Signal converter for DC and AC signals - has control circuit and at least one secondary circuit separated by optical coupler

摘要

The signal converter for d.c. and a.c. signals includes a control circuit and at least one secondary circuit separated by an optical coupler. A dynamically active signal evaluating circuit is provided in the control circuit, connected to the two signal wires. It contains a light emitting diode in the optical coupler, and the secondary circuit contains a phototransistor operating as a switch. It is connected to a supply current corresponding to the required signal type, and to a load resistor. The circuit can be extended by a fourth resistor (R4) in series with the control circuits and a diode (D1) in parallel with the 1.e.d. (LD). A npn transistor (T1) is coupled to the phototransistor (FT1).