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.
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...