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 precision speed control was obtained in an Electronic Design from the 90's. The output final...
This amplifier for old record players has RIAA correction and was found in documentation from the...
We found this configuration with a logic circuit that is now uncommon in an 80's documentation. The circuit...