This is the 1968 MR480 commercial cassette recorder circuit. The circuit was fully transistorized and powered by 4 large batteries. We found the diagram in a Japanese documentation of the time.
This circuit consists of a booster for the medium wave band. We found it in an English publication from...
This circuit converts signals from the 350 kHz to 500 kHz longwave (VLF) band to the 4.35 to 4.6...
This circuit of old documentation can be implemented with modern operational amplifiers. The...