The QTU (Quad Throttle Unit) by Howard Amos is intended to be a throttle (controller) unit for use on a model railway. In fact four throttles are built into a single card. These four throttles can be used as conventional manual throttles by connecting potentiometers for speed and switches for brake and reverse. Inertia potentiometers can also be added so that speed changes are gradual. Track circuiting (current detectors) are built-in and these could be used to drive lights on a control panel. QTU kits are available as full kits and as partial kits containing just the hard to get parts. Only Howard Amos's Tcc software is currently (2008) capable driving QTU's.