Please help - Automatic fan controler

[badcompany2all]

Hi


I want to use this circuit as my amp's Automatic fan controller but I have a little problem with it :
When the sensor diodes get a little warm (But not too much) the fans want to run but because of the low voltage in output of transistor (around 5 or 6 V) they can't and this condition make the transistor warm and I want to do something about it
I used a Relay at the output of the transistor and connect the fans directly to the 12VDC (regulated) but I pass the positive wire of the fans from the NO(normally open) contact of the relay so if the relay turns on than the fans could runs with 12VDC.
It was pretty good but when the temperature of the Sensor diodes is low, the relay keeps turning on and off and in this way the relay will not work for a month


I want to do something that when the output of the transistor became around the 8 or 9V than the fans can run and below this voltage they doesn't have any voltage at all to try to run


Could you give me an idea to how to do this ??

thank you

[jackand08]

Just a quick tip, it's not a good idea to re-post exactly the same question in different forums as it wastes space and is quite a good way to get yourself banned from the forum.

Choose the right section of the forum first and then post ONCE in that section.