The modular burglar alarm circuit is a features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected permanently to the 12-volt supply, and its operation is “enabled” by opening SW1. By using the expansion modules, you can add as many zones as you require; some or all of which may be the inertia (shock) sensor type. All the green LEDs should be lighting before you open SW1. You then have up to about a minute to leave the building. As you do so, the Buzzer will sound. It should stop looking when you shut the door behind you. They indicate that the Exit/Entry loop has been a successfully restored within the time allowed. When you re-enter the building, you have up to about a minute to move SW1 to the off position. If SW1 is not switched off in time, the relay will energise and sound the main bell. It will ring for up to about 40 minutes. But it can be turned off at any time by SW1.However, it’s much easier to find a fault when the alarm divided into zones, and the control panel can remember which zone has caused the activation. The schematic drawing is like circuit below :
The expansion modules are designed to do this. Although they will work with the existing instant zone, they are intended to replace it. When an area is activated, its red LED will light and remain lit until the reset button pressed. All the modules can share a single reset button.