This circuit was found in a 1977 documentation. It limits the voltage from a source using zener diodes on the rectifier bridge. It is an unusual configuration today.
The LM150, 250 and 350 series are manufactured by several semiconductor industries that suggest...
This amplifier with gain control was obtained in a documentation from Signetics of the 80's....
The SCR sector of this circuit can be powered by high voltage AC and instead of the LEDs we can...