•  
  •  

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

Epro 142AX Advanced Memory Test System with All Cards / Boards
$463.0 Epro 142AX Advanced Memory Test System with All Cards / Boards picture
FANUC A20B-3900-0160/04A MEMORY CARD * NEW NO BOX *
$596.0 FANUC A20B-3900-0160/04A MEMORY CARD * NEW NO BOX * picture
Used Toshiba ACTU3A V.2 Control Processor Board w/512mb SD Memory Card
$79.0 Used Toshiba ACTU3A V.2 Control Processor Board w/512mb SD Memory Card picture
Calculator CH-3181A 8 Digits Percentage Memory Display School Office moc
$2.73 Calculator CH-3181A 8 Digits Percentage Memory Display School Office moc picture
Smith Corona Memory Correct Correcting Cassette Typewriter in box with manual
$39.0 Smith Corona Memory Correct Correcting Cassette Typewriter in box with manual picture