This sound meter or sonometer was found in a Popular Electronics from the 80's. The circuit can be easily implemented today, and the microphone is made of electret or ceramic.
We found this circuit with several types of sensors in a 1995 documentation. The circuit also has...
The A3906 integrated circuit from Allegro MicroSystems (www.allegro.com) consists of a single-step motor...
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...