Wein bridge oscillator

Aim: To study and calculate frequency of oscillations of Wein Bridge Oscillator and compare it with theoretical value.

APPARATUS:

TINA SOFTWARE

PC

CIRCUIT DIAGRAM:

Circuit highlighting the Bridge formation.

THEORY:

The Wein Bridge oscillator is a standard circuit for generating low frequencies in the range of 10 Hz to 1MHz.The method used for getting +ve feedback in Wein Bridge oscillator is to use two stages of an RC-coupled amplifier. Since one stage of the RC-coupled amplifier introduces a phase shift of 180 deg, two stages will introduces a phase shift of 360 deg. At the frequency of oscillations f the +ve feedback network shown in fig makes the input & output in the phase. The formula for frequency of oscillations is given as

f =1/2pvR₁C₁R₂C₂

If R₁C₁ = R₂.C₂ = RC, then f = 1/2 p RC

In the above circuit, f=1/2pv R₄C₂R₇C₁

PROCEDURE:

1. Start Tina. A blank circuit window will appear on the screen along with a component tool bar.
2. Using component tool bar place all the components on the circuit window and wire the circuit.
3. By making adjustments in the Potentiometer connected in the +ve feedback loop, try to obtain a stable sine wave.
4. Measure the time period of the waveform obtained on CRO and calculate the Frequency of oscillations.
5. Repeat the procedure for different values of capacitance.

OBSERVATION:

Given R=10kO, C=0.01µF

f_T = 1/ 2(pi)RC

f_P = 1/T

Amplitude,V₀ =

MODEL WAVE FORMS:

RESULT:

The frequency of oscillations of the Wein Bridge oscillator is calculated and is verified.

LEARNING OUTCOMES:

1. Students are able to Design and analyze Wein Bridge oscillator.

VIVA QUESTIONS:

1.Give the formula for frequency of oscillations in Wein Bridge Oscillator circuit?

Ans:

2.What is the condition for Wien Bridge oscillator to generate oscillations?

Ans:

What is the total phase shift provided by the Wein Bridge oscillator?

What is the function of lead-lag network in Wein Bridge oscillator?

Which type of feedback is used in Wein Bridge oscillator

What is the gain of Wein Bridge oscillator?

What are the applications of Wein Bridge oscillator

What is the condition for generating oscillations?

What is the difference between damped oscillations undamped oscillations?

Wein Bridge oscillator is either LC or RC oscillator.

What are the drawbacks in using Wein Bridge Oscillators?