Found in the May 1971 Radio Electronics magazine, this is the circuit for a commercial high-impedance instrument. The circuit uses 4 transistors and is powered by 2 9 V batteries.
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...