This diagram was found in the November 1972 issue of Radio Electronics magazine in an article describing benchtop equipment. The transistors are of the time and the frequencies are given by the coils.
This simple expandable circuit was obtained from a Popular Electronics from the 80's. The supply...
This traditional configuration found in a Radio Shack document can use 2N2646. More keys can be...
This circuit was obtained in an Argentine publication in 1976. It consists of a series voltage...