Hotbed SSR or Mosfets

  • I am setting up my core XY, finally got 98% of parts.

    I would like to have suggestions about going Mosfets or SSR with my Duet 0.8.5.

    I have read the

    Low voltage (12V or 24V) DC bed heater

    Use a low voltage drop DC/DC SSR such as the Auber Instruments MGR-1DD80D100 or Crydom DC100D40. The SSR may need a heatsink, depending on the current. Do not be tempted to use a cheap DC-DC SSR such as the SSR-40DD, which is basically useless for this application because of its high voltage drop.

    But a lot of people are suggesting Mosfets.

    Also, I found

    Duet 0.8.5

    The safe bed heater current has not been measured, but should be somewhat above 10A because the PCB trace between VIN + and Bed Heater + is wider than on the Duet 0.6. As with the Duet 0.6, you can solder a thick wire between the Power In +( VIN ) and Bed Heater + terminals on the back of the board to increase the current capacity. The bed heater terminal block is larger than on the Duet 0.6.

    Is there a source with video or image of the procedure to make sure that I do not burn my duet board?

    Thank you.

  • Been using an external mosfet board recently and written up my experience here:,763703

    Better than an electro-mechanical relay, not much different to a DC-DC SSR inhow it works, but seems to be more suited to 3D printing as they are designed for it.

  • Thanks for the link

  • I have recently switched to an off board mosfet since before I got my duetwifi. Works fine.

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