Hey all. I would like to know if anybody has a circuit for a bicycle light powered by a coil/magnet. One that doesn't blink. As simple as possible. 200 ohm coil puts out about 3.6 volts Thanks in advance.

 

How much wattage does your coil generate? Or amperage at voltage?

 

It will light 4 LEDs at 25ma each, max. That help?

 

Maybe like this:

 

kind of like the old generator driven by the front wheel? there is no way to get it to not blink without a battery, the slower you go, the slower the waveform getting rectified, till the cap discharges between pulses. also a problem with ballancing the wheel with a magnet stuck to it.

 

The only thing simpler I could imagine is using the LEDs as the bridge rectifiers.
I think some current limiting (resistors) will be needed to prevent over-current to the LEDs.

 

It will light 4 LEDs at 25ma each, max. That help?

I think you should try your LED's powered by a battery first. Putting less than 1/2 watt into the LED's will not produce very much light. I gave up on a cheap bike headlight for that reason.

The headlight I ended up building drives the LED's with up to 12 watts. At 2 watts I have to ride at low speeds because of the limited site distance of the dim light.

Be warned that your legs are generating all the power to light the headlight. I chose batteries, rather than a generator, to power the headlight both to relieve the legs and to keep the mechanics simple.

 

Maybe like this:
View attachment 73944

I'm not using a dynamo. A single coil with magnet(s).

 

I think you should try your LED's powered by a battery first. Putting less than 1/2 watt into the LED's will not produce very much light. I gave up on a cheap bike headlight for that reason.

The headlight I ended up building drives the LED's with up to 12 watts. At 2 watts I have to ride at low speeds because of the limited site distance of the dim light.

Be warned that your legs are generating all the power to light the headlight. I chose batteries, rather than a generator, to power the headlight both to relieve the legs and to keep the mechanics simple.

So far with 3 magnets, I don't feel any drag. I am trying to get away from batteries.

 

The only thing simpler I could imagine is using the LEDs as the bridge rectifiers.
I think some current limiting (resistors) will be needed to prevent over-current to the LEDs.

Interesting idea.

 

Ahh, Then one diode a big capacitor and many more magnets.

 

Heed Richard's comments. It's about power. I think ronv is hinting at the same issue.

An old fashioned dynamo gave up to 6W and produced a dim light. That can be improved a bit with LEDs but you still need at least a couple watts, maybe 1A at your coil's 3.6V. (Voltage is proportional to rotational speed, so I'm not sure what "3.6V" really means.)

Your four LEDS at 25mA - assuming you can really operate at that current, that it is well below the maximum spec for the LEDs - will only consume about 3.6V x 0.075A = 0.27W. That's enough to be seen, but not enough to illuminate the path before you.