In this note we are discuss about the Wein Bridge Oscillator and about its Circuit Diagram, Operation, Advantages and Disadvantages also. Welcome to Poly Notes Hub.
Author Name: Arun Paul.
About Wein Bridge Oscillator
The Wien-bridge oscillator is the standard oscillator circuit for all frequencies in the range of 10Hz to about 1MHz. It is the most frequently used type of audio oscillator as the output is free from circuit fluctuations and ambient temperature.
Circuit Diagram of Wein Bridge Oscillator
the circuit of the Wien bridge oscillator. It is a two-stage amplifier with an R-C bridge circuit. The bridge circuit has the arms R1C1, R3, R2C2, and tungsten lamp Lp. Resistance R3 and Lp are used to stabilize the amplitude of the output. The transistor T1 is an oscillator and amplifier while the other transistor T2 is an inverter (i.e. to produce a phase shift of 180°). The circuit uses positive and negative feedback. The positive feedback is through R1C1, and C2R2 to the transistor T1. The negative feedback is through the voltage divider to the input of transistor T2. The frequency of Oscillations is determined by the series element R1C1 and parallel element R2C2 of the bridge.
f = 1⁄(2πRC)
Where, R1 = R2 = R and C1 = C2 = C
Operation of Wein Bridge Oscillator
When the circuit is started, the bridge circuit produces oscillations of frequency determined by exp. The two transistors produce a total phase of 360° so that proper positive feedback is ensured. The negative feedback in the circuit ensures constant output. This is achieved by the temperature sensitive tungsten lamp Lp. It is resistance increases with current. Should the amplitude of output tend to increase, more current would provide more negative feedback. The result is that the output would return to its original value. A reverse action would take place if the output tends to decrease.
Advantages of Wein Bridge Oscillator
- It gives constant output.
- The circuit works quite easily.
- The overall gain is high because of two transistors.
- The frequency of oscillators can be easily changed by using a potentiometer.
Disadvantages of Wein Bridge Oscillator
- The circuit requires two transistors and a large number of components.
- It cannot generate very high frequencies.