Found in American documentation from the 1980s, this circuit operates in the frequency range 0.5 to 20 MHz. The power can be between 5 and 15 V.
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...