urgent help pls! (controlling a fan using LM35 with ADC)

[sherwihn]

can anyone help me..or give any circuit that would trigger a fan using the LM35.

description of what i need: i must maintain a temp inside an incubator from 91-101 degrees fahrenheit...how to turn on a fan if it exceeds or decrees to maintain the temp. inside my incubator...can any1 give me a circuit that will use LM35 with ADC to trigger the fan to ON/OFF without using a microcontroller...PLS i need it urgently...

PS. thnx a lot to who can help me..

 

[Nigel Goodwin]

You just need a comparator or opamp wired as one, it's a really simple and common application - although it usually uses a thermistor, the LM35 should work fine.

 

[sherwihn]

can u give me a circuit digram for it? i need it badly...

 

[Nigel Goodwin]

Check the autofan circuit at

 

[sherwihn]

ah ok..cn i use a LM35 with the circuit?? can u help me or do u have any circuit using only LM35 with ADC to control a fan?

 

[Nigel Goodwin]

ah ok..cn i use a LM35 with the circuit?? can u help me or do u have any circuit using only LM35 with ADC to control a fan?

You could easily modify the circuit to use an LM35 - if you can't manage something as simple as that you don't deserve to pass your course!.