Very Sensitive Fire Alarm Circuit Using Relay

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Hii friend,

Today I am going to make a circuit of Fire Alarm which is very sensitive.Today I will make this circuit using Relay and Transistor BC547.

Let's get started,

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Step 1: Components Required -

(1.) Photodiode x1

(2.) Buzzer x1

(3.) Relay - 6V x1

(4.) Transistor - BC547 x1

(5.) Battery clipper x2

(6.) Battery - 9V x2

Step 2: Transistor - BC547

This is the pins of this transistor.

C - Collector,

B - Base and

E - Emmiter.

Step 3: Connect Transistor to Relay

Firstly we have to connect transistor to the relay.

Solder Collector pin of transistor to coil-1 pin of the Relay as you can see in the picture.

Step 4: Connect Photodiode

Next we have to connect Photodiode to the relay.

Solder Cathode leg of Photodiode to Coil-2 pin of Relay and

Anode leg of Photodiode to Base pin of the Relay as solder in the picture.

Step 5: Connect Battery Clipper Wire

Next solder +ve wire of battery clipper to Coil-2 of Relay and

Solder -ve wire of battery clipper to emmiter pin of the transistor as you can see in the picture.

Step 6: Next Connect Buzzer

Solder -ve pin of buzzer to common pin of the Relay.

Step 7: Connect Second Battery Clipper

Now we have to connect second battery clipper wire to the circuit.

Solder +ve wire of battery clipper to +ve pin of buzzer and

solder -ve wire of battery clipper to NO (Normally Open) pin of the Relay as you can see in the picture.

Step 8: Connect Batteries to Battery Clipper

Step 9: How It Works

When fire will burn around this circuit with distance approx 5Cm then Buzzer will give sound automatically.

NOTE : We can also connect 3V LED to this circuit.Connect 3V LED with 220 ohm resistor in the parallel of Buzzer.

Thank you

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