Simple Alarm Circuit Diagram. The contact is normally closed. Circuit diagram of the sound alarm unit 1 as shown in the circuit diagram the main components of the alarm unit are two 555 timers a bipolar junction transistor bjt and a loudspeaker.
The easiest way to do this is run a current through a thin line of foil wire affixed to the surface of the glass. The circuit can be used as a laser door alarm laser motion detector laser proximity sensor or detector trip wire alarm and for other simple home security purposes. Intruder alarm using an ordinary conductor as the sensor.
We identified it from well behaved source.
This is a simple alarm circuit. Nmotion mach3 usb cnc controller. Simple motion sensor alarm light. With the scr switched on a route to ground is supplied by means of bz1 a 6 to 12 volt bell and scr1 resulting in bz1 to sound the alarm.