OK, first off, I understand the issues with MOSFETs in parallel, so this discussion isn't about that.
I want to try and build a 24V 20A capable current load that anyone can replicate using as few parts as possible. I'm planning on using it with the test controller software.
My main goal was keeping component count and cost to a minimum, at the moment the only things I think are questionable are:
1. Using a 2 output DAC instead of a single output DAC, but the single output 4821 is suffering shortages at the minute.
2. The LCD display could be deemed unnecessary, as you'll be able to see everything on test controller, but I decided some sort of local feedback was needed, so kept it in the base design.
Things like buttons, keypads, buzzers etc... can be added later. The point here is to get a stable base design and then the user can add "mods" like (for an example) a 3X4 keypad later.
As a base design, does anyone see any major issues here?
EDIT: Forgot to add, the Nano is getting its' supply via USB.
(Note, I'm aware that there is a GND2 labeled on this image, it should just read GND)
J2 is the Voltage sense for the load, J3 is the current input. 4 wire system for accurate voltage detection.
The LM324 is used as a control loop for the base input to the MOSFETs, and also as an amplifier for the current shunt which outputs 75mV at 20A.