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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, November 29, 2011 08:14 PM
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Cheap Light Power Meter Circuit
designed by David Johnson, P.E. |
| Some time ago I was
experimenting with the use of some low leakage photovoltaic solar cells, to
harvest some energy from the diffuse lighting inside a room. The plan was to
use a small array of solar cells (the type often used on solar powered
calculators) to keep a super capacitor charged, drawing power from the light
within an inside room. |
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Our human eyes are a poor gage of the intensity of
the light within a room, so a more accurate instrument was needed to determine how
much power was available. I blew the dust off an old 1-milliamp meter and
attached a one centimeter square PIN photodiode to it. This allowed me to
quickly measure how much current a solar cell array could generate anywhere there
was light. I was surprised by just how much useful power there was,
especially when a room was brightly illuminated by sunlight reflecting off walls
and ceilings. Often, the current exceeded 200 microamps per square
centimeter. Of course in direct sunlight, the current exceeded 8 milliamps for a
1cm x 1cm solar cell. |
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eMail David A.
Johnson, P.E. about this circuit |
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