This is a regulator for a 6V/3W bicycle generator system. The purpose is to switch to rechargeable batteries when the generator is idle. In addition, the device limits the voltage across the bulbs when the generator operates at a high speed.
As you can see, the circuit is purely electrical. In the presented design, the switch has been moved, compared to the original to a location where the switch better functions under different circumstances. I kept the regulator on the bike for 2 years during which the circuit operated fairly satisfactorily. Thereafter, I moved on to an electronic regulator optimized for the operation with a hub dynamo.
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