Home Alarm Circuit for protecting homes and commercial buildings
This low power circuit is ideal for protecting homes and commercial buildings, as it can be activated by several sensors placed in different locations. The circuit has a bistable behavior as shown in figure 1. Figure 1 - Behavior of the alarm Thus, when any sensor is activated the relay closes its contacts and can be reset by a hidden switch. The system includes the use of NA sensors that can be micro-switches or reed-switches. Assembly We start by giving in figure 2 a small power supply for the circuit. Figure 2 - Power supply for the alarm The transformer has secondary 12 V with current of 250 to 500 mA and the electrolytic is for 25 V. In figure 3 we have the complete diagram of the alarm. Figure 3 - Complete alarm diagram The assembly may be made on the basis of a printed circuit board of the pattern shown in Figure 4. Figure 4 - Printed circuit board for mounting On assembly, observe the position of the integrated circuit an...