•  
  •  

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

Pro Dentist Dental Crystal Base Hard Plastic Teeth Tooth Molar Separable Model
$5.97 Pro Dentist Dental Crystal Base Hard Plastic Teeth Tooth Molar Separable Model picture
Himalayan Salt Lamp - Pink Salt rock lamp Crystal Salt Lamp Brightness Dimmable
$45.27 Himalayan Salt Lamp - Pink Salt rock lamp Crystal Salt Lamp Brightness Dimmable picture
10pcs/set Dental Gems Imitation Crystal Oral Tooth Ornaments Teeth Jewelry 2017
$1.15 10pcs/set Dental Gems Imitation Crystal Oral Tooth Ornaments Teeth Jewelry  2017 picture
FPX115-20 Quartz Crystal Resonator 11.0592MHz 20pF 100Pcs
$35.12 FPX115-20 Quartz Crystal Resonator 11.0592MHz 20pF 100Pcs picture
Powstro Crystal Magic Ball Voice Remote Control Light, RGB LED Stage Light
$27.29 Powstro Crystal Magic Ball Voice Remote Control Light, RGB LED Stage Light picture