Hi @tekguy. Built that 4 years ago! A very handy instrument.
LM324 150W 10A Constant Current Electronic Load
Changes from standard kit:
x4 FETS changed to higher rated IRFP4468 130A 200v (preferably matched - see Reply #33. Other FETs are suggested by Forum members in the thread.
x4 FET Source resistors from 0.22R to 0.10R (5watt).
Added 15A automotive fuse and holder to input.
Added V/A digital panel meter with its own 7.4v 2S Li supply. Reply #15.
Added LM317 manual fan speed controller. A better design would be a heat sensing circuit to automatically switch on fan at a particular temperature.
Added 8.2R + 10uF snubber across input to suppress unwanted oscillation.
Added 7812 voltage regulator to stabilise TL431 and IC supply.
Added SPDT switch for local/remote input voltage sensing.
Added an additional 15K resistor in series with the helipot. The actual value depends on the final maximum current required.
Most of the parts are available on eBay and easily searched. Direct references are not given as they go out of date quickly as sellers change their listings.
Listing in Reply #35 may or may not work.
enut11
PS
Parts/kits seem to have changed since I built my electronic load 4 years ago. There are other designs, with fully built circuit boards and heatsink/fan already attached, available on eBay.
I did see the original kit that I built available from this supplier:
https://tinyurl.com/42ejr993The photo below shows the general layout including two heat-shields, made of thick cardboard, to isolate the voltage reference.