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.
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Step 1: Components Required -
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.