This circuit serves as a reference for the components used and the time. The circuit is from 1967 RCA documentation. MOSFETs from that time are used.
The circuit shown is suggested by National Semiconductor's Linear Applications Handbook. The base...
This circuit uses a pickup coil to take the signal from a telephone line without contacts. The circuit...
In this circuit, the transistors are NPN for general use and the phototransistors can be replaced by...