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Hand Cranked Flashlight

by Ron Kurtus (28 January 2016)

A hand cranked flashlight is a useful type of flashlight that can be used without worrying that the batteries are still good. This electric machine uses muscle power to turn an electric generator and create the current needed to light the bulbs.

The parts of the hand cranked flashlight are the crank, gears, electric generator, electronics, battery, and light-emitting diodes (LEDs).

Cranking the handle rotates the gears inside the flashlight, which then turn the generator rotor. This charges the battery and provides electricity to light the LEDs.

Questions you may have include:

This lesson will answer those questions.



Electric machine

A hand cranked flashlight turns muscle power into electrical power and then visible light. The crank turns gears that create a speed mechanical advantage and turn the generator at a fast rate.

The rotors of the generator convert motion into electrical energy that then charges a battery. The current then goes to the LEDs to create visible light.

Full view of flashlight

A hand cranked flashlight has a crank on its back side that folds up. There is a button switch on the top of the flashlight.

Hand cranked flashlight

Flashlight

The flashlight has a crank on its back side that you can turn to generate the electricity required to charge the battery and light the bulbs, which are light-emitting diode (LED) bulbs. LED bulbs require much less electricity than standard bulbs, and they put out more light.

Hand cranked flashlight - Crank handle

Flashlight crank handle

Inside of flashlight

Taking the flashlight apart allows you to see its parts.

Crank assembly removed

First, the crank assembly is removed, allowing you to see the inside electronics.

Hand cranked flashlight - Crank assembly removed

Crank assembly removed

Gears turn generator

You can take the electronics board out to view the gears. The crank turns one set of gears that increase the speed of the final gear that is attached to the generator.

Hand cranked flashlight - Flashlight disassembled to show gears

Flashlight disassembled to show gears

Generator charges battery

The generator is made of permanent magnets and a wire rotor. It both charges the battery and lights the LEDs. With a charged battery, you do not need to turn the crank.

Hand cranked flashlight - Generator charges the battery

Generator charges the battery

Summary

The hand cranked flashlight is an electric machine that uses muscle power to turn an electric generator and create the current needed to light the LED bulbs.

Cranking the handle rotates the gears inside the flashlight, which then turn the generator rotor. This charges the battery and provides electricity to light the LEDs.


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Resources and references

Ron Kurtus' Credentials

Websites

Mechanically powered flashlight - Wikipedia

Electrical machine - Wikipedia

Electric machine - Wikipedia

Electromechanics - Wikipedia

Machines Resources

Books

Top-rated books on Simple Machines

Top-rated books on Machines


Questions and comments

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