Sunday, 21 December 2014

“temperature dependent fan Speed control”

Hello, how are you?
Thank you for coming again on
Today I am going to discuss on a very simple but effective and interesting project, that is “temperature dependent  fan Speed control”
Hope you all experienced the fact that, during the end of the summer season, the temperature of the environment   falls significantly, at late of night. Sometimes that becomes the cause of getting cold, if the fan is running still then.
How it would be, if the fan speed decreases with the decrease of temperature?
Yes, in this project we are going to do that…………………
Components required- 1. Any npn transistor
                                            2.temperature sensor ic LM35
3.A SIMPLE 3 VOLT DE MOTOR(you               can find it inside a toy car)
                                            4.  A 5 volt dc source

Circuit diagram- here is a very simple circuit diagram for you
HOW IT WORKS- it’s working principle based on the amplification characteristics of a transistor, a small change in base current causes a greater change in collector current,
The temperature sensor ic LM 35 gives a output ,due to the change of temperature of environment, this pulse is fed to the base of the transistor. And the output collector current runs the motor.

Special note-1. here I have  used simple 3 volt dc motor, if you want to drive a bigger one you must have to interface a relay with the circuit.
 2.the circuit needs some modification, to drive house hold single phase fans,
In my next post I will discuss about the modification.
3.if you want to control the sensitivity of the circuit, you may use a variable resistance between sensor output and transistor base.
Thank you for reading,