You can use a transistor to pwm the 12v input to the fan. I used IRLZ44n to this effect since they work ok at logic level. There are better transistors but the principle is the same
You can use a transistor to pwm the 12v input to the fan. I used IRLZ44n to this effect since they work ok at logic level. There are better transistors but the principle is the same
The pot is if you want to control the speed manually. The transistor if you want to control it from the pi (from the temperature for example).
If you want a potentiometer, there are two ways I think :
Have the potentiometer plugged to the pi ADC input, and in software regulate the pwm output to the transistor based on the signal coming from the pot.
Another way is to have the potentiometer in series with the fan and only control it from the pot. I’ve never built any circuit like this so there may be consideration to be put into the max current the pot can handle, but I guess for a small fan it could be okay.
In both cases you’ll need a 12v source. Either a 12v power supply, or a DC step up from 5v (from the 5v power supply (maybe the same as the pi), not from a pin on the raspberry as it can’t draw much current). In both cases, the grounds should be tied together so they all see the same voltage in reference to ground.
I can help you further if you want, but don’t hesitate to ask a LLM for it as they can be quite good now for such circuits, and can in theory explain concepts you don’t yet understand.