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I'm running my dynohub with a shimano switch/current limiter which appears to be goosed (switches on and off intermittently, whether it is actually switched off or not!).
It seems a replacement is unavailable. Are limiters now integral with headlights?
I was also thinking of wiring up a capacitor for standlight at the back, but am guessing that any DIY attempt will not work as well as the commercially avaliable ones?
Ooof! Off the page in 49 minutes 🙁
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A limiter / standby battery wouldn't be that hard to design & make...
I suspect you could find a design by googling a bit?
I know footflaps, but if it's much more than a couple of components then I CBA and I may as well buy a better light as I'm just running a mudguard light at the mo.
One of these?
[url= http://www.rosebikes.co.uk/article/shimano-overvoltage-protection-sm-dh10/aid:196629 ]Shimano regulator[/url]
Don't think there is any standby in that, looks just like a regulator
Ah well, guilty of answering the question, sorry 🙂
cynic-al - Member
I'm running my dynohub with a shimano switch/current limiter which appears to be goosed (switches on and off intermittently, whether it is actually switched off or not!).
I know footflaps, but if it's much more than a couple of components then I CBA and I may as well buy a better light as I'm just running a mudguard light at the mo.
My guess is you need four components:
A diode bridge rectifier (4 diodes in a module) to go ac to dc (assuming hub dynamo output is ac).
A zener diode as a clamp to limit the voltage, buy a beefy one and glue it to a heatsink.
A battery (NiMh or NiCd) in parallel with the lights.
A switch on the output to turn the lights off.
Possibly a capacitor to smooth the ac to dc, but I reckon you'd get away without it.
Ah well, guilty of answering the question, sorry
Ah, you are as well. Smacks head and retires to cave. I thought the cap was part of it.
Pas du probleme 🙂
If you're looking to limit the current you can use a simple current course you can use a jfet with the gate tide to the drain like this.
http://www2.eng.cam.ac.uk/~dmh/ptialcd/csink/csink.htm
Thanks peeps, that regulator looks OK but is for the rear light only...so I need a front light with a regulator in-built?
My switch has been mostly "on" lately so I'll probs leave it to new year 😛
You could do a lot worse than look on pilom.com, Martin's circuits are a great summary of a few neat ideas that should get you going, and some more complicated ones for the more ambitious:
[url= http://pilom.com/BicycleElectronics/DynamoCircuits.htm ]PILOM.COM DYNAMO CIRCUITS[/url]
It's well worth a look on candlepowerforums too, once you have understood the basics
Happy tinkering. Oh, and you don't need batteries, they're nasty heavy things that need voltage regulation 😉
For a modern front light you don't need regulation - it's only for old lights that have bulbs, where they might blow. I think my b and m light instructions actually said not to fit any regulator. I'm guessing the same is true for rear.
If your regulator has the standlight built in, rather than it being in the rear light unit itself, that is a pain, probably easiest just to buy an led rear light with standlight built in, and maybe a modern front light while you're at it (they are brilliant, you need one).
Alternatively, I have a home made dynamo rear without a standlight, and a cheap flashing light as a backup for junctions, which works fine. So standlight is not vital.
This is a question for the CTC web forum. They had a test of dynamos in the last mag that was uttly indecipherable to the lay man.
The purpose of the regulator was so that, if the front bulb blew, the current surge wouldn't blow the back bulb too (or vice versa). They're not needed for modern LED lights, and in fact I've found the Shimano ones don't play nicely with LEDs sometimes.