Simple LED Replacement for Bicycle Bulb / Front Light

Introduction: Simple LED Replacement for Bicycle Bulb / Front Light

I wanted to replace the old inefficient bulb in my Bicycle front light with a simple LED circuit while still using my dynamo for power.

While most bicycle dynamos have something like 6V, 3W written on them, that's not entirely true. Their output is usually limited to 500mA at whichever voltage that might be. This makes them perfect to use with LEDs. The only thing we need is an LED circuit that doesn't mind burning 500mA at whichever voltage that might be ;)

Materials used:

- 2x pieces of wire to connect our circuit to the bulb socket.

- 4x Diodes, strong enough to conduct 500mA each

- 2x 1W LEDs (If 330mA) - but you can use any combination that is capable of conducting 500mA.

- PCB for heat conduction and stability. I used a piece of PCB from a broken ATX power supply


- Solder everything together and attach to your Bicycle.

- Enjoy less pedaling & more light!

I've used this circuit for over 4 months now and it still works perfectly fine.

If you use warm white LEDs it looks like you'd still use a bulb, just that it's way brighter.

Next level experiment:
You could probably drop the rectifier diodes and use LEDs instead (2 parallel in each direction). I'm not sure if the periodic reverse operation will damage the LEDs. Try it and give me some feedback if you like ;)

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    4 Discussions

    Zen Innovations
    Zen Innovations

    2 years ago

    High power LEDs won't last much unless proper heatsinks are used. Using a few resistors to limit current will also help.


    5 years ago on Introduction

    Nice! Thanks for sharing this.

    It would be great if you included a couple shots of this new light on your bicycle. :)


    Reply 5 years ago on Introduction

    Thanks :)

    it's hidden inside the original case, where the bulb was. So there's not much to see there...


    Reply 5 years ago on Introduction

    Ah! That makes sense. Still, very nicely done!