An SCR Based Burglar Alarm - Adding Extra Zones

Posted on Feb 4, 2014

You can add as many extra zones as you like to the SCR Burglar Alarm System. The first circuit is designed to be used with the usual types of normally-closed input devices such as - magnetic-reed contacts - micro switches - foil tape - and PIRs. The second circuit has an additional normally-open trigger for use with devices such as pressure mats.

An SCR Based Burglar Alarm - Adding Extra Zones
Click here to download the full size of the above Circuit.

The Green LEDs are there to tell you that the various trigger circuits are intact. They should all be lighting - before you set the alarm. Otherwise - the Siren will sound the instant you operate the control switch. This module has four separate zones. Each can be triggered by normally-closed devices such as - magnetic-reed contacts - passive infra-red detectors - foil tape etc. Zone 4 has an additional input for normally-open devices such as pressure-mats.

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