I still have the old controllers for the HO set, must be 35 or more years old, not sure were they are exactly. Most LGB is run up to about 24v, been running 18v from a DSE Lab power supply, and a small 3Amp pwm with trimpot and FWD & Reverse, its oh for testing but it is recommended to be capable of about 10Amps, power consumption soon adds up with a lot of gear running Sound, smoke units and lighting.
There where quite a few 7 1/4" gauge locos built between friends, one was build out of a old Yamaha 100, the wheels where machined on fathers lathe, had chain drive to front and back axle, the rest of it was built out of junk he had around the house, I think he built it about a week, it looked the part and the kids at the park loved it, it run for years and was one of the most reliable loco that was running at the club, it did a few more years at our own track, the only fix it needed was the exhaust port carbon up, cleaned that up and it went like a rocket also used to add some diesel to the fuel and it sounded and smelt more authentic. The same bloke also built a Heidi steam loco, he was battling a health issue so built it in a hurry, he got a few runs around our track with it, before he passed. 2 Other friends built some nice Locos, one had a Honda powering his, built the clutch himself and had the linings bonded onto the plate, power driven through an outboard leg, the other had a B&S Motor. Another fella built his loco around a Ford Prefect engine, AC compressor for air horn and air operated brakes, looked the part and worked really well very good work for someone who spent little time at school and didn't read or right, his loco is now somewhere around Toowoomba.
There is one getting built at the moment by a friend, 7 1/4" gauge loco its all electric, would like to see how he has ridged it all up, he has a bunch of G gauge locos he brought over for me to install sound cards and speakers into, in doing so have learnt a lot myself, some are easier than others, just did a sound card install in a USA Trains SD40-2, everything fit in the fuel tank.
Actually have some casting's in the shed to build a steam loco, boiler parts as well, job for I time when I have nothing else to do.
Always like the big loud stuff, just can't afford it.