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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!

7 comments

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bazzargh [151 posts] 5 years ago
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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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bazzargh [151 posts] 5 years ago
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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

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dave atkinson [6214 posts] 5 years ago
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ah, ace. thanks chaps.

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

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Fringe [1047 posts] 5 years ago
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i havent a clue wot yer on about.  4

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!

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Tony Farrelly [2868 posts] 5 years ago
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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  1

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dave atkinson [6214 posts] 5 years ago
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it's race cut  16

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Tony Farrelly [2868 posts] 5 years ago
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not any more it isn't