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Thread: repairing a Supernova Triple dynamo headlight

  1. #31
    Flashaholic* Steve K's Avatar
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    Default Re: repairing a Supernova Triple dynamo headlight

    hmmm.... actually, you could tap off of the rectified power in the E3, which is indeed the voltage applied to the LEDs. Since the light's power switch is in series with the dynamo power, you would have to have the light turned on in order to charge the battery. To be honest, this wouldn't be a bad arrangement. The battery would absorb most (all?) of the current when it needed to be charged, and then the LEDs would start using more current as the battery charging started to taper off. It wouldn't require the zener diode at all, since the LEDs are effectively clamping the dynamo voltage.



    Being a bit too lazy to go back through the thread and check, I seem to recall that you might have been planning to have the light off while charging the battery. For a lot of other dynamo lights, that might be required. For the Supernova, you might not need to.

    My only concern is that there is a weird low-speed mode on the Supernova, where it uses a buck converter to supply current to the lowest LED. It might still draw current while the battery is charging, so perhaps you'd need to go back and turn off the Supernova, and have a dedicated bridge rectifier and zener for the battery charge circuit. It might take some test runs to see how things work out.

  2. #32

    Default Re: repairing a Supernova Triple dynamo headlight

    Hi, Thanks again - just a quick note to say that I have now designed and ordered a PCB based on the above. Would you like me to send you a populated one to play with when it all arrives?

  3. #33
    Flashaholic* Steve K's Avatar
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    Default Re: repairing a Supernova Triple dynamo headlight

    best wishes with the PCB. Translating a circuit from the schematic to copper can be an adventure and learning experience all by itself! Usually, it's a lesson in why engineers are very detail oriented. It doesn't take much of an oversight to reach an "aw sh*t" moment with circuit boards.
    Fortunately, jumper wires and dremel tools can take care of a lot of these issues.

    Thanks for the offer of a board, but I've got a few projects in the queue already. Need to make a taillight that isn't as horribly ugly as the one I have now, and want to try to fit an optic with a tighter beam into my headlight. ..and then there's that dead B&M Eyc that I want to bring back to life (or use as the base for some experiments.. a bit Frankenstein-ish, perhaps).

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