A PIC-based 8 to 16-Channel 2-wire on-off signaling communication link. An optional add-on interface extends possible options to internal private telephone and intercom systems.

This project provides up to sixteen channels of on-off signaling communication through just a single pair of wires, in one direction or in both directions simultaneously. In a one-way system the Transmitter may be powered through the same pair of wires, which allows the monitoring of up to sixteen inputs from locations having no local power supplies.

An interfacing option (in Part 2/June 00) enables operation through audio circuits, such as private internal telephone and intercom systems.

Although ideal for remote signaling and alarm system monitoring, other possible applications could include such things as environmental monitoring, model railway controls and switching for advanced lighting or display systems. The versatility of using circuit modules, and the ways in which they can be connected together, means that possible applications are limited only by the constructor’s own imagination.