This is the commercial circuit for the TRF-44 amplifier sold in Japan in the 1960s. The circuit provides a few hundred milliwatts and is intended to be used as small, battery-powered turntables.
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...