This circuit was found in the February 1983 issue of Radio Electronics magazine. It is a 4-digit circuit with dedicated integrated circuits, with no power supply indicated.
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...