Posted on Apr 27, 2012

This simple IR detector turns on a real LED when Q2 is exposed to invisible IR radiation found in fiber-optics systems, position sensors, and TV remote-control units. The device can be built on top of a 9V battery and held in place with RTV. Its power dissipation is virtually zero, unless IR radiation or high ambient light is present. Normal fluorescent lighting is not a problem, but if necessary add an IR filter to the Q2 detector to exclude ambient light.

Click here to download the full size of the above Circuit.

Exposing the detector to a strong light or IR source gives a quick check of the battery and the red LED.

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