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| Temperature Sensor Using Single Transistor |
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.......
Q = BC108 or BC548 or BC547
R1 = 10k
R2 = 27k
B = 9v
LED
NoTe:
Adjust the value of R1 and R2 to get much brightness from LED............
You can also use a Buzzer or an ordinary Bulb instead of LED............. :)
hi. can i ask u something? can you briefly explain how the circuit function??
ReplyDeletehi meerah.... this circuit is a common emitter voltage divider circuit. basically in a circuit the current flows trough low resistance. in this circuit when the resistance of the thermistor is high with respect to R2 the current flows through C-E configuration and the led gets illuminated. when the resistance of the thermistor is too low with respect to R2, the current flows through B-E configuration an the led remains in off state. here the transistor acts as a switching device. if u want to know about this circuit deeply, then just get through the voltage divider circuits. still you have any doubts about this, you can ask me.
ReplyDeleteThank you......
Thanks.. if i have any prob,i will ask u again. :)
ReplyDeletecan I replace the LED with a buzzer?
ReplyDeleteYes you can..... :)
Delete