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 was obtained in a Popular Electronics of the 90s. The circuit uses integrated from...
This is not such a sophisticated application, as it uses the two timers of a 556 in its normal...
The frequency of this oscillator depends on the capacitor and R1 which can be changed. The circuit...