What is it?

PCB originally designed to control cooling fans on Raspberry Pi boards, but can be used with other small motors or DC loads. Includes a flyback diode to safely dissipate inductive voltage spikes.

Can also work with Arduino and other such dev boards.

Base price of 2-pac and 1-pac is the same, but selected options are doubled up with 2-pac at no additional charge.

Why did you make it?

Wanted a way to control cooling fans off of a Raspberry Pi. While some fans have PWM inputs, some do not and cannot normally be controlled. This transistor board works well with the GPIO fan control option in Raspberry Pi OS (which turns it fully on and fully off).

Not a full motor driver (i.e. it only drives in one direction) but can be used with other simple DC motors as well. Includes a resistor and flyback diode.

What makes it special?

It's very, very small, even compared to a prior THT version. It should therefore be able to fit inside nearly any case. The optional 90º headers are even spec'd out to be low profile.

Boards come fully assembled with or without headers depending on the option selected, and appearance of the boards may vary. Options also available for female-female wires as needed, and/or clear heat shrink.

Uses a surface mount 2222 transistor which is capable of passing .6A. Therefore not suitable for large loads, but capable of much more than the Pi's native outputs (or Arduino and other such boards). .6A is the theoretical maximum, but performance may degrade as it approaches that limit. Transistor may become hot when supplying power, and should likely be derated, especially used with heat shrink.

See notes/precautions starting at ~ 6:40 in video.

The video shows how to set this up in Raspberry Pi OS, but you can also use the script found here to have it check the temperature once per minute and react accordingly. This may be advantageous in some situations.

*Note that as of 6/14/2021

the board's input ground and GPIO input have been swapped (see connection images). New boards are black, and marked as such. This will be different than in the current video. This allows for easy alignment with the Raspberry Pi 5V, Ground and GPIO14 pins if you choose to use that particular setup.

*Note that as of 10/24/2021

I've been told that OS fan control for Raspberry Pi OS has been stripped out for anything earlier than the Pi 4. I don't know the details, but that's pretty disappointing on the surface. The bash scripts found in documentation should still work (though untested as of late), but that will take a bit more hacking than in the video seen below.

Depending on where it's shipped, you may owe import duties not included in price. Also, the inexpensive shipping service used generally takes a few weeks with kind of strange tracking. If you need it faster (and more costly), please message me and we can look at options.