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 high impedance step suggested by an English publication can operate up to 1 MHz with 1 V rms...
This timer of 10, 25, 45 seconds and 5 minutes has its times selected by the keys. The circuit drives...
When the power is turned on, the output that goes to the high Iogic Ievel is not necessarily the...