Audio Alarm Circuit ⁽³⁾

This is a very simple circuit built using only a few components to detect ac mains power failure and its resumption. The heart of the circuit is the most popular timer Ic 555 which is wired as monostable multivibrator. ac power supply failure alarm circuit…

Parts Required Semiconductors: T1 - Transistor BC548 T2 - Transistor BC558 Resistors(all 1/4W, ±5% carbon): R1 - 270 Kilo- ohm R2 - 10 Kilo-ohm Capacitors: C1 - 0.1μF,Ceramic disk Miscellaneous: S1 - SPDT Toggle(On/Off) Switch LS - 8Ohm,1Watt Loudspeaker Battery Holder Printed Circuit Board(PCB) The…

Circuit Diagram Parts Required The circuit shown in the presentation will sound an alarm endlessly until the circuit is switched off. The circuit shown at the top of this page is used to cut off the alarm automatically after a few seconds or minutes. Alarm…