When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very low. Several sensors can be connected in series to protect different places. The sensor can be a read switch or a thin wire that is interrupted when a door or a window is opened. The circuit is shown in Figure. The relay is a sensitive type with a coil depending on the power-supply voltage and current should not exceed 50 mA. Another configuration derived from this is obtained by connecting the output of the second 4093 to the control input of the siren pictured in Figure. This configuration will eliminate the need for a relay.
Alarm
