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.
We found this circuit in the Linear Applications Handbook of the National Semiconductor of 1994....
This circuit was obtained from a 90sLinear Technology documentation. It is a current source that...
This is a possible circuit for the receiver of the previous circuit. Other circuits can be found...