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.
Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It...
The integrated circuit used in this project is uncommon today, as we found the configuration in a...
This variable high frequency oscillator circuit was found in an old English documentation. The...