This sound intensity meter was found in a 90s Elektor. The circuit uses an integrated device from the time that is not common today. The indicator is a milliammeter.
This circuit, found in a 1964 US documentation, consists of a selective amplifier that lets only...
The circuit shown in the figure has elements for maximum gain at maximum speed. By setting the...
Alongside the diagram of this control, which we find in a 1980s documentation are the component...