Circuit of fire alarm detection

The rooms are vulnerable to fire as a storage material, flammable, requires a system to prevent the occurrence of a fire. For example, using a fire alarm detection, so for example occur if a flame that can quickly and others that are easily fire did not cause a fire is greater.

Here is a simple alarm circuit is based on the LDR and the lamp of a pair of smoke alarm sensors fire.The sensor works produced fire.The circuit produces an alarm when a fire smoke.

 

Fire alarm detector Components :

• The speaker can be 8Ω tweeter.

• POT R4 can be used to adjust the sensitivity of the alarm.

• POT R3 can be used to vary the volume of the alarm.

• Any general purpose NPN transistor (BC548, BC148, 2N222) can be used for Q1.

• The circuit can be powered by a 9V battery or 9V DC power supply.

• On the contrary, it is bright LED bulb 1K resistor in series on it.

Where there is smoke from the bulb will drop directly LDR.The LDR resistance is low and hence the voltage across its terminals (less than 0.6 V). The transistor is blocked and no happens.When there is enough smoke to obscure the light falls on the LDR, LDR resistance increases and the fact that the voltage across the transistor passes it.Now ON.This feeds IC1 and the output 5V.This power tone generator IC UM66 (IC2) to play music for music will be amplified by IC3 (AD 2002) to drive the speaker.

The diode D1 and D2 in combination drops to 1.4 V for the nominal voltage (3.5 V) to the UM66. UM 66 can not support more than 4V.