Handheld Generator Using DC Gear Motor

This is a handheld generator that I made using a DC gear motor. When the crank is rotated, the motor shaft rotates and the led bulb attached to the motor glows.

Supplies

Gear motor with wheel (Easily available in electronics or hobby shop)
Any small LED

Making the Generator

It's very simple to build the generator. Connect an LED with the motor terminals using wires. It doesn't matter how you connect the LED. Make a handle for the generator, I used a piece of 1 inch diameter PVC pipe.

Making the Crank

Take the wheel and remove the rubber tire. Then, glue a handle in one of the holes as in the diagram. Attach the wheel to the motor shaft. You are finally done.

If the LED doesn't glow, rotate the crank backward or connect the LED opposite.

Science Behind the Generator

A motor is basically a coil in a magnetic field. When electricity is supplied, flux is created as per Faraday's Law and the coil rotates. A generator is basically the opposite of motor. When the shaft is rotated, the coil rotates in the magnetic field and induces an emf. This induced current can be used to drive a load ( an LED in our case).

The gears of the motor help to convert torque into speed, Even if you rotate the gear box shaft slowly, the gearbox increases the speed and the motor shaft rotates at a higher speed which in turn provides enough current to consistently power the LED.