I add Tomar LED lamps to my cabooses. I wanted a way to shut off the lamps when not in use on a siding. I don’t run interior lights. I was intrigued by Rivarossi’ magic wand in their HO cars. Not available at this time. I find this on Amazon. A turns the lights On. B shuts them off. Pretty simple and works as advertised.
Got it working using track power. Worked well but at times it would go out. Probably from dirty track, rollers or wheels. You would have to reactivate it to get it back working. Figured I’d try a battery. Less drag without rollers and wipers. Figured the amount they would actually get used the battery would last a good long time.
Hook up is simple. Red and Black go to a 9v battery. The other 2 control a relay for the lights. I used a resistor to get just under 3v for the lights. Seems simple enough. Except the battery drains a little each day. Somehow it must have a draw on it. My guess is after a weeks time it wouldn’t have enough to power up the board. I’m somewhat electrically challenged. I can follow instructions if someone has any ideas on how to isolate the battery when not in use.