I have a project, where a raspberry-pi shall measure temperature, and regulate a 12V non-pwm fan by modifying voltage throughput to the fan between 5V and 12V. The fan has a separate power-supply. Temp-measurement works fine already, but I need help building the circuit (being a beginner, I read tons of howtos and I think I got the idea, but I want to be a bit more safe, to not damage components)
As far as I understood, I have to achieve the following: Switch a Transistor (which is capable of handling the fan voltage & current) with a specific pulse, generated by a Raspberry GPIO-Pin configured as PWM-Pin and driven e.g. by python-scripts. => Smoothen the pwm-generated voltage output. The consumer in the circuit shall be a 12V Fan that uses only 0.125A peak.
Could anybody be so kind to explain how the circuit has to look like exactly and help me out calculating the correct values for those components ? Of course any ideas are welcome. I just need to achieve analog voltage regulation for that dc fan somehow. If I could read the fan speed in addition (from 3rd-pin, no pwm-fan), this would be additional benefit... Thanks a lot in advance, Oliver
PS : What software do you use to design circuit-graphics ? Are there any recommendations for open-source electronics-layouting ?!