Temp sensor to turn on relay to fan

[stuee]

Im installing a thermo fan in my car but want to use the existing temp sensor to my temp gauge for the sensor. I can find out the resistance for it but something i can vary too would be good.
If anyone knows a simple circuit / diagram i would appreciate it.

thanks

 

[Hero999]

A simple comparator circuit will do, I'd recommend the LM311, read the following :

http://home.cogeco.ca/~rpaisley4/Comparators.html
http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=17