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A dull question about capacitance

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  • April 13, 2011 at 1:10 pm #13306
    dave atkinson

    Alright roadccers? I’ve been having fun building up my Raleigh 2-spd of late and i’ve got a dynamo hub running some high-output LEDs in natty ’60s light housings. So far so good.

    They’re very flickery though, especially when you’re grinding away in the dark. As it were. Up a hill, i mean.

    my basic understanding of electrical things suggests i need to add some capacitance to the circuit to smooth things out a bit. but i don’t know how much, or where, or anything.

    anyone got any bright ideas? it’s a 6v circuit running from a shimano hub (2.4w), earthed through the frame like off of the old school.

    cheers!

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Viewing 7 replies - 1 through 7 (of 7 total)
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  • April 15, 2011 at 3:59 pm #642533
    0
    Tony Farrelly

    not any more it isn’t
    not any more it isn’t

    April 15, 2011 at 3:35 pm #642531
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    dave atkinson

    it’s race cut
    it’s race cut B-)

    April 15, 2011 at 3:23 pm #642529
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    Tony Farrelly

    I was wondering where that
    I was wondering where that jersey had gone -hope you haven’t gone and stretched it, it not being your size and all.

    They’re on their way Fringe đŸ™‚

    April 13, 2011 at 8:30 pm #642527
    0
    Fringe

    i havent a clue wot yer on
    i havent a clue wot yer on about. đŸ˜€

    btw when are those road.cc jerseys you was wearing on the dragon ride reccie gonna be available to us punters?! i’ll be the toast of bemmie in one of them!

    April 13, 2011 at 3:17 pm #642525
    0
    dave atkinson

    ah, ace. thanks chaps.
    i
    ah, ace. thanks chaps.

    i *think* there’s a rectifier built into the PCB of the LED.

    April 13, 2011 at 2:12 pm #642523
    0
    bazzargh

    These circuit diagrams (with
    These circuit diagrams (with part numbers) may help. They’re all around the right values for what you’re doing. Covers the rectifier and the capacitor. You can buy single-component rectifiers instead-much the same effect.
    http://pilom.com/BicycleElectronics/DynamoCircuits.htm

    April 13, 2011 at 1:56 pm #642521
    0
    bazzargh

    You do have a bridge
    You do have a bridge rectifier in there, right? Dynamos are AC and diodes only work with one direction of current so if you don’t then there’s going to be no light half of the time – very very flickery. And may damage your LED. With the rectifier you might decide you don’t need that capacitor any more.

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