This circuit was found in a 1945 publication. The circuit was stated to be part of a walk talkie. Note that, as it is a portable assembly, it was powered by batteries. The jack was for microphone insertion.
This circuit is from the National Semiconductor Audio Handbook. The amplifier operates with 6 V...
This is an amplifier that uses a pickup coil placed next to the telephone set and the listening is done in...
The modified Hartley oscillator seen in the figure can generate signals ranging from 3 MHz to 10...