This circuit consists of an electrostatic sensor that can check if a cable is energized by simply approaching it. The circuit is from an Electronics Now from December 1998.
We found this oscillator in a documentation for radio amateurs from the 1970s. The circuit can use...
Many oscilloscopes have high impedance inputs that make it difficult to observe high frequency signals...
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...