Mechanically powered flashlight

A mechanically powered flashlight is one of several varieties of flashlight that are powered by electricity generated by the muscle power of the user, so they do not need replacement of batteries, or recharging from an electrical source. The light source can be a miniature incandescent bulb or light-emitting diode.

Different methods are used to generate the required power:
*squeezing a handle
*winding a crank
*turning or shaking the device itself

They can also be distinguished by the technique used to store the energy: a flywheel, a battery or a capacitor.

Dyno torch

A dyno torch is a flashlight or pocket torch which stores energy in a flywheel. The user repeatedly squeezes a handle to spin a flywheel attached to a small dynamo, supplying electrical current to an incandescent bulb. Because electrical power is only produced when the handle is squeezed, a switch is not needed. The flywheel makes sure the light is fairly constant, despite the fact that the power supply (the squeezing) is intermittent. Dyno torches were very popular in Europe during World War IIFact|date=February 2007 because the electrical power supply to homes was not very reliable.

In an alternative design, the dynamo charges a rechargeable battery or a capacitor, and may offer 15 minutes or more of illumination for 1 minute of charging. This version could be considered less reliable for emergency use because the battery will eventually fail and need replacement.

Dyno torch design

In the photo, the L-shaped handle has a gear rack, which spins the white step-up gear, which in turn spins the flywheel on which is mounted the dark grey magnet, seen on the left. The magnet induces an electrical current in the red copper winding, seen on the right. The current from the copper winding flows through the incandescent bulb filament (not shown). A spring and ratchet returns the handle to its original position after each squeeze.

Faraday flashlight

The Faraday flashlight is another design of a mechanically-powered flashlight sold via direct marketing campaigns beginning in 2002.

The Faraday flashlight contains a linear electrical generator, which charges a super capacitor when the flashlight is shaken lengthwise. The capacitor powers a high-intensity white LED array. Simply shaking the light for about thirty seconds provides about five minutes of light. Shaking the unit for 10 to 15 seconds every 2 or 3 minutes as necessary permits the device to be used continuously. This particular design of flashlight is documented in Cite patent|US|6729744 and Cite patent|EP|1413037. The super capacitor is used instead of a rechargeable battery since it doesn't wear out like a battery.

In the linear generator, a sliding rare earth magnet moves back and forth through a solenoid, a spool of copper wire. A current is induced in the loops of wire by Faraday's law of induction each time the magnet slides through, which is used to charge the capacitor. This type of generator was first invented by Michael Faraday, so the flashlight was named for him.

Other functions

Some mechanically powered flashlights include other functions and features beyond just a source of light. For example, certain models may have additional special operating modes, such as flashing red or yellow lights that can serve as a caution or warning to other people that might see the light. Some models include a loud electronic siren that can also help warn of danger, or assist in locating someone who is lost. There are also many models of mechanically powered flashlights that include a built-in AM/FM, weather or shortwave radio.

ee also

*Self-powered equipment

External links

* [http://www.instructables.com/id/E5BLCRZ178ES9J6A88/ Instructables] : A homemade solenoid type dyno torch inside a TicTac box.
* [http://www.b-kainka.de/bastel48.htm Die Goldcap-Dynamolampe] (in German) — converting a dyno torch to LED operation with capacitor storage
* [http://www.asotv.info/Categories/catElectronics/Faraday_Flashlight.aspx ] To see a 3rd party Video review of a Faraday Flashlight by ASOTVI www.asotv.info