BICYCLE GENERATOR

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I recently bought a bike to drive to work, and indeed, to ride and enjoy cycling. For safety, I turn on the front and rear lights so that road users notice me better. My LED lights are powered by two AA batteries. And the charge lasts only 4 hours. Actually, this prompted me to think about purchasing a bicycle generator that could power all the lights.
I did not find anything in the stores. All lights offer battery power. Then I decided to make a generator for the bike myself, from the fact that it comes to hand, so to speak ...

And then I remembered that I was somehow making a generator from a stepper motor. I decided to repeat the idea. But where to get a stepper motor? They are almost in all office equipment. I climbed into the pantry and found an old printer there. Naturally there was a pair of stepper motor in it. I took one, I don’t need anymore.

What else do you need for a generator?

You will need a few things if you want to build a generator for a bicycle. Here is what they are:

- Stepper motor from a printer or other equipment.
- 8 pieces of diodes, any, per current 0.5 - aliexpress
- LM317 voltage regulator - aliexpress
- Radiator for LM317 - aliexpress
- Development board - aliexpress
- Switch - aliexpress
- Housing for regulator - aliexpress
- Wires.
- Mount from the wing.
- A wheel from the machine.

Regulator circuit with rectifier

We need to assemble a voltage regulator so that it not only rectifies the current from the stepper motor, but also regulates the output voltage, thereby protecting the LEDs from power surges when driving. The controller circuit is simple. Rectifier bridge on diodes and voltage regulator on the LM317 chip.

I put it all together on a breadboard with holes. I simply inserted the parts, bent the contacts in the direction of soldering, and soldered everything. Soldered the wires and now my regulator-rectifier is ready.

The tumbler can turn off the generator.

Generator assembly

We assemble the mount of the stepper motor to the wheel. The principle is simple: the wheel rotates a stepper motor, the engine generates electricity.
I have been thinking for a long time how to realize the fastening both simpler and more reliable. Here is what I came up with:
I took the mount from the wing (boot, mudguard). An aluminum corner was screwed to it, cutting it a bit. And already attached to the corner stepper motor. Everything - the design is checked, it works fine. Of course, it is desirable that she spring the engine to the wheel, but in principle, and so it is quite normal.
Oh yes. A wheel is put on a stepper motor from a machine with a rubber tire. An electrical tape is wound around the motor shaft so that the wheel is tightly pulled onto the shaft. Nothing better came to mind.

Regulator mount

I also thought for a long time where to place the regulator case, where to attach it, because it should be in the vicinity of the stepper motor, otherwise you will have to pull 4 wires from the stepper motor.
Finally, I came up with and decided to fix the regulator on the racks on the same bracket where the stepper motor is mounted.
I cut a rectangle from thin aluminum foliage and screwed it with long bolts through 1 cm long racks. Well, I attached a regulator to the rectangle.

Generator Operation Check

The stepper motor that I took was 24 volts. And at normal speed, the bike gave out more than 30 volts. The output regulator produced 3.1 volts. Which is quite normal. If this voltage does not suit you, adjust it with 150 and 220 Ohm resistors. In general, you can solder a variable resistor and adjust the voltage as you wish.
I brought the wires from the regulator to the front light. Connected in parallel with batteries. As a result, when the bike is standing, the flashlight shines from batteries. And when the bike rides, the lamp shines from the generator, and the elements charge a little. Ideally, of course, you need to use batteries, but finger batteries with a voltage of 1.2 volts, the lamp will burn dimly. But in principle, the batteries can be thrown out altogether, and the headlight will burn only in motion. In general, whoever wants to.