Laser Beam Light Activated Remote Control Circuit

Posted on Feb 6, 2014

The following post illustrates a simple light toggled/operated remote control circuit, which can be activated by an ordinary flashlight or more effectively through a laser beam unit (key chain type). The LDR is connected across the base of thetransistor and the positive supply such that when light falls over the LDR, T1 receives the required base

Laser Beam Light Activated Remote Control Circuit
Click here to download the full size of the above Circuit.

bias and conducts. When T1 conducts, the high potential at pin 14 of IC1 is pulled to logic low. However since a logic low wouldnt effect pin#14, IC1 does not respond as yet. The moment light on the LDR is switched OFF, T1 is switched OFF and pin#14 now instantly receives a subsequent logic high via R5. now IC1 responds, and shifts its output from pin#3 to pin#2. This makes pin#3 logic low, activating T2, and the preceding relay driver stage.

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