This circuit was found in the April 1993 Electronics Now magazine. With it, it is possible to control the gain of an operational circuit with a JFET.
This configuration appears elsewhere on this site. This is from a 90’s Popular Electronics and is valid for...
This circuit is from an Electronics World of 1968. The transistors are of the time and the power...
An way to change the frequency of the previous oscillator (CIR112E) is to add a variable capacitor in the...