A Wien bridge oscillator is a type of electronic oscillator

Electronic oscillator

An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in innumerable electronic devices...

 that generates sine wave

Sine wave

The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. It occurs often in pure mathematics, as well as physics, signal processing, electrical engineering and many other fields...

s. It can generate a large range of frequencies. The oscillator is based on a bridge circuit

Bridge circuit

A bridge circuit is a type of electrical circuit in which two circuit branches are "bridged" by a third branch connected between the first two branches at some intermediate point along them. The bridge was originally developed for laboratory measurement purposes and one of the intermediate...

 originally developed by Max Wien

Max Wien

Max Wien was a German physicist and the director of the Institute of Physics at the University of Jena. He was born in Königsberg, Prussia.Wien studied under Helmholtz and Kundt. He invented the "Löschfunkensender" during the years 1906 to 1909 and the Wien bridge in 1891...

 in 1891.
The bridge comprises four resistor

Resistor

A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...

s and two capacitor

Capacitor

A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

s. The oscillator can also be viewed as a positive gain amplifier combined with a bandpass filter that provides positive feedback

Positive feedback

Positive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that responds to a perturbation in a way that reduces its effect is...

.

The modern circuit is derived from William Hewlett

William Reddington Hewlett

William Redington Hewlett was an engineer and the co-founder, with David Packard, of the Hewlett-Packard Company . He was born in Ann Arbor, Michigan where is father taught at the Univerisy of Michigan Medical School...

's 1939 Stanford University

Stanford University

The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

 master's degree thesis.