Stereo preamplifier TDA3410 (CB21937E)

Taken from the 1982 SGS manual on integrated circuits, this preamplifier was used in commercial equipment at the time.

Delayed SCR trigger (CB19336E)
The circuit shown is from an old European publication. In it we have the way to activate a relay...
Audio Line Amplifier (CB4769E)
We found this circuit in a European publication from the 1990s. Transistors are still common types...
Active three-tone filter (CB20808E)
This circuit was found in an American documentation and can be added to common amplifiers of any...