This unique device completely eliminates hums and buzzes caused by ground loops. It compensates not only for level differences between systems, but for varying impedances caused by transformers and capacitance on the lines.

This device provides an electrically isolated interface between the two intercom systems. Either “side” of the interface can connect to a Clear-Com intercom system or an RTS intercom system, allowing Clear-Com-to-Clear-Com, Clear-Com-to-RTS, and RTS-to-RTS combinations.

In addition, the TW-12C passes through and translates “call” signals, Clear-Com-to-RTS and vice versa. The interface consists of two identical, 2-wire-to-4-wire hybrid networks which break the ground loops that occur when two systems are run from separate power sources. The audio paths are transformer-coupled and the signaling circuits are opto-isolated.