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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, June 01, 2021 03:06 PM
Hobby Circuits List
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LINK to Dave's circuit, but DO NOT COPY any files to your WEB
SITE server |
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Shake to Charge Flashlight --
designed
by David A. Johnson, P.E. |
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Reed Relay to turn the
device on & off |
Super Capacitors
used to store energy |
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light from this Reed Relay is weak. It took about a minute of vigorous shaking to
get the first bit of light from it. After a few more minutes of shaking, the
capacitor was fully charged. It might be okay for finding your keys in the dark
but not much more. |
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The complete schematic for this device is shown below.
A few things should be pointed out. First, they use some very cheap 1N4001
diodes in the bridge rectifier circuit instead more efficient Schottky diodes.
They also use a small 0.5 Farad cap with a 5.5 volt rating. I noticed that
that this kind of super capacitor was originally designed
for maintaining data in
memory chips and has a rather high internal equivalent series resistance. This
reduces the overall efficiency, since the device can’t be charged or discharge very
quickly. Some of the power that should go to the LED will end up being
dissipated inside the capacitor. Better super capacitors do exist. |
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Click on Circuit Below to view PDF of Schematic |
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