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.
In the figure we have a simple signal tracer circuit to be coupled to the volume control of an AM...
This circuit was found in documentation from the 90s, using components from that time. The...
This circuit, obtained from old documentation, allows the recovery of sulfated batteries. The...