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 can be used in decoration or to draw attention, in a “fake” assembly for example. What he...
This sophisticated alarm with traditional components was found in an ancient American...
We found this AM radio in a 1957 transistor application manual, published by Raytheon. The...