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 below was suggested by the Motorola Linear Databook of 1990. The component used is...
This circuit is intended for testing small capacitors. What we have is an astable multivibrator, which works...
This circuit was found in an American 1980s documentation. The transistorized step is the...