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.
We found this version of the siren that makes the American police siren sound in a 1980...
This microphone circuit was found in a collection of American 80's layouts, using operational...
The integrated circuit used in this filter is like to a double 741 and must be powered by a...