This circuit is from a Hands-On Electronics from the 90s. The integrated amplifiers used are well known. The range is a few tens of meters depending on the resistance of the cables.
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...