Another project courtesy of GRJ, Automatic cab light control, Rule-17 lighting, and smoke intensity control for diesels.
Link: https://ogrforum.ogaugerr.com/...rol-lighting-in-loco
The module senses voltage on the loco motors, and when the loco is stopped, a relay turns on the cab light, dims the front and rear headlights, and reduces the smoke intensity. GJR included Gerber files and BOM. This uses surface mount components. He includes a wiring diagram for TMCC diesels. I believe it could be adapted to other control systems. Boards at OSH Park were 3 for $4.40 in 2018.
He also included a smaller, cheaper simpler version without the smoke effects. The smaller boards were 3 for $2.15.
Bob