With just four components, you can assemble an efficient anti-theft system for your home. Opening doors, windows, trap doors or even removing objects from certain places can trigger a buzzer. The system is simple to install and, depending on the strength of the buzzer, will make a lot of noise when triggered.
The sensors are very thin pieces of wire which enclose doors and windows. When interrupted, they cause the SCR to trigger. Of course there should be a hidden plug to disable the alarm. All components used are common. In Figure 1, we have the complete diagram of the alarm.
In Figure 2, we show the device of the assembly, with smaller components installed on a terminal strip.
In Figure 3, we show how to place the sensors in a door and in a window. Of course, the number of sensors is unlimited.
In the standby condition, the alarm consumption is extremely low, which allows it to be permanently connected. Consumption depends on R1.
Material list
TIC106B (110 V) or TIC106D (220 V) - silicon controlled diode
D1- 1N4004 - silicon diode
R1- 100k ohms at 470k ohms x 1/8 W - resistor - brown, black, yellow or yellow, violet, yellow
X1, X2, etc. - sensors
Miscellaneous: power cable, 110 V or 220 V buzzer, wires, bridge, welding, etc.
