HF-1 High Frequency Electronic Track Cleaner - Single TrackThe 12v DC controlled output from the controller is passed through the unit. Connection between unit, power source, controller and track is achieved via six terminal connections. The unit superimposes a harmless high frequency signal over the output from the controller. When a poor contact between locomotive and rail is detected, the unit switches on, ionising the gap and burning off the dirt, switching off again when contact is restored. Compatible