Run rear light from same dynamo as front

steveo_mcg

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Re: Run rear light off same dynamo as front

10mm diameter x 30mm length.. not too bad. $17USD? a bit pricey for my tastes, which is probably why I keep using a AA nicad cell for my standlights. Sort of a false economy, I suppose, since I add so many hours of labor to put together my little boost converter. I suppose it's better to not think too much about the cost of the personal time when it comes to hobbies like this, though. :)

I try not to think about the cost of my time, even on minimum wage I'd be more economical buying one of those nice German lights. Then again cycling is probably the only hobby to save me both time and money compared with driving or getting the bus to work.

Short note on above: I think 2 in series would give you a 5F 5.4V equivalent, and 2 in parallel would give you a 20F 2.7V equivalent. You'd need to take steps to make sure the caps were not getting more than their V rating in either case.

You're right I have written the above backwards... They're correct in the light though. I'll go back and fix that to avoid confusion.

The measured voltage across the emitter never goes higher that 2.3v when running at 500ma if something causes the voltage to rise above 2.7v I've probably got bigger issues :poof:
 

Steve K

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Re: Run rear light off same dynamo as front

The measured voltage across the emitter never goes higher that 2.3v when running at 500ma if something causes the voltage to rise above 2.7v I've probably got bigger issues :poof:

If "emitter" means "LED", then I'm surprised that you're only getting 2.3v across it. Are we talking about a white LED or a red (or other)? ... I guess that this thread is about a tail light, so I'll assume it's a red LED. That makes the 2.7v supercap much more suitable!

and a note about my earlier post about the cost of the supercap: I took a closer look at the ebay auction, and the price was $17USD for 10 supercaps, not just 1. That's a much better price, but then you have to figure out what to do with the remaining supercaps (every silver lining has a cloud). :)
 

steveo_mcg

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Jan 18, 2010
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Re: Run rear light off same dynamo as front

Aye supercap is across a RED led, yeah I don't think the capacitor would've lasted long across a XR-E.

I've managed to use four two for this and two for an upcoming front still thinking of other mischief I can get up to....
 

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