This is how to make a generator out of your bike in a few easy steps. What I like about this project is that you dont have to take the chain off your bike or permanantly change your bike, like other bike generators. You can use this to charge your phone, batteries, etc. You don't need advanced skills to make it, it can be built by almost anyone.

Supplies

1. This is the stepper motor I used:

https://amzn.to/2IeOoJb

2. Capacitors I used:

https://amzn.to/3iNtDRx

3. Full Bridge rectifiers I used:

https://amzn.to/3nGLKMv

4. A few standard 2x4's

5. A drill bit the same size as the pegs on your bike (1 and 1/4 in for mine)

Step 1: Building the Circut

Here is a link to the video of me building and testing the generator, I was able to use it to charge an old phone I had. For testing I used a 10w power resistor.

The circut is a pretty simple AC to DC converter.

For this I used a Fuuuullllllll Bridge Rectifierrrrr! (ElectroBOOM reference) and a capacitor.

I wired one pole of the stepper into the AC inputs of the full bridge rectifier, then wired the + and - to a wire with a capacitor in parallel (minding polarity) to convert the AC to DC. See the video for more info.

For the roller that I 3d printed check the video description for the link.

Step 2: Building the Supports

To hold the back of the bike of the ground I used some 2x4's an a 1 and a 1/4 in drill bit, This was the perfect size for the pegs on my bike but yours might be different. For screws I just used standard deck screws. When it was done it looked like an upside-down T. I put a support on each side and ended up putting a bar across the sides for stability. For the stepper motor I built a box to hold it in place, depending on which motor you get the box will need to be a different size, but just make sure you have room on top of the 2x4 to put the box with the motor so it's touching the wheel.

Step 3: Final Assembly

I screwed the motor box to the 2x4 then put the motor in it and screwed the top on. Tou need a top on the motor box or it will not have enough pressure on the wheel to spin with out slipping. Before I put the motor in I deflated the tire a significant bit , put the motor on then the top for the motor box, then reinflated it a little. I have found this is the best way to make sure you have enough pressure on the wheel to prevent the roller slipping.