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DiscoverCircuits.com, has
26,000+ electronic circuits or schematics
cross-referenced into 500+ categories. As a
vital resource for engineers, hobbyists, inventors &
consultants, the site's collection of information will
help you find quick solutions to electronic design
problems. |
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DiscoverCircuits.com
-- Hobby Corner
Last Updated on:
03/19/2008 06:54:11 AM |
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Shake to Charge Flashlight -- Page 1 of 4
designed by David A. Johnson, P.E. |
| Have you ever wondered how some of those “Forever” flashlights work? These devices appeared several years ago and are
often sold on some TV home shopping networks. A company in Colorado (Applied Innovative Technologies www.appliedinnotech.com) made the original device but knock-offs from China are now
popping up everywhere. That fact that some of those devices don’t even work will be a topic for later discussions. |
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Shake & Charge Flashlight
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| I bought one of the cheaper counterfeit devices and took it apart. There were no manufacture or country of origin
markings anywhere on the device. I traced out the circuit. It is not much more than a coil of wire, a magnet, a bridge rectifier, super capacitor and white LED. A small magnet
attached to an on/off switch is used to turn on the light by activating an internal reed relay. This method maintains a tight weatherproof seal and is about the only thing I found cleaver
about the device. Shaking the thing forces a large magnet slug to slide back and forth inside the body of the device. Two rubber stoppers cushion the magnet at each end. In some other more
expensive shake to charge flashlights, they use two more magnets as
contact-less bumpers. |
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