TEMPERATURE SENSOR USING TWO TRANSISTOR

Temperature Sensor Using 2 Transistors

This is a simple circuit developed by me to sense the temperature. The
TERMISTOR used in this circuit is used as the temperature sensor. The
resistivity of the thermistor varies with increase/decrease in
temperature. This circuit is as same as the dark/light sensor. The
difference is, in the place of the LDR(light dependent resistor) i
placed a thermistor.

The components used are given below.......

Q1 = BC108 or BC548 or BC547

Q2 = BC108 or BC548 or BC547

R1 = 10k

R2 = 27k

B1 = 9v

LED

NoTe:
Adjust the value of R1 and R2 to get much brightness from LED.
You can also use a buzzer or a normal bulb instead of the LED........ :)