Extruder External Mosfet Power Board

thingiverse

This board enables powering a Mk4/Mk5 Plastruder and Heated Build Platform via external mosfets while connecting directly to a stock Extruder Controller (EC) without modifications. The input lines connect to the EC's '-'(GND) terminals. After experiencing an EC mosfet burnout, the creator of this board designed it for silent powering and supporting PWM heating code for better temperature management. All outputs are protected with flyback diodes, allowing them to drive inductive loads like motors or other relays. This reduces current flowing through EC mosfets, preventing burnouts, and makes fixing/replacing easier on this board than the EC. Additionally, it lowers current going into the EC's Cat5 cable, potentially reducing communication errors. Tested with Mk4 Plastruder and HBP, it supports a Mk5 due to IRF520's 10A current capability. The design is open for additional cooling solutions or different mosfets, with heatsinks added for better cooling. However, be aware that this is the creator's first major circuit design, so errors are possible. Future improvements could include higher pull-up resistors and a master/emergency cutoff switch. The prototype was built on a proto-board, and pictures are available to assist with replication. Note that the original prototype deviated slightly from the schematic but was later updated with small signal diodes and powered Darlington pull-ups correctly in the final version. Pull-up resistors could be increased to 100K for reduced current requirements. Relays are optional, but a Darlington array offers extra protection for EC mosfets. Individual transistors can replace the Darlington array, and ensure proper wiring/traces for handling high currents.