We found this circuit in a 90s Radio Electronics. The integrated circuit used is uncommon today. The table indicates the components for different operating ranges.
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...