This circuit was found in the September 1997 issue of Electronics Now magazine. The circuit uses two op-amps and includes the symmetrical power supply.
This circuit was indicated in an old American publication to serve as a Laser alarm system as a...
This circuit, which uses only transistors as active components, was found in a 1987 documentation. The...
This sound meter or sonometer was found in a Popular Electronics from the 80's. The circuit can be...