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 an old 1980s documentation. The circuit can be implemented with modern...
This circuit is from a Linear datasheet. The circuit provides a 5 m voltage with 40 mA from an AA...
The components of this filter are calculated using conventional formulas (see mathematics section of...