Found in a 1980s American documentation, this crystal-controlled oscillator generates 100 MHz signals. The crystal used is 20 MHz. Modern equivalent transistors can be used.
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...