Dynamo Flashlight Torch

Mechanically powered flashlight

Dyno torch

Interior of a 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 or light-emitting diodode. 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 II[citation needed] 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.[citation needed] 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.

Shake type design

The linear induction or "shake flashlight" is another design of a mechanically-powered flashlight. It was sold via direct marketing campaigns beginning in 2002.

This design contains a linear electrical generator which charges a capacitor when the flashlight is shaken lengthwise. The battery or capacitor powers a high-intensity white LED array. 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.

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. The capacitor is used instead of a rechargeable battery since it doesn't wear out like a battery.

Other functions

A crank-charged flashlight with built-in AM/FM radio.

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.

See also

Self-powered equipment

External links

ElectronicCrafts.org: Homemade shakelight

Instructables: A homemade solenoid type dyno torch inside a TicTac box.

Die Goldcap-Dynamolampe (in German) converting a dyno torch to LED operation with capacitor storage

Categories: FlashlightHidden categories: All articles with unsourced statements | Articles with unsourced statements from February 2007 | Articles with unsourced statements from June 2009
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