This circuit was found in the September 1972 issue of Radio Electronics magazine. The circuit uses an operational amplifier of the time and a symmetrical 9 V source.
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...