•  
  •  

Power supply failure alarm

Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable duration when the supply fails.
This circuit can be used as an alarm for power supplies in the range of 5V to 15V.
To calibrate the circuit, first connect the power supply (5 to 15V) then vary the potentiometer VR1 until the buzzer goes from on to off.

Whenever the supply fails, resistor R2 pulls the base of transistor low and saturates it, turning the buzzer ON.

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like


Nu-Coil Concentrated Air Conditioner Coil Cleaner - 1 gallon (128 oz.) picture

Nu-Coil Concentrated Air Conditioner Coil Cleaner - 1 gallon (128 oz.)

$29.00



Coil for Maytag Model 72 D-DA Ignition NEW Multi Motor Gas Engine  picture

Coil for Maytag Model 72 D-DA Ignition NEW Multi Motor Gas Engine

$129.95



Deep Ground Metal Detector Gold Finder LCD Display w/ Waterproof Search Coil-NEW picture

Deep Ground Metal Detector Gold Finder LCD Display w/ Waterproof Search Coil-NEW

$117.99



HELI-COIL Helicoil THREAD REPAIR KIT 1/4-20 X .375 picture

HELI-COIL Helicoil THREAD REPAIR KIT 1/4-20 X .375

$15.75



Garrett ACE 300 Metal Detector Waterproof Coil, Headphones & Free Accessories picture

Garrett ACE 300 Metal Detector Waterproof Coil, Headphones & Free Accessories

$254.95