I'm sure any purchase of LocoSound boards from MTH has long since passed. They also seem to want the old board back.
The LocoSound are wired very similar to the PS/2 boards, just with fewer options. They use the same tach sensor as PS/2, but there's an added 180 ohm resistor for some LocoSound steam, presumably for limiting current to the opto sensor LED. They do indeed use 6V incandescent bulbs and the standard PS/2 smoke unit configuration.
