looking for temperature PC fan controller with upper, lower limits by R1 R2

[smilem]

Hi, I'm looking for simple temperature control circuit for PC 12V fan, that would control usual 3pin fan. The circuit must have lower

fan start POT R1

and upper

POT R2 at preset temperature say CPU is 60C that would allow to adjust so fan would get 12V full power.

I found simple circuits with only lower limit, or complex PWM circuits, if you know a circuit like I need or perhaps how to modify this one here I would appreciate it:
**broken link removed**

 

[ronv]

So you want a 2 speed controller? 1 slow, 1 fast?

 

[smilem]

So you want a 2 speed controller? 1 slow, 1 fast?

Well I think the speed would be increasing from preset start temperature to preset top temperature. So the speed would be linear.

 

[smilem]

I think I found what I need here:
Guide - PWM Fan controller | bit-tech.net

"If desired, R1 and R2 can be replaced with 22K variable preset resistors to allow exact tailoring of the control range. Varying R1 will alter the maximum output, whilst R2 controls the minimum. Note these adjustments are interactive with each other and will require some trial and error to achieve the desired range."

 

[Reloadron]

Yes, the second circuit in your link will give you about what you want, some minor tweaking involved. This is a link to your ball game chip that makes things happen.

<EDIT> You may have to look for a distributor to buy just a few </EDIT>

Ron

 

[smilem]

Could anyone explain how Overtemperature Fault Output works?
I would like to connect a Piezo signal generator of some sort like this if fan fails:
https://www.elfaelektroniikka.fi/elfa3~fi_en/elfa/init.do?item=37-662-73&toc=20114

 

[Reloadron]

Could anyone explain how Overtemperature Fault Output works?
I would like to connect a Piezo signal generator of some sort like this if fan fails:
https://www.elfaelektroniikka.fi/elfa3~fi_en/elfa/init.do?item=37-662-73&toc=20114

An open-collector over temperature fault output is asserted
if the primary control input is driven above the normal
control range.

What they are telling you is the chip has a transistor output used as a switch. When a limit is exceeded it turns on. The little piezoelectric you linked to shows an illustration of using the piezoelectric with an open collector output transistor drive. From the data sheet it would be the image I have attached.

On another note placement of the sensor (thermistor) is important.

Ron