Visiting the lighting situation again in the ICE trains I spent an hour trying to trace the little circuit board which is so fiddly and given I have quite meaty multimeter probes it's pretty hard to figure out what's connected to what, it's a double sided board with at least one resistor on it, a three pin diode thing and a couple of other components.
I've almost zero idea what they're *for* because two of the wires go straight through the board to the lighting board.
Anyway, this is all digression. I detached the board from the led cluster and tried the pins with 3.3 V, leds lit up. Knowing that LEDs are diodes and have some reverse voltage resistance potential I ended up wiring them together in parallel, opposing each other.
I've then welded them into my embarrassment of a test loco:
and run it up to 50% speed in JMRI which is fast as I ever intend to take these locos, it seems to keep them below 5V on the motors that way.
If I can get my head and iron around stripping and soldering the enamelled wire I have then I should be able to get the light cluster back into the more beautiful loco I have running dcc I linked a few posts back.
I'd have loved to get them onto the extra wires from the dcc controller which are switchable power sinks, but I have no consistent DC supply in these trains, it's ac on the red and black and the DC that hits the motor obviously turns off, flips polarity and changes.
I think I might have murdered my raspberry pi though by stealing volts out of its headers, I expect I pulled too much current or something. I'm pretty bad at electronics when all's said and done.
Anyhoo, thanks for reading. Any and all comments about what I'm up to are welcome.