This circuit was obtained in a 1970 engineering documentation. The operational is the 741, but other operational ones can be used. The power supply must be symmetrical.
This amplifier was published in the July 1961 Radio Electronics magazine. It announced the release of...
This circuit was found in a 1967 Electronics World. SCRs are according the controller load,...
This sophisticated circuit using a liquid crystal display was found in Radio Electronics from the...