This circuit for common analog telephones was found in March 1982 Radio Electronics magazine. It applies to lines that have an extension (second telephone).
This siren circuit was found in a Popular Electronics from March/April 1969. We can easily...
This power stage with two counterphase transistors and coupling transformers was shown in Radio...
This circuit is a sample of a DC amplifier used in the 50's. The transistor is germanium and very...