The RCA integrated circuit used in this control is uncommon today. The circuit is from an Electronics Now from July 1995. The sensor determines the value of the adjustment potentiometer.
This circuit has already been presented from other manufacturers' manuals. This one, specifically, is from...
Other settings like this can be found on this website. This makes use of old operational...
This simple 555 component tester was found in the November 1992 issue of Radio Electronics...