From: David J. Romano (romano@agfa.com)
Date: 02/02/00-07:46:15 AM Z
Building an IR meter is quite simple.
The parts are:
Radio shack project case
Radio shack needle indicator voltmeter
Photoconductive cell, Cds or Si
Radio shck temporary on/off push button switch
Battery, 1.5V, 3V or 9V
The wiring is simple. The battery is located between the push button switch and
the voltmeter along one set of wires (black). The photocell is located between
the push button switch and the voltmeter along the other set of wires (red). The
photoconductive cell will become more conductive in the presence of light,
thereby allowing more current to reach the meter. That's the premise of the
meter. Filter the light with an IR filter and you've got an IR meter. Changing
the voltage of the battery will adjust the sensitivity of the meter.
Alternatively, a potentiometer ( a variable resistor, or "dimmer") could be
used. The photoconductive cell can be Cadmium sulfide of Silicon. The wiring
described would be for the CdS. Go to the Hamamatsu website at
www.hamamatsu.com. Look up the photocell and request a sample. You should get it
for free. If not, they are inexpensive anyway.
Contact me offline if you have any questions
Dave
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