This control circuit up to 1 kW was found in a 1967 RCA documentation. The components are from that time, and modern equivalents can be used.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
Found in 1965 General Electric technical documentation, this half-wave circuit controls shunt type...
The power supply shown in the figure provides voltages between 0 and approximately 15 volts, with...