This circuit is from a 1970 General Electric documentation. It can be found with variations on this website. The components used are common today.
This circuit was found in Radio Electronics magazine from February 1962. The sensor is an LDR, and the...
This circuit carries small batteries of Nicad that can be connected in series in number of up to...
This circuit was found in a 1967 US documentation. It shows how to build a gain control by digital...