Howdy! I've restored a few model train controllers in my time so far at the hobby that I've been really enjoyin it, (although I regret to say one is non-operational on my end) the controllers I perosnally like convert to 9 volts DC as they were normally originally 4.5 and 6 volts as a bit of a power upgraid, preferably 6 AA bateries are used because they are easily avaliable from many places, these controllers were made by Marx and are HO scale but produced in Japan, they are easy for beginner modelers that want to learn how to solder, but the contacts will need slight scruffing first to provide better adhesion to the solder... as the controllers only need about 8 solder joints and have two speeds but can be reworked to use a slide switch in theroy but will need slight tinkering, a scarlet or white grain of wheat bulb may also be optiomal as well to show when power is on.
I"m not resposible for any personal damages on your end, model at your own risk
"Peace and Love, Peace and Love" -Max