FETboard rev3


Now when these are getting into the hands of more and more people, it might be a good idea for me to actually write a bit on how to use it…


On the far right side there is the 2×5 pin header for connecting it to the ramps AUX-2 port. These pins must be soldered on so they point down to connect with the ramps port correctly.

The IN, D44, D59, D66 and D64 I recommend soldering so they point up for easier access.

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The IN pins connect to the power supply directly to bypass the arduino and protect it from getting overloaded.


Each of the other pins can then be turned on with M42 or one of the automated functions already in the firmware for turning the pin on/off depending on hotend temperature and stepper driver status.

When connected to ramps the D44 even got PWM capability due to the ArduinoMEGA having pwm on D44-D45.


The mosfets on the board can handle 20A on one channel, but I only recommend a total draw of 3A on all pins. Meaning you can do 4x 750mA, 2x 500mA + 1x 2A, 1x 3A, 3x 1A, or what else you could fancy, as long as the total is 3A or less.

9 thoughts on “FETboard rev3”

    • First you need to sacrifice a small child, then give me your soul… Or, actually… I am working on a version for http://store.makerstoolworks.com/ so they will be available there, but not sure when they will be there yet. So far the boards are being tested by people I know to make sure they are ready for use without being a hazard in any way. 🙂

  1. Just what I need to drive a couple of fans in my 3d printer (Hadron)
    I haven’t been able to find any of these for sale, are they available anywhere?
    Is the PCB design/schematic available ?

    • I am still not done with these, have had too many projects going on. If you just need to drive some fans there are some smaller ones on ebay. http://www.ebay.co.uk/itm/160905708869 The one I made and still working on can handle a hot-end without any sweat, I would not recommend that with this smaller version though.

  2. Any update on availability of these as either a built unit or as design files?
    Starting to build another printer that will need multiple fan control


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