This circuit makes use of an optical coupler to isolate the telephone line. The circuit is from 1970s documentation. The components admit equivalents.
This circuit was obtained from a 1966 General Electric documentation. It can serve as a basis for...
This 1967 Motorola circuit is intended for operation with signals up to 250 MHz delivering a 50 MHz...
The gain of this amplifier is controlled by light shining on an LDR. The circuit is from a Radio...