I would like to make a voltage controlled PWM fan controller.

Essentially I would like to replace the pot in this diagram with a 100k pot that is controlled by 0-12v DC:

Full article: http://www.overclockers.com/pwm-fan-controller/

I have looked but I am getting conflicting information and the last time I built something everyone told me I was using outdated methods that were pointless (turned out I done three times the work I had to because a single chip replaced a lot if it) and that tutorial is 4 years old.

Thanks in advance.

 

That circuit would require major surgery to provide a voltage-controlled PWM with a wide control range. As a simple alternative you could try one of my circuits in this article.

 

I would like to make a voltage controlled PWM fan controller.

Essentially I would like to replace the pot in this diagram with a 100k pot that is controlled by 0-12v DC:

Full article: http://www.overclockers.com/pwm-fan-controller/

I have looked but I am getting conflicting information and the last time I built something everyone told me I was using outdated methods that were pointless (turned out I done three times the work I had to because a single chip replaced a lot if it) and that tutorial is 4 years old.

Thanks in advance.

That circuit looks more or less OK - but the resistor in series with the output pin should be moved to in series with the pot wiper, othererwise there will be a strong sawtooth component from the timing capacitor superimposed on the PWM fed to the power device.

 

Oddly enough, pin 5 of the 555 is called the control pin. There are many variations on using a variable voltage on that pin to control the 555's output. Zero to 12V is not bad, so long as the power to the 555 is ≥ 12V. In other words, find the circuit you want to use for PWM and apply your variable voltage to pin 5. Not all will work, but most will.

John

 

The circuit I posted only sends a signal to a PWM fan. In no way is it designed to supply anything else.

I have a 0-12v control panel. All I want to do is remove the the pot in this diagram and replace it with one that is controlled by a voltage in the 0-12v range.

 

I have not seen a digital pot than handles 12V across its terminals. They may exist. Have you found one?

What's your question?

John

 

I have not seen a digital pot than handles 12V across its terminals. They may exist. Have you found one?

What's your question?

John

I haven't seen one. The only thing I have come across is this ...

http://www.maximintegrated.com/en/app-notes/index.mvp/id/4051

 

Why not use one of the circuits Alex referenced in Post #2?
No difficult-to-acquire digital pot required.

 

I would like to make a voltage controlled PWM fan controller.

Essentially I would like to replace the pot in this diagram with a 100k pot that is controlled by 0-12v DC:

Full article: http://www.overclockers.com/pwm-fan-controller/

I have looked but I am getting conflicting information and the last time I built something everyone told me I was using outdated methods that were pointless (turned out I done three times the work I had to because a single chip replaced a lot if it) and that tutorial is 4 years old.

Thanks in advance.

MCP41HV1 allows to voltage across the pot to exceed VCC rails.