Wire Break Alarm with Delay

Description

When the thin-wire loop running across the entrance door is broken, the kit Wire-Break Alarm With Delay activates after a delay of 15 to 30 seconds. The time is set by adjusting the variable resistance. Thus the occupants get sufficient time to lock the room from the outside and catch the thief. The circuit uses CD4060, which is a 14-stage ripple-carry binary counter/divider and oscillator. The Break Alarm Circuit is wired as a timer here and does not need input pulse for the trigger. CD4060 gets activated as soon as the power supply is switched on.

In the Wire Break Alarm Controller, with delay output pin, 3 of CD4060 goes high after the lapse of preset delay set through Variable resistance PR1. Transistor CL100 is wired as a switch to power the timer section built around CD4060. When the wire loop is closed, a transistor does not conduct. So power to the timer circuit is not available and the piezo buzzer does not sound. On the other hand, when the wire loop is broken by some intruder, transistor CL100 conducts to power the circuit, and the piezo buzzer sounds after 15 to 30 seconds. CD4060 can be reset by connecting the wire loop or interrupting the supply.