We wire ours using diodes and the 14-volt AC tap from the transformer as shown in the Tortoise instructions. An added bonus is that the Tortoise machine has an internal resistance of 600 Ohms which allows you to put bi-color LEDs in series with the machines to indicate their status. The current draw on Tortoise machines is so low you can connect a bunch of them. You can even use 9-volt batteries if you have a module so you don't even have to tap the track buss.
