Light-Beam Alarm For Intrusion Detection Circuit

Posted on Mar 14, 2013

When the light beam that falls in the CDS photocell is interrupted, transistor (EN3904) conducts thereby triggering SCR1 (CI06) and activating alarm bell. SI resets the SCR. The alarm bell should be a self-interrupting electromechanical type.

Light-Beam Alarm For Intrusion Detection Circuit
Click here to download the full size of the above Circuit.

Lamp should draw at least 100 mA to sensure SCR1 remaining on during alarm cycle

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