After more then 2 years my old bicycle generator circuit is dying of corrosion. It’s time to rebuild it (and a better enclosure to protect it as well).
I used a full bridge rectifier with a 470uF capacitor at the output side of the rectifier the step down is a cheap module from AliExpress. On the bottom side of the module are soldering pads to select a fixed output voltage, in my case 5V, and the potentiometer must be removed.
I reused the potentiometer to set the brightness of an indicator LED and an ultracap for standby lights.
My current light setup are two 3W LEDs in a cheap metal enclosure. Although not fully powered, with 5V the light output is more than enough for a bicycle.