Fire Alarm Using 555 Timer - Dewashish Singh RA2111003010213

Here the 555 timer IC has been configured in Astable mode so that the Alarm (Buzzer) can produce an oscillating sound. In Astable mode, capacitor C charges through resistance R1 and R2, till 2/3 Vcc, and discharges through R2 till it reaches to 1/3Vcc. During the charging time, OUT PIN 3 of 555 IC remains HIGH and during discharging it remains LOW, that's how it oscillates. We have connected a Buzzer to OUT pin, so that it produce beep sound, when 555 is high. We can control the oscillation frequency of the alarm by adjusting the value of R2 and/or capacitor C.