A stepper motor is not only a motor that drives all kinds of devices (printer, scanner, etc.), but also a good generator! The main advantage of such a generator is that it does not need high revs. In other words, even at low speeds, the stepper motor generates a lot of energy. That is, an ordinary bicycle generator requires initial revolutions until the lamp starts to shine with bright light. This disadvantage disappears when using a stepper motor. In turn, the stepper motor has several disadvantages. The main one is a large magnetic sticking. Anyway. First we need to find a stepper motor. Here the rule works: The larger the engine, the better. Here I will introduce you to a couple of mounting options and a couple of stepper motor options. Let's start with the biggest. I tore it out of the plotter for printing, it's such a big printer. In appearance, the engine looks quite large.
Before showing you the stabilization and power scheme, I want to show you the method of attachment to your bike.
As can be seen from the figure, our generator is bolted closer to the axis of the wheel and rotates from an additional circle. Here you need a thought and ingenuity. Each of you needs to come up with a mount and a circle of rotation yourself, since there are a lot of options.
Here is another option with a smaller engine.
I think each of you during the construction will choose the most suitable option for him.
Well, now it's time to talk about flashlights and power circuits. Naturally, all the lights are LED.
The rectification scheme is usual: a block of rectifying diodes, a pair of large capacitors and a voltage regulator.
Typically, 4 wires corresponding to two coils come out of a stepper motor. Therefore, there are two rectifier blocks in the figure.
Our generator is capable of producing up to 50 volts of voltage at high speeds, therefore, capacitors must be taken to a voltage of at least 50. And a stabilizer for 5-6 volts. What is our homemade good ?! - The fact is that even when starting off, our lamp shines brightly! And in the process of movement does not flicker and does not go out.
That's all !