Working of Power Supply Failure Alarm. After soldering the components as per circuit diagram, connect the power supply and turn it on. Then to check the system, turn off the power supply and you will ...

As soon as the mains power fails, the charge stored in the capacitor acts as a power-supply source for transistor T1. Since, in the absence of mains supply, the base of transistor is pulled ‘low’ via ...

Good day My senior colleagues, I designed a circuit to sound an alarm when mains goes off an sound. Good day My senior colleagues, I designed a circuit to sound an alarm when mains goes off an sound ...

Here is a simple power resumption alarm circuit that can be fixed inside the switch box itself. It gives beeps when the power resumes after a power failure. This circuit is ideal to monitor battery ...

Power failure indicator circuit This fuse-cum-power failure indicator comprises an LED (LED1), light-dependent resistor (LDR1), inverter circuit and two timer circuits built around IC NE555. LDR1 and ...

This minuscule power failure alarm circuit is a power supply monitoring device that will set off a piezo-speaker when the ac mains mains supply cuts off. It is very helpful to indicate the loss of ...

The circuit is powered directly by a 9V PP3/6F22 compact battery. Pressing of switch S1 provides the 9V power supply to the circuit. A red LED (LED2), in conjunction with zener diode ZD1 (6V), is used ...