In the figure we have a simple way to have a peak bargraph indicator. The amplifier is of the audio type, but operational ones can be used. The circuit is from Radio Electronics from March 1980.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...