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.
The circuit shown in the figure is a simple test of NPN and PNP transistors. The circuit detects the...
This circuit is from an old American documentation, from 1977, but it can be implemented with more...
Found in a manufacturer documentation from the 90s, this circuit makes use of period components. The...