This dynamic mixer allows for smooth adjustment of the signal's passage from one channel to another. We found it in an American documentation from the 70s.
This simple electroscope with bipolar transistors is not the most sensitive, but can detect static...
This oscillator for various frequencies was obtained from a 1980s telecom documentation. The...
This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V...