This circuit has a gain of 6 dB for low frequencies from 85 Hz and can be used in a mini subwoofer. The circuit is from a Radio Electronics from March 1990.
Found in an Electronics Now from the 90s, this circuit can be triggered by an external control...
This micro FM transmitter uses a tunnel diode as an oscillator. I found it in an English...
Found in older American documentation, this circuit can monitor 3 or more voltages determined by...