Vermes
Advanced Member level 4
This is the project of a mini-generator for a bike. The light is made of red LEDs. Electromagnet was taken from a big laser printer, three neodymium magnets are from broken computer discs (especially old ones are recommendable, eg. From Seagate 20GB disc – they are big and strong). As it is shown in the pictures, the magnets were screwed to the spokes at equal intervals to minimize the effect of not balancing.
The electromagnet is screwed to the bicycle frame, the distance from the electromagnet core from flying neodymium magnets is about 8mm (not less, because of the beating of wheels). Electromagnet coil was described as dedicated to the 28V, and its resistance is about 180-190ohms. So it is AC. Next, there is a rectifying diode (1A), then 78M05 was put, a 150ohms resistor and three LEDs in parallel.
At first, the idea was to use electrolyte 2200uF before the resistor and LEDs, the light flickered much less, practically continuous light was lighting, but the flashes turned out more visible and provide more security.
All discrete components were placed in a piece of a recycled PCB with few holes screwed on it and 4 paths were made. Then the plate was put in the housing of rear light of the bike (Romet, Gazela) so that the whole does not attract attention.
Link to original thread – Światło rowerowe na friko - mój mini-DIY