How To Build A Burglar Alarm Using A Cmos 4060

  
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This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-closed input devices - such as magnetic-reed contacts - foil tape - PIRs etc. But it`s easy to add a normally-open trigger. I`ve used a 12-volt supply in the drawing - but the circuit will work at anything from 5 t
How To Build A Burglar Alarm Using A Cmos 4060 - schematic

o 15-volts. All you need do is select a siren, buzzer, and relay to suit the voltage you`re using. When you switch the alarm on - the buzzer will sound eight times. This is the exit delay. Before the end of the eighth beep - you can leave the building without activating the alarm. R6 controls the length and speed of the beeps. It can be adjusted to give an exit delay of anything from about ten seconds - up to about a minute. After the eighth beep - the buzzer should stop sounding. This confirms that the loop has been restored within the time allowed. If the buzzer does not stop - but changes instead to a continuous beep - the loop is open and the building isn`t secure. When this happens - you should switch off the alarm - and check for open doors, windows etc. When you return and open the door - the buzzer will sound again - and the entry delay will start. The entry delay is the same length as the exit delay. But to distinguish it from the exit delay - the buzzer will sound continuously. If the buzzer is sounding continuously - the alarm has been activated - and the entry delay has begun. If you don`t switch the alarm off before the entry delay expires - the siren will sound. The siren will sound only once. Just as R6 sets the lengths of the exit and entry delays - it also sets the siren cut-off time. The siren cut-off delay is 30 times the length of the exit delay. With the exit delay set at 30-seconds - the siren will...



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