This document presents a circuit design that adds frequency control to a conventional Wien bridge oscillator. The design achieves this by incorporating an op amp inverter into the circuit topology.
The text specifies that the low power OP-221 dual operational amplifier works well for this application. It provides the formula for the center frequency, which is determined by the resistor, capacitor, and a variable term dependent on the inverter gain.
An op amp inverter is added to the conventional Wien bridge circuit to provide frequency control.
The low power OP-221 dual operational amplifier works well in this circuit.
The center frequency is calculated as 1 divided by the product of R, C, and a variable term 1/4/a.