Dc throttles available?

[Steamtrains]

Hi...All of the parts can be found at Radio Shack, with the exception of the voltage regulator, the OP AMP, and the "Darlington" transistor. I used a PC board and the case from RS, makes building it much easier. I also added the green light to indicate the unit is ON, and the ON/OFF switch. The other parts I ordered from Newark Electronics, they're surprisingly cheap..!!
Go for it...you'll enjoy it...!!