Simple Fire Alarm Circuit

The post discusses a simple fire alarm circuit that you can build and install at home or shop. At the point when there is a fire breakout in the room the temperature increments.

This ultra smaller and minimal effort blaze alert faculties fire breakout in light of this.

Transistor BC177 (Q1) is utilized as the fire blaze sensor here. At the point when the temperature expands the leakage voltage of this transistor likewise increments.

The circuit is planned so that when there is an increment in the above leakage of Q1, transistor Q2 will get one-sided.

Therefore when there is a flame breakout the transistor Q2 will be on. The emitter of Q2 (BC 108) is associated with the base of Q3(AC 128).

So when Q2 is ON Q3 will be likewise ON. The transistor Q3 drives the hand-off which is utilized to drive the load ie,light, bell, horn and so forth as an evidence of the fire.

The diode D1 is utilized as a free wheeling diode to shield it from back EMF created when hand-off is exchanged.

Notes for the above Simple Fire Alarm Circuit

The Preset R1 can be utilized to any wanted temperature level for setting the alert ON.

This is not a lock type alarm, that is; when the temperature in the
region of the sensor diminishes beneath the set point the caution stops.

The circuit can be fueled utilizing  a 9V battery or a 9V battery eliminator.

All capacitors are electrolytic and must be evaluated no less than 10V.

The load can be associated through the C,NC,NO purposes of the relay contacts as per your need.

The adjustment could be possible utilizing a solder iron, and a
thermometer. Switch ON the power supply. Keep the tip of patching iron
close to the Q1. Same time additionally keep the thermometer near to it.
At the point when the temperature achieves your coveted quality seal
R1.