Two-Zone Burglar Alarm


Posted on Feb 6, 2014

This is a two-zone alarm - with automatic exit, entry and siren cut-off timers. It can be triggered by the usual types of normally-closed input devices - such as magnetic reed contacts - foil tape - PIRs etc. I`ve used a 12-volt supply in the diagram - but the circuit will work at anything from 9 to 15-volts. All you need do is select a siren, buz


Two-Zone Burglar Alarm
Click here to download the full size of the above Circuit.

zer and relay to suit the voltage you want to use. When you move Sw1 to the Set position - you have about 30 seconds to leave the building. If you re-enter through the Exit/Entry zone - the buzzer will sound - and you`ll have about 30 seconds to switch the alarm off. The Instant zone has no entry delay. Anyone entering through the Instant zone - will sound the siren immediately. About ten minutes after the normally-closed loops have been restored - the siren will switch off - and the alarm will return to standby mode. It can then be re-activated by a subsequent intruder. If you don`t want the siren to sound a second time - add the One-Time-Only Module. It forces the siren to switch off after the first ten minutes. And it prevents the alarm from activating a second time. This module has other uses - so it`s worth a look. The various timing components are listed in the diagram. If you want to change the length of any of the delays - change the value of the capacitor and/or the resistor shown. Increasing the value of either - will increases the delay. And reducing the value of either - will shorten the delay.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Loudspeaker Box Amplifier schematic
    1-Ma Current Sink
    Soil Heater For Plants Circuit
    de amst wiskar: robot line folower
    usb-voltage-converter-5v-to-12v.html
    Timer Blox
    Wireless Electronics for Communication
    ISL6405 Dual Output LNB Supply and Control Voltage Regulator with I
    High Power Solid State Amplifier



    Top