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PHOTOELECTIC
[PE] BEAMS
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Photoelectric Beam Sensors work
similar to a smoke detector except
in reverse, instead of the sensor
waiting for the beam to turn on
to activate the alarm, it waits
for the beam [or light] to be
blocked or interrupted and this
in turn activates the alarm [ie
walking across the beam blocks
the transmission of light causing
an alarm]. |
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These are extremely
reliable and false alarm resistant,
there are many and varied types
on the market. Prices
start at around $350. for a standard
set. There are indoor and outdoor
types as well. |
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