This circuit was found in the February 1985 issue of Radio Electronics magazine. It is based on an AY-3-1350 melody generator that was common at the time. It is suitable for analog lines only.
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...