12v Fan speed controller

This is a difficult thing to find. I do not want to control a AC fan or a celing fan, or any kind of ventilation fans with 3 push buttons.

I mean a 12v Fan, like the one inside a PC. What device can do that, and can be controlled in Home Assistant.

Usage: I have boat with a water based central heating system. Hotwater is pumped from the burner to radiators in each cabin. In the saloon and cockpit there are heat exchangers with a fan that blows hot air.

Now I want to add 12v fans to the radiators for better airflow, and I want to control the 12v fan in the heat exchangers.

I want to control not only on/off but also the speed of the fan.

DIY? That’s a PWM output in ESPHome (with a MOSFET or BJT to drive the 12V from 3.3v). Which you can then use in a fan component.

Unfortunately I don’t know of any off-the-shelf devices. Someone else might.

Is this for the power supply or do you need to step up the pwm control to 12v as well? I also would like to control a few variable speed case fans but I do have a seperate dedicated 12v supply.

After some digging I found the pwm control is indeed 5v.