It might be interesting, but it’s not going to happen. The Arduino controls the field current on the main generator, but that can only be loaded by having the loco pulling a load. My scope is mains powered, and we don’t have mains at the track. We do have a petrol driven genny, but I’d need a very long bit of wire. And anyway, I’m doing it as a favour, so it has to be fairly quick and dirty. It could possibly be done with a big bank of resistors, but they don’t generate back emf, so an important factor missing from the equation.
I don’t have any 0.5W resistors, so I’m going to put 2 off 200 ohm in parallel, these are from those packs of assorted and are I assume 0.25W. First off I’ll replace the display to get it working and check the current consumption running if off a bench power supply, then add resistors and make sure they don’t get hot. I’ll probably have to buy a zenner, anathema to a Yorkshireman.
I think the whole concept is wrong. He has the field control connected to the throttle lever, I’m sure it would be better with independent control, as if you wind up the field before the engine has revved up the engine is overloaded. I think he has allowed for this in software, but doing it my way could just use one of those motor controllers off ebay to control the field, and I doubt they have any delicate processors to worry about.
Thanks to all contributors, I’ll report progress