4 channel mosfet mount for Wanhao i3 / Maker Select

thingiverse

I went searching for a dual MOSFET board to add chamber lighting and an additional controlled fan to my RAMPS setup but couldn't find one, however I did come across a cheap 4-channel MOSFET board. https://www.aliexpress.com/item/Four-Channel-4-Channel-Way-Route-MOSFET-Button-IRF540-V4-0-MOSFET-Switch-Module-For-Arduino/32859443480.html These aren't high-end fets like the ones found on a 3D printer controller - they have about five times the RDS(on) of the fets on a standard RAMPS, so you can't use these to power a heatbed and a hotend might be uncertain, but you can for sure use them to power LEDs and fans. Right now my RAMPS is set up in EFF configuration (extruder and two fans) with the heatbed MOSFET in bang-bang mode on pin 40 of AUX2. Marlin automatically turns on the print head fan when the hotend reaches 50C and turns it off when it drops below 50C. I've connected an LED strip to channel four of the MOSFET board. I could easily upgrade to an RGBW strip for color-coded print status. The vendor recommends using a 9V power supply to prevent overheating but this would only be a concern with high-speed PWM. The MOSFET doesn't get warm powering about two meters of LED strip. At normal PWM rates in Marlin, without enabling high-speed PWM, it should be fine at 24V as well. If they do get warm, it should be simple to stand up the fets and attach a heatsink, keeping in mind that the metal tabs have to be isolated from each other. By default there are five exposed hardware PWM pins on a RAMPS - four in the servos and pin 44 over on AUX-2. These days the average user might use one of these for a BLTouch, so you should have four hardware PWM pins available. FYI the MOSFETs on this board are active high, so you do not need to invert the signals.