Mains Supply Failure Alarm

When ever AC mains deliver fails, this mains supply failure alarm circuit indicators you by means of sounding an alarm. It additionally gives a backup mild to help you find your way to the torch or the generator key within the dark.
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Mains Supply Failure Alarm Circuit
The circuit is powered directly by means of a 9V PP3/6F22 compact battery. Pressing of transfer S1 provides the 9V electricity supply to the circuit. A red LED (LED2), together with zener diode ZD1 (6V), is used to suggest the battery power stage. Resistor R9 limits the running modern (and subsequently the brightness) of LED2.

When the battery voltage is 9V, LED2 glows with complete depth. As the battery voltage goes underneath 8V, the depth of LED2 decreases and it glows very dimly. LED2 is going off whilst the battery voltage is going underneath 7.5V.

Initially, in standby country, both the LEDs are off and the buzzer does not sound. The 230V AC mains is at once fed to mains-voltage detection optocoupler IC MCT2E (IC1) through resistors R1, R2 and R3, bridge rectifier BR1 and capacitor C1. Illumination of the LED inner optocoupler IC1 activates its internal phototransistor and clock enter pin 12 of IC2 (related to 9V thru N/C contact of relay RL1) is pulled low. Note that best one monostable ofdual-monostable multivibrator IC CD4538 (IC2) is used right here.