Use to expand your Digitrax or other DCC systems. Additional units provide more power to run more trains, automate reverse loops and simplify electronic isolation of portions of your layout so a short circuit stops only one area. Automatically shuts down if command-control drive signal is lost; layout will not convert to DC operation if a cable or connection is broken so train won't "take off" if they suddenly loose the DCC signal. Accepts 50/60Hz AC or DC from your current transformer, minimum input 12V AC or DC. Maximum input 22V AC or 28V DC. Auto reset for overheating and short circuit protection, with unique "smart" protection that won't weld derailed locos to the track. Each unit allows up to 22 operators and can be used with various Digitrax throttles, sold separately. Uses LocoNet Expansion Network for easy, reliable hook-up and future system expansion. All connections are made with six conductor telephone jacks and wire.