Dyno torch
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A dyno torch is a pocket torch (or flashlight in AE) without batteries. The user squeezes a handle to operate a small dynamo, supplying electrical current to a miniature incandescent bulb. Dyno torches were very popular in Europe during WWII because the power supply wasn't very reliable.
How it works
In the photo, the L-shaped handle spins a gear, which in turn spins the dark grey magnet mounted on a flywheel, 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). 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.Modern developments
With the advent of white, ultrabright, high-efficiency LEDs, newer versions may use a capacitor to store energy in lieu of the flywheel, making constant actuation of the mechanism unnecessary, and allowing the light to function up to half an hour at a time. Some of these designs use a hand-cranked dynamo. Others use a sliding magnet that is made to move back and forth inside a solenoid by shaking the unit vigorously. While they offer convenience, the capacitor is subject to aging, and so the lamp must be used periodically, at intervals of a few months or less, to slow degradation. For infrequent emergency use, a capacitor-less version is preferred.External links
- [Die Goldcap-Dynamolampe] (in German) — converting a dyno torch to LED operation with capacitor storage
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