This circuit is from an 80's Electronic Engineering. The base is a common operating and 4 single integrated voltage comparators. The circuit directly drives 4 indicator LEDs.
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...