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Component Introduction
IR RECEIVER SENSOR:
IR detectors are little microchips with a photocell that are tuned to listen to infrared light.
They are almost always used for remote control detection - every TV and DVD player has
one of these in the front to listen for the IR signal from the clicker. Inside the remote control is
a matching IR LED, which emits IR pulses to tell the TV to turn on, off or change channels. IR
light is not visible to the human eye, which means it takes a little more work to test a setup.
There are a few difference between these and say a CdS Photocells:
IR detectors are specially filtered for Infrared light, they are not good at detecting visible
light. On the other hand, photocells are good at detecting yellow/green visible light, not
good at IR light
IR detectors have a demodulator inside that looks for modulated IR at 38 KHz. Just
shining an IR LED won't be detected, it has to be PWM blinking at 38KHz. Photocells do
not have any sort of demodulator and can detect any frequency (including DC) within
the response speed of the photocell (which is about 1KHz)
IR detectors are digital out - either they detect 38KHz IR signal and output low (0V) or
they do not detect any and output high (5V). Photocells act like resistors, the resistance
changes depending on how much light they are exposed to.
What You Can Measure
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