Monday, March 26, 2012 by skemarangkaian
|Power supply failure indicator circuits|
Whenever the supply fails, resistor R1 pulls the base of transistor low and saturates it, turning the buzzer ON.
- This circuit can be used as an alarm for power supplies in the range of 5V to 15V.
- The piezo buzzer needs to be an active type (not a piezo diaphragm).
- The purpose of the diode is to prevent the charge on the electrolytic being passed to any other part of the circuit when the power fails.