Electrical – Limit voltage/current of bridge rectifier


Assume I have a small bicycle generator which usually feeds the front and back LED/light bulbs. Powering a small gadget from this generator should well be possible.

The setup would involve a full-wave bridge rectifier followed by some sort of regulator. However, the rectifier output voltage does vary wildly depending on speed and load:

  • low speed and/or high load by lighting: low rectifier output voltage
  • high speed and/or lighting switched off or defective: high output voltage

The first case is non critical and simply means that I need some sort of battery backup and/or a boost converter for hold-up power while going slow or standing.

The second case is more critical since it dictates the voltage rating of regulator and capacitors. And I wonder: Is there a clever way to limit the voltage and or current of a bridge rectifier?

I considered zener diodes but these would dissipate quite a lot of power and I wonder wether there is a more clever way.

Best Answer

Bicycle dynamos use the inductance of the winding to regulate the voltage and, for the recommended load, keep it fairly constant across a wide range of frequencies.

See my answer to Non-LED simple bicycle dynamo light system.