This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
The circuit shown in the figure is suggested by Intersil (www.intersil.com) and makes use of the...
This circuit was originally designed for communications applications. We found it in a 1980s...
This circuit is from a 1975 Motorola manual. The FET can be the BF245 and the output voltage...