The purpose of this circuit found in the September 1977 issue of Radio Electronics magazine is to produce the vibrato effect. It is a phase shift circuit working with common operating systems.
This National Semiconductor circuit appears elsewhere on this site. The circuit must be powered by...
In this circuit the frequency is determined by the coil and the variable capacitor. Transistors like the...
This circuit is from old American documentation, but the transistor used is still very common...