After a fun day with the family, this evening I went about replacing the under-rated transistors I had driving my braking mosfets with some BC337 ones. They have a more respectable 50v CE voltage rating and should work well.
I was offline and never bothered to check the datasheet for them. It's an NPN BJT transistor.. how hard can this be.
Cue the smell of atomized silicon and motors spinning out of control.
<insert expletives here>
Stupidly try the other channel...
<insert more expletives here>
Later, go read the actual datasheet. The 2N3904 has an EBC pinout. The BC337 has a CBE pinout. I built it with my transistors wired in backwards.
<insert even more expletives here>
I've now blown more power mosfets in the last week than I have in at least the last 5 years and I do terrible things with them. Then again, I usually don't just 'wing it' when the power involved could easily vaporize my wiring.
The main problem here is a combination of arrogance, the complete lack of much of my equipment, and the tiny form factor I've forced myself into. Keeping with my goal of fitting everything within the board cross section, the power section needs to fit in a rectangular cube 3/4x3/4x3in including connectors and the minimum space I need for the mosfets consumes most of that. So.. bench testing has been pretty much non-existent.
It works on paper. It physically fits. I just need to stop screwing up now.
I'll be rebuilding the power section again tomorrow. Good thing I keep a bin full of power mosfets and transistors around..