This capacitive sensor that operates with a high frequency oscillator was found in Radio Electronics from the 90's. The circuit operates around 300 kHz.
We found this thyristor power supply in a 1987 documentation. It uses common SCRs as rectifiers and...
This 200-mW amplifier uses one of the first commercial power transistors. The circuit is from a...
This traditional oscillator circuit that can be found elsewhere in this section uses general...