive. The exterior machining is to reduce the weight, but it doubles the price. This should weigh about 190 grams. Without the outside machining, it would weigh about 270 grams. Not sure if the extra cost is worth the reduced weight...<br />
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I could also get it made out of aluminium, which would make it very light and a little less expensive. The advantage of using steel is that the magnets stick to it and the attraction acts as a clamp while the epoxy sets. An aluminium adapter would require that each magnet be individually clamped to prevent them from jumping out of their slots and sticking to one another.<br />
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<br /></div>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com3tag:blogger.com,1999:blog-3561798115215934165.post-85912331068530971832011-12-27T14:07:00.000-05:002011-12-27T14:07:09.458-05:00Upgrading the wedge base bulb in a Sturmey Archer tail lampI'm quite partial to the bullet-shaped tail lamps that were part of the <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-lamps-second-attempt.html">Sturmey Archer Dynohub lighting set</a> (and I'm not the <a href="http://minisystem.ca/light_thief.html">only one</a>). While the head lamp takes a standard E10/MES screw base bulb, the taillight takes a <a href="http://www.sjscycles.co.uk/6v-01a-capless-bulb-for-sturmey-archer-rear-lights-hsd-410-prod13136/">hard-to-find</a> <a href="http://en.wikipedia.org/wiki/Wedge_base">wedge base bulb</a>. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-k59wOFoDvIg/TvfucXhxQjI/AAAAAAAADAg/bci_LRXP9E0/s1600/IMG_5167.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="http://4.bp.blogspot.com/-k59wOFoDvIg/TvfucXhxQjI/AAAAAAAADAg/bci_LRXP9E0/s320/IMG_5167.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Original capless wedge base bulb. Get 'em while you can at <a href="http://www.sjscycles.co.uk/6v-01a-capless-bulb-for-sturmey-archer-rear-lights-hsd-410-prod13136/">sjscycles</a>.</td></tr>
</tbody></table>
<br />
When I <a href="http://minisystem.blogspot.com/2008/07/dynamo-lithium-ion-battery-charging.html">converted my first set</a> of Sturmey Archer lamps to LEDs, I resorted to soldering a jumbo leaded LED onto a piece of PCB that I could wedge into the the bulb holder. Now, in order to take advantage of the extremely bright red <a href="http://www.cree.com/products/pdf/xlampxp-e.pdf">Cree XP-E</a>, I used a slightly modified version of my <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">E10/MES LED heat sink</a> to make a wedge base LED bulb. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://media.digikey.com/Photos/Cree%20Photos/XPERED-L1-R250-00701.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="200" src="http://media.digikey.com/Photos/Cree%20Photos/XPERED-L1-R250-00701.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cree XP-E red. 131 lumens @ 0.7A!</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-uL_9M8QoKCw/TvkznFDRy7I/AAAAAAAAC_4/QzihKkhOvuY/s1600/IMG_5204.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="http://4.bp.blogspot.com/-uL_9M8QoKCw/TvkznFDRy7I/AAAAAAAAC_4/QzihKkhOvuY/s400/IMG_5204.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Copper heat sink for red Cree XP-E</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-qyWEWnZKgvg/TvkzrYpKwnI/AAAAAAAAC_8/l7RT19vUFME/s1600/IMG_5209.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="http://4.bp.blogspot.com/-qyWEWnZKgvg/TvkzrYpKwnI/AAAAAAAAC_8/l7RT19vUFME/s400/IMG_5209.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">LED board and wedge base board.</td></tr>
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The copper heat sink has a #4-40 tapped hole to mount a rectangular piece of PCB perpendicular to the LED platform with a machine screw. Wires come through the heat sink platform and are soldered to the wedge contacts:<br />
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<a href="http://4.bp.blogspot.com/-XgFlLU3KYoM/TvfnygalFuI/AAAAAAAAC_M/RSzgNUgfXY8/s1600/IMG_5156.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="http://4.bp.blogspot.com/-XgFlLU3KYoM/TvfnygalFuI/AAAAAAAAC_M/RSzgNUgfXY8/s400/IMG_5156.JPG" width="400" /></a></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-w7JkVUrF7P0/Tvfn95bFQ6I/AAAAAAAAC_Q/fcIWT_v9KWg/s1600/IMG_5157.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="http://2.bp.blogspot.com/-w7JkVUrF7P0/Tvfn95bFQ6I/AAAAAAAAC_Q/fcIWT_v9KWg/s400/IMG_5157.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Completed wedge base bulb with copper heat sink and red Cree XP-E</td></tr>
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To get a good fit in the lamp's spring contacts I added a blob of solder at the base of each contact, on both sides. A tight fit is essential as the heat sink assembly is much heavier than the original glass bulb.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-pdQziNJyKc8/TvfrCZRnOWI/AAAAAAAAC_U/P740aOKXyeI/s1600/IMG_5163.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://2.bp.blogspot.com/-pdQziNJyKc8/TvfrCZRnOWI/AAAAAAAAC_U/P740aOKXyeI/s400/IMG_5163.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Original bulb and Cree XP-E replacement bulb mounted in lamp</td></tr>
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<a href="http://3.bp.blogspot.com/-wEhd258lvDI/TvfrKsukHaI/AAAAAAAAC-w/omuE9_H_Icc/s1600/IMG_5164.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="http://3.bp.blogspot.com/-wEhd258lvDI/TvfrKsukHaI/AAAAAAAAC-w/omuE9_H_Icc/s400/IMG_5164.JPG" width="400" /></a></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-HZ_nwfyVQ1Y/TvfuLr5or7I/AAAAAAAAC-0/kf7AT4GNGoU/s1600/IMG_5165.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://3.bp.blogspot.com/-HZ_nwfyVQ1Y/TvfuLr5or7I/AAAAAAAAC-0/kf7AT4GNGoU/s400/IMG_5165.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The beautiful bullet!</td></tr>
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The Cree XP-E has a maximum current rating of 0.7A. In a passive dynamo system, it'll get up to 0.6A, so I'll need to ensure that the heat sinking is sufficient. Unlike my <a href="http://minisystem.blogspot.com/2011/12/copper-based-led-bulb-fitting-and.html">screw base LED bulb</a>, there isn't really any thermal connection between the heat sink and the bulb base, preventing much heat transfer to the lamp body. I'm hoping that it will run up to 0.7A in <a href="http://minisystem.blogspot.com/2011/12/flashing-dynamo-light-prototype.html">flashing mode</a>, the off time lowering the steady state heat sink temperature.</div>
<br />minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0tag:blogger.com,1999:blog-3561798115215934165.post-28377839484817287112011-12-22T16:03:00.000-05:002011-12-22T23:45:46.467-05:00Flashing dynamo light prototypeAs I've <a href="http://minisystem.blogspot.com/2011/09/tail-lamps-to-flash-or-not-to-flash.html">discussed previously</a>, I'd like to build a dynamo powered lighting system with a powerful standlight and the option of having the lights flash. This is a feature that doesn't seem to be available on commercially available dynamo lighting systems, which don't flash and typically have rather weak standlights. It took me a long time to develop the circuit and I got a lot of help from the fine people on <a href="http://candlepowerforums.com/">CPF</a>, particularly in this <a href="http://www.candlepowerforums.com/vb/showthread.php?319330-555-based-dynamo-powered-flasher-circuit">thread</a>. After a couple of months of tinkering I had a working circuit breadboarded. It charges a 20F supercapacitor using a <a href="http://minisystem.blogspot.com/2011/09/charging-supercapacitors.html">current limiting load switch</a> and uses a<a href="http://diodes.com/zetex/_pdfs/3.0/pdf/ZXSC310.pdf"> Zetex boost driver</a> to power the LEDs while stopped. A high side P-channel MOSFET switches the LEDs between dynamo power and capacitor power and a low-side N-channel MOSFET is used to flash the LEDs with the output of a (special low-voltage CMOS) <a href="http://en.wikipedia.org/wiki/555_timer_IC">555 timer</a>.<br />
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Now the challenge was to turn the breadboarded circuit into something that could fit into the housing of a vintage lamp. This is what I started with:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-7psiDDcaQAs/TvNymCW5hTI/AAAAAAAAC9U/YZZa_CZN0YM/s1600/IMG_5136.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://3.bp.blogspot.com/-7psiDDcaQAs/TvNymCW5hTI/AAAAAAAAC9U/YZZa_CZN0YM/s640/IMG_5136.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Breadboarded dynamo circuit with standlight.</td></tr>
</tbody></table>
First, I needed to capture the schematic:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-W87-8VZ76aI/TvNzHqP07vI/AAAAAAAAC8A/XlIbnAb4YR4/s1600/dynamolight.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="186" src="http://2.bp.blogspot.com/-W87-8VZ76aI/TvNzHqP07vI/AAAAAAAAC8A/XlIbnAb4YR4/s640/dynamolight.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Schematic of flashing dynamo standlight circuit (click to enlarge)</td></tr>
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I used <a href="http://www.cadsoftusa.com/">EagleCAD</a> to do this, which is a very capable and free piece of schematic capture and PCB layout software. Most of the components I had to make in my own custom library, which I'll eventually post someday. Most standard packages (SOT23, 0805, SOIC, etc) are already available. I placed the parts as logically as I could and used the autorouter, which did a pretty darn good job of routing everything in a circle about 1.6" in diameter. My design rules included larger minimum trace widths and more generous spacing around components than the default rules. After much revision, I wound up with a two-sided PCB design:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-WCYk9SF475A/TvNz3JmSZEI/AAAAAAAAC8s/hKzYuLjX_YU/s1600/dynamoPCB.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://1.bp.blogspot.com/-WCYk9SF475A/TvNz3JmSZEI/AAAAAAAAC8s/hKzYuLjX_YU/s400/dynamoPCB.png" width="396" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">PCB layout in EagleCAD</td></tr>
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Sparkfun has an excellent PCB layout <a href="http://www.sparkfun.com/tutorials/109">tutorial</a> using EagleCAD. I sent the Gerbers off to <a href="http://batchpcb.com/index.php/Products">BatchPCB</a> and a few weeks later received the boards:<br />
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<a href="http://2.bp.blogspot.com/-UYLQGk-AEbw/TvN1ZjsCkHI/AAAAAAAAC9Y/2ApK-X2lwS8/s1600/IMG_5139.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="http://2.bp.blogspot.com/-UYLQGk-AEbw/TvN1ZjsCkHI/AAAAAAAAC9Y/2ApK-X2lwS8/s400/IMG_5139.JPG" width="400" /></a></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-VxVHSWECBFc/TvN1alp36yI/AAAAAAAAC9c/YSlNqOzRzfI/s1600/IMG_5140.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://1.bp.blogspot.com/-VxVHSWECBFc/TvN1alp36yI/AAAAAAAAC9c/YSlNqOzRzfI/s400/IMG_5140.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">BatchPCB boards. Not bad for $3 each!</td></tr>
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Now came the hard part. In order to keep things small I chose all surface mount parts. I don't have much experience soldering SMT components, but there are several tutorials on Youtube plus some from <a href="http://www.sparkfun.com/tutorials/96">Sparkfun</a>. After a couple of hours I felt I had the hang of it and wound up with a reasonably good looking board. For most components I used a soldering iron and occasionally would resort to using a hot air rework station.<br />
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<a href="http://4.bp.blogspot.com/-fVyWhBO6wtQ/TvNyfT-XROI/AAAAAAAAC8w/wjnIZJLOt0g/s1600/IMG_5132.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="http://4.bp.blogspot.com/-fVyWhBO6wtQ/TvNyfT-XROI/AAAAAAAAC8w/wjnIZJLOt0g/s400/IMG_5132.JPG" width="400" /></a></div>
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<a href="http://4.bp.blogspot.com/-uhOxieFhRAs/TvNygVyx8AI/AAAAAAAAC9A/siQBjXOXR7c/s1600/IMG_5133.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="http://4.bp.blogspot.com/-uhOxieFhRAs/TvNygVyx8AI/AAAAAAAAC9A/siQBjXOXR7c/s400/IMG_5133.JPG" width="400" /></a></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-rn6NDbMONfs/TvNyjPf3R3I/AAAAAAAAC9E/0sh7_7tX8cM/s1600/IMG_5135.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://3.bp.blogspot.com/-rn6NDbMONfs/TvNyjPf3R3I/AAAAAAAAC9E/0sh7_7tX8cM/s400/IMG_5135.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Populated PCB. Huge 20F supercapacitor dominates!</td></tr>
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It really wasn't as bad as I thought it would be. Fine tweezers are essential! Having a stereomicroscope didn't hurt either (all the time I spent dissecting fruit fly larvae brains and injecting zebrafish embryos is finally paying off...).<br />
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To my amazement, the whole thing worked on the first try. The only problem was that I didn't include an input capacitor for the 555 timer which I had on the breadboard. Without it, the 555's output is very erratic while the supercapacitor is charging. I soldered a 10µF leaded capacitor across pin 1 (GND) and pin 8 (Vcc) of the 555 and it worked exactly as it did on the breadboard. Revision 1.1 of the PCB will have to correct that!<br />
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The 6.8V Zener, which regulates the input voltage, gets darned hot as it shunts all the dynamo current during the off cycle in flashing mode. This could cause a potential failure of the Zener. I need to test it extensively to see if it fails. If it does, then I'll have to figure out what to do with the dynamo voltage when the LEDs are disconnected during the off period of the flash. No ideas yet.<br />
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Another potential pitfall is that the LEDs are connected in series, so if the rear light becomes disconnected, the series circuit will be broken and the front light won't work. The advantage of being in series is that both LEDs get the same current, simplifying the standlight circuit. For now, I think it's a good compromise.minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com1tag:blogger.com,1999:blog-3561798115215934165.post-18446189011102079112011-12-21T18:03:00.000-05:002011-12-21T18:12:30.799-05:00Sturmey Archer GH6 Dynohub magnetic keeper ringThe Sturmey Archer Dynohub 'Keeper Ring' has become the stuff of legends. Frequently mentioned in discussions about <a href="http://www.sheldonbrown.com/dynohubs.html">servicing the Dynohub</a> but never described, it is as rare as hens teeth. It is, apparently, essential to maintain the GH6 ring magnet's field strength during circumstances in which the armature needs to removed. A <a href="http://www.google.ca/search?q=dynohub+keeper+ring">google search</a> did turn up one on <a href="http://www.worthpoint.com/worthopedia/sturmey-archer-dynohub-keeper-ring-167204771">auction</a> back in February, which even included a photograph:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-zIgO92efgWk/TvJVAsWjo_I/AAAAAAAAC6o/I1Aly8Z6_R0/s1600/keeperring.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="316" src="http://3.bp.blogspot.com/-zIgO92efgWk/TvJVAsWjo_I/AAAAAAAAC6o/I1Aly8Z6_R0/s320/keeperring.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The only photograph of a Dynohub keeper ring I could find on the <a href="http://www.worthpoint.com/worthopedia/sturmey-archer-dynohub-keeper-ring-167204771">internet</a></td></tr>
</tbody></table>
<br />
<i>Update: just after posting this I found a wealth of information on the keeper ring in this <a href="http://www.bikeforums.net/showthread.php/718697-Sturmey-Archer-Dynohub-keeper-ring?highlight=dynohub+keeper+ring">thread</a> on bike forums, including dimensions and part number!</i><br />
<br />
Other than infrequently turning up on eBay, they are unavailable. <a href="http://3speedtour.com/">Gentleman Cyclist</a> does, however, mention on their <a href="http://www.home.earthlink.net/~steinborn/gentlemancyclistmerchandise.htm">parts page</a> that they will soon have keeper rings for the Dynohub (you should take a look at the other interesting bits and bobs they carry for the 3-speed enthusiast).<br />
<br />
Well, I had an old Dynohub from '75 that was rusty as all heck. It came from a trashed ladies Raleigh Superbe that was languishing in the basement of <a href="http://www.yelp.ca/biz/pollys-recycle-toronto">Polly's Recycle</a> in the east end. The armature could barely spin within the ring magnet and the whole assembly was covered in a coat of rusty grit. Usually a Dynohub can be serviced without the need for removing the armature from the ring magnet, but in this particular hub's case, the armature need a good going over with a wire brush. So, I had my <a href="http://www.east-master.com/en/home/index.asp">Internet Material Synthesizer</a> make one out of mild steel #45. Now, I think my <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-dynohub-magnet-upgrade.html">Dynohub magnet upgrade </a>makes the original magnet kind of obsolete, but I was getting a bunch of other parts made so I thought I'd get a keeper ring made as well. It arrived today:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-0sRgINRC32Y/TvJdjE23aCI/AAAAAAAAC7M/Ii9hfPEqlLI/s1600/IMG_5122.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://2.bp.blogspot.com/-0sRgINRC32Y/TvJdjE23aCI/AAAAAAAAC7M/Ii9hfPEqlLI/s400/IMG_5122.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Machined Dynohub Keeper Ring</td></tr>
</tbody></table>
<br />
It has a 2.700" outer diameter, the same as the armature, and is 0.75" thick.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-67zpNlzKoes/TvJUbAiIibI/AAAAAAAAC7U/3roZAhrT6tk/s1600/IMG_5113.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://3.bp.blogspot.com/-67zpNlzKoes/TvJUbAiIibI/AAAAAAAAC7U/3roZAhrT6tk/s400/IMG_5113.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dynohub Alnico ring magnet with armature. Don't remove that magnet without a keeper!</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-sM1phFTnPSM/TvJUYL2_VgI/AAAAAAAAC7Y/52d56le_h-I/s1600/IMG_5112.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="http://4.bp.blogspot.com/-sM1phFTnPSM/TvJUYL2_VgI/AAAAAAAAC7Y/52d56le_h-I/s400/IMG_5112.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dynohub ring magnet with keeper</td></tr>
</tbody></table>
<br />
<br />
Does it work? I don't know. I pushed the armature out with the keeper, so the field wasn't disrupted. The magnet feels about as strong as it did before the armature was removed. The design is very similar to the original, so I expect it's doing its job. <br />
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Do you want one? I can easily get more made. They would cost between $15-$30 each, depending on number I get made in one go. I'm also thinking of offering a <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-dynohub-magnet-upgrade.html">magnet upgrade</a> for the Dynohub (this is still a work in progress though...)<br />
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If you're interested send me an email (find the address in my <a href="http://www.blogger.com/profile/02307045935296201366">profile</a>).minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com3tag:blogger.com,1999:blog-3561798115215934165.post-37895066453128604322011-12-18T11:50:00.000-05:002011-12-18T18:39:55.493-05:00Copper-based LED bulb fitting and performance testingI must admit that I was rather enamoured with the elegant design of the finned copper heat sink I had made. Unfortunately, it <a href="http://minisystem.blogspot.com/2011/12/hot-led-lux-readings-of-cree-xp-g-on.html">didn't actually perform as well as I'd hoped</a>, so I revised the design with the aim of getting the LED lower in the parabola of the reflector and giving up on improving the thermal properties (which were just OK). This is basically just a chopped down version of the previous design with a larger hole through the centre and a couple of countersunk holes on the top to ensure complete electrical isolation from the PCB.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-gb8X1vwg7IA/Tu1ylUGTvyI/AAAAAAAAC3M/2X7ie_AhltU/s1600/pillar_drawing.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="372" src="http://4.bp.blogspot.com/-gb8X1vwg7IA/Tu1ylUGTvyI/AAAAAAAAC3M/2X7ie_AhltU/s400/pillar_drawing.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Revised LED bulb pillar heat sink design</td></tr>
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The <a href="http://www.east-master.com/en/home/index.asp">Internet Material Synthesizer</a> took about 10 days to make this:<br />
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<a href="http://1.bp.blogspot.com/-QLAin0Rl9qI/Tu5KZQ4ea8I/AAAAAAAAC34/OagJp1XAUEI/s1600/IMG_5102.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="http://1.bp.blogspot.com/-QLAin0Rl9qI/Tu5KZQ4ea8I/AAAAAAAAC34/OagJp1XAUEI/s400/IMG_5102.JPG" width="400" /></a></div>
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I soldered the Cree XP-G LED (still tricky even with a <a href="http://www.sparkfun.com/products/10706">hot air rework station</a>), ran the wires and used a thermal epoxy to stick it into an E10/MES Edison threaded bulb base:<br />
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<a href="http://2.bp.blogspot.com/-7FTga1WpMPs/Tu5JWsr8YZI/AAAAAAAAC4A/OQTtutyk4Bw/s1600/IMG_5085.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="http://2.bp.blogspot.com/-7FTga1WpMPs/Tu5JWsr8YZI/AAAAAAAAC4A/OQTtutyk4Bw/s400/IMG_5085.JPG" width="400" /></a></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-GgZkrsaYmlM/Tu5JdEiEopI/AAAAAAAAC4E/GcFfOZjfEXE/s1600/IMG_5089.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://3.bp.blogspot.com/-GgZkrsaYmlM/Tu5JdEiEopI/AAAAAAAAC4E/GcFfOZjfEXE/s400/IMG_5089.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">E10/MES Edison LED bulb with copper heat sink</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: left;">
This can now be threaded into any flashlight or vintage bike lamp that takes a miniature screw bulb (albeit in need of a separate driver circuit). I first tried it out in a <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-lamps-second-attempt.html">Sturmey Archer head lamp</a>:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-DHqcULbU3Ro/Tu5KGcnNvII/AAAAAAAAC4M/yVbUF49EKV0/s1600/IMG_5099.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://2.bp.blogspot.com/-DHqcULbU3Ro/Tu5KGcnNvII/AAAAAAAAC4M/yVbUF49EKV0/s400/IMG_5099.JPG" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Flimsy bulb holder of SA headlight </td></tr>
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Unfortunately, the SA lamp has a rather low quality and flimsy way of mounting the bulb in the reflector. The actual bulb holder is a thin piece of stamped metal that doesn't hold the bulb straight. This is then pressed in and held by friction in the base of the reflector, where the positive bulb end makes contact with a springy metal tab:</div>
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<a href="http://2.bp.blogspot.com/-tt9JDzeRvEc/Tu5KOwV0ATI/AAAAAAAAC4Q/vGWJ4SvgPfA/s1600/IMG_5100.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="http://2.bp.blogspot.com/-tt9JDzeRvEc/Tu5KOwV0ATI/AAAAAAAAC4Q/vGWJ4SvgPfA/s400/IMG_5100.JPG" width="400" /></a></div>
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The switch quality is terrible and even a NOS lamp had enough oxidation on the contacts to make switching finicky and provided enough resistance that getting the full current available current from the power supply wasn't possible. So, the original switch and contacts are useless. I'll have to retrofit a higher quality switch on the bottom of the lamp and leave the original switch purely for aesthetics.<br />
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Ok, so I've given up on fitting a screw bulb into the original holder of the SA head lamp. I think I can design something that can be pressed (and maybe epoxied) into the reflector. It will be simpler, won't rely on the flaky original contacts and will probably have better thermal properties.<br />
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So, how does the bulb perform in a decent quality lamp holder? For this, I turned to the trusty and well-designed bulb holder of a <a href="http://www.blogger.com/"><span id="goog_221540746"></span>Luxor<span id="goog_221540747"></span></a> lamp. Conveniently (and unlike SA lamps), both head and tail lights use the same well-made bulb holder:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-iZS9UUCB0Nw/Tu5Z450-5WI/AAAAAAAAC4c/Es5V9GuzyfE/s1600/IMG_5106.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://4.bp.blogspot.com/-iZS9UUCB0Nw/Tu5Z450-5WI/AAAAAAAAC4c/Es5V9GuzyfE/s400/IMG_5106.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Luxor makes a better bulb holder than Sturmey Archer<br /></td></tr>
</tbody></table>
It uses side springs to snap securely into a the base of the lens, which is then fitted into the lamp body with clips. I drove the LED at different currents from a bench top supply and measured the temperature with my thermocouple-equipped multimeter.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-ifOZEj0wqps/Tu5JwOCkkZI/AAAAAAAAC4I/9lPny1UlZD0/s1600/IMG_5093.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://2.bp.blogspot.com/-ifOZEj0wqps/Tu5JwOCkkZI/AAAAAAAAC4I/9lPny1UlZD0/s400/IMG_5093.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">LED bulb ready for testing! Brown wire is thermocouple.</td></tr>
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Now that I've automated data logging of wheel speed, LED current and <a href="http://minisystem.blogspot.com/2011/12/logging-lux-data-with-hacked-dx-light.html">light output</a>, I should probably just go ahead and make an <a href="http://www.ladyada.net/learn/sensors/thermocouple.html">Arduino-based thermocouple</a> to log temperature as well. However, that hasn't happened yet, so all I did was log lux data over 20 minutes, and make note of the steady state end temperature. <br />
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One requirement of my LED bulb is that it outperform commercially available E10 LED bulbs, so I pitted my bulb against the (I think) now discontinued TerraLUX MiniStar1 TLE-1S (the flanged version still seems to be <a href="http://www.amazon.com/TerraLUX-TLE-1F-MiniStar1-Replacement-Flashlight/dp/B000B868MA">available</a>). It is rated at 50 lumens and is the same bulb that I used in my original (and doomed) <a href="http://minisystem.blogspot.com/2008/07/dynamo-lithium-ion-battery-charging.html">Sturmey Archer LED retrofit.</a> I also tried out the 35 lumen <a href="http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&category=LIGHTS&Page2Disp=%2Fpt%2Fbulbs.html">E10-WHP</a>, but it put out a paltry 6 lux at 1 meter, so I didn't bother logging the data. The TLE-1S is rated 1W with its own built in driver. Given 3.4V, it sucked up 0.35A, so about 1.2W.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-0O-q7FORC84/Tu5ghvqzHZI/AAAAAAAAC48/95MjzG_kJ5E/s1600/tle-1s-011.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-0O-q7FORC84/Tu5ghvqzHZI/AAAAAAAAC48/95MjzG_kJ5E/s1600/tle-1s-011.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The defending champion: TLE-1S</td></tr>
</tbody></table>
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Here are the results:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-j5szBr4ts78/Tu5fBr8hhwI/AAAAAAAAC4k/IFK44meYbf0/s1600/led+bulb+lux+data.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="507" src="http://3.bp.blogspot.com/-j5szBr4ts78/Tu5fBr8hhwI/AAAAAAAAC4k/IFK44meYbf0/s640/led+bulb+lux+data.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lux data (no secondary optics) collected every 30 seconds over twenty minutes. </td></tr>
</tbody></table>
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Great, the TLE-1S gets blown out of the water by my LED bulb. It also got surprisingly hot (74.5°C!), although its output didn't drop much as a consequence. Now, to be fair, I didn't collect data for my bulb at 0.35A, but that's because I have no intention of running it at 0.35A. Ultimately, it will get any one of the three currents tested: 0.5-0.6A from direct dynamo output or 0.75-1A from a <a href="http://minisystem.blogspot.com/2011/11/sturmey-archer-dynohub-magnet-upgrade.html">dynohub magnet upgrade</a> or <a href="http://minisystem.blogspot.com/2011/11/specific-aim-2-dynamo-digital-buck.html">buck driver</a>. Still, speaking as a former scientist, this experiment was not properly controlled...<br />
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Surprisingly, the revised LED bulb performance is better than my <a href="http://minisystem.blogspot.com/2011/12/hot-led-lux-readings-of-cree-xp-g-on.html">original design</a>; although the initial output is about 3-5 lux lower across the board (this could be due to LED-to-LED variability as well as the fact that I burned off the LED dome of my first prototype!), the thermal performance is better, resulting in lower steady state temperatures and, consequently, less light drop. This is probably because the bulb base is in contact with the fairly bulky Luxor bulb holder, which is increasing the surface area by at least two fold. Although the contact area between the bulb base and holder is small it seems to be enough to improve thermal performance.<br />
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Overall, I'm pleased with the result. This bulb will work at high currents in a variety of vintage tail lamps and, at the very least, in the <a href="http://www.flickr.com/photos/10703870@N06/sets/72157624583329882/detail/">Luxor head lamp</a>. Unfortunately, the bulb holders of both the Sturmey Archer head lamp and the <a href="http://homepage3.nifty.com/ClassicBicycles/brands/radios.html">Radios</a> <a href="http://minisystem.blogspot.com/2011/12/vintage-radios-bicycle-lamps.html">No. 18</a> are too flimsy and will require individualized solutions. I think I can design a simple replacement LED/holder combination that won't require any modification to the lamp.<br />
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One problem is that I still think the LED is a little high in the parabola of the Luxor reflector. Not sure how much more length I can shave off my copper pillar while leaving enough room for mounting and wire routing holes...<br />
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<span class="Apple-style-span" style="font-family: 'MS UI Gothic';"><br /></span>minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0tag:blogger.com,1999:blog-3561798115215934165.post-83035734301493308712011-12-15T00:53:00.000-05:002011-12-30T17:05:15.493-05:00Logging lux data with a hacked DX light meter<div style="text-align: left;">
I've been using an <a href="http://www.arduino.cc/en/Main/arduinoBoardUno" style="text-align: -webkit-auto;">Arduino Uno</a><span class="Apple-style-span"> to log data for my <a href="http://minisystem.blogspot.com/2011/11/specific-aim-2-dynamo-digital-buck.html">buck converter project</a>. I've been logging the LED current using a </span><a href="http://www.diodes.com/datasheets/ZXCT1009.pdf" style="text-align: -webkit-auto;">high side current monitor</a><span class="Apple-style-span"> and the wheel speed on my </span><a href="http://minisystem.blogspot.com/2011/11/specific-aim-3-dynamo-wheel-testing-jig.html" style="text-align: -webkit-auto;">testing jig</a><span class="Apple-style-span"> using the pulsed output of the dynamo, which I can count using a clever</span><a href="http://www.atmel.com/dyn/resources/prod_documents/doc2508.pdf" style="text-align: -webkit-auto;"> zero cross detector</a><span class="Apple-style-span"> that is inherent to the inputs of all AVR microcontrollers. The data is sent to a computer via serial interface. Measuring LED current is all well and good, but the real performance measurement is the LED light output, which is not only current dependent, but also </span><a href="http://minisystem.blogspot.com/2011/12/hot-led-lux-readings-of-cree-xp-g-on.html" style="text-align: -webkit-auto;">temperature dependent</a><span class="Apple-style-span">. So, I got a cheap-o </span><a href="http://www.dealextreme.com/p/digital-lux-meter-with-stand-200000lux-5100" style="text-align: -webkit-auto;">digital lux meter</a><span class="Apple-style-span"> from DealExtreme branded as 'Ceto', which allowed me to take a few readings to see how the light output dropped with increased LED temperature. </span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://www.dealextreme.com/productimages/sku_5100_1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://www.dealextreme.com/productimages/sku_5100_1.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">DealExtreme SKU 5100 digital light meter</td></tr>
</tbody></table>
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It would be nice, though, if I could log this data digitally in the same way I can log current and velocity data. I thought there might be a way to decode the signal going to the LCD to get a digital output, but it turns out that this is <a href="http://code.google.com/p/casainho-projects/wiki/SdCardBathroomScale">way complicated</a>, requiring, at the very least, a datasheet for the LCD (and a touch of genius doesn't hurt either). Disappointed, I resorted to looking up the identifiable ICs on the printed circuit board. There are some <a href="http://www.alldatasheet.com/view.jsp?Searchword=CD4070BP">quad gates</a>, <a href="http://www.alldatasheet.com/view.jsp?Searchword=CD4066BP">bilateral switches</a> and a <a href="http://www.nxp.com/documents/data_sheet/HEF4013B.pdf">dual flip flop</a>, which I speculate are involved in analog to digital conversion and range switching. Anyway, there was one lonely 27M2BC dual opamp right by the sensor input that looked promising. The <a href="http://www.ti.com/lit/ds/symlink/tlc27m2b.pdf">datasheet</a> even has a little "Photo-Diode Amplifier" application circuit on page 32.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-9PZIiQ7omn8/Tul9S5c7PyI/AAAAAAAAC2k/E6_gBKX3wHk/s1600/IMG_5053.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="476" src="http://3.bp.blogspot.com/-9PZIiQ7omn8/Tul9S5c7PyI/AAAAAAAAC2k/E6_gBKX3wHk/s640/IMG_5053.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">27M2B opamp on lux meter circuit board</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-A2ZRIUXsvs0/Tul4DJyROTI/AAAAAAAAC24/0ToXC6-0AGE/s1600/IMG_5052.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="476" src="http://3.bp.blogspot.com/-A2ZRIUXsvs0/Tul4DJyROTI/AAAAAAAAC24/0ToXC6-0AGE/s640/IMG_5052.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pin 7 has an output whose voltage matches the lux reading on the LCD</td></tr>
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I probed around a bit to see if the designers had used the same circuit in the datasheet, but quickly found out that this chip didn't have the same pinouts as the label on the package suggested. Maybe it's a counterfeit? The Texas Instruments logo sure does look a bit fuzzy. In any case, I found one pin (pin 7) whose voltage changes with light input, from 0 to about 2.2V. Turns out the lux value displayed on the LCD is a base 10 multiple of the voltage on pin 7, the order of magnitude being determined by the range switch. For example, when in the 2000 lux range, 0.178V = 178 lux:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-xYh8Mkv6Aog/Tul4TPIa0SI/AAAAAAAAC28/GLJLGN-EJPw/s1600/IMG_5069.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="476" src="http://3.bp.blogspot.com/-xYh8Mkv6Aog/Tul4TPIa0SI/AAAAAAAAC28/GLJLGN-EJPw/s640/IMG_5069.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Opamp output voltage is scaled by some factor of 10 to the actual lux reading</td></tr>
</tbody></table>
So, all that needs to be done is to read the voltage on the opamp's pin into the Arduino, multiply according to the range setting and be done with it. The only issue is that my current monitor is read relative to the Arduino's 1.1V internal reference, so any value over 1.1 volts will be clipped by the ADC. This essentially halves the lux value that each range can read, which isn't too big a deal. The default reference of 5V would allow the full range to be measured. <br />
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I put a 3.5 mm mono jack in the front panel to get the signal out to the Arduino:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-0dC0MbMlgDk/Tul4NKMdkTI/AAAAAAAAC3A/AdvJsVTEGa4/s1600/IMG_5062.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://2.bp.blogspot.com/-0dC0MbMlgDk/Tul4NKMdkTI/AAAAAAAAC3A/AdvJsVTEGa4/s640/IMG_5062.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pin 7 is brought out to the front panel via 3.5 mm mono jack</td></tr>
</tbody></table>
Some tweaking in code was required to get an accurate voltage reading. I'm using a <a href="http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1208715493/11">fast ADC conversion</a> on the Arduino, which makes things a little noisier.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-eNIPULGoG0U/Tul4UXL1acI/AAAAAAAAC2E/p2Pk5LdbxHA/s1600/IMG_5072.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="http://2.bp.blogspot.com/-eNIPULGoG0U/Tul4UXL1acI/AAAAAAAAC2E/p2Pk5LdbxHA/s640/IMG_5072.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Arduino pulling data from lux meter</td></tr>
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So, now I'll be able to gather lux data at different speeds!minisystemhttp://www.blogger.com/profile/02307045935296201366noreply@blogger.com0