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.
for watch detailed video about Mains Supply Failure Alarm, see below. for getting daily updates follow our facebook page and click see first option in following button. if you interested this. give this post to your friends and relatives.for more videos, subscribe now Hameed Orbit
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.
Circuit operation
When mains is going off, IC2 is precipitated after a brief duration determined by way of additives C1, R4 and C3. Output pin 10 of IC2 goes excessive to ahead bias relay driving force transistor T1 thru resistor R7. Relay RL1 energises to prompt the piezobuzzer via its N/O contact for the time-out duration of the monostable multivibrator (about 17 mins). At the same time, the N/C touch removes the positive deliver to resistor R4. The time-out period of the monostable multivibrator is decided with the aid of R5 and C2.
Simultaneously, output pin 9 of IC2 goes low and pnp transistor T2 receives ahead biased to light up the white LED (LED1). Light furnished via this lower back-up LED is sufficient to search the torch or generator key.
During the mono time-out duration, the circuit may be switched off with the aid of opening transfer S1. The ‘on’ period of the monostable multivibrator may be changed by way of changing the cost of resistor R5 or capacitor C2.
If mains doesn’t resume when the ‘on’ duration of the monostable lapses, the timer is re-prompted after a quick postpone decided through resistor R4 and C3.
