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I want to control a nichrome wire with the PWM signal from a Raspberry Pi. The MOSFET modules that can be found on the net for the combination with a Raspberry became much too hot. So I decided to try a heatbed module from Lerdge for 3D printers, which can handle much higher loads.

Heatbed Module

I connect the control input to the Raspberry Pi 3+ I'm using and the power input of the module to 24V DC. To the clamps marked with Heatbed I connected both ends of the nichrome wire. The power led lights up and when I send a PMW signal from the Raspberry the control led flickers in time with the signal but the nichrome wire stays cold. I also do not measure any voltage between the heatbed terminals. No matter whether with or without PWM signal. I have three identical modules and they all behave identically. Therefore, I do not think that the MOSFET is broken.

Has anyone ever successfully controlled such a module with a Raspberry Pi (or similar) and can tell me where my error is?

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  • 3D printer motherboards tend to work from 12 or 24 volts. As such motherboards would typically drive the heater I'd expect the PWM input needs to be more that 3V3.
    – joan
    Jun 24 at 15:58

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Frankly I think such a module would be overkill just to heat a NiCr wire.

I use a suitable MOSFET with a heatsink to do similar, although I control with an Arduino (which has easier PWM and higher voltage).

Power MOSFET generally require a higher gate voltage than the Pi can provide. If you want to use the Pi you will need an amplifier to boost the PWM voltage such as a small MOSFET or transistor. If you need help designing such a circuit you should ask on the E&E site.

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  • It does work, when I use a logic level converter from 3V3 to 5V so you are absolutely right.
    – Jan Schmidt
    Jun 25 at 10:21

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