# wein bridge oscillator

1. ## wein bridge oscillator

hello,
i am doing a practical on lm 741. i want to make it to use it as an wein bridge oscillator.the value of c1=c2=0.01uF, R1=R2=3K, Rf=2k, Ra=1k.accordingly the output frequency should be 5khz.bt my circuit is not working like.even its frequency is not stable at all.i think my circuit is not working.please tell me where is the fault.

the link for the image is given below:

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2. ## Re: wein bridge oscillator

To make it working you need a symmetrical power supply, for example : [+5V] - 0V - [-5V] .. see attached picture ..
Without that symmetry the inputs are incorrectly biased ..

Rgds,
IanP
:D

3. ## Re: wein bridge oscillator

thanks for the reply. but i am still confuse. i did not got what do you mean by symmetrical power supply as i am using regulated power supply for biasing.i have to use +5 and - 5 volt supply ?just give me idea about the symmetrical power supply and how to implement it.

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4. ## Re: wein bridge oscillator

You have to create situation similar to connecting two batteries (or two power supplies) in series, thus creating positive and negative supply with reference to the common connection, which you can call “virtual ground”, 0V or GND .. see attached picture or this website:
http://tangentsoft.net/elec/vgrounds.html

Rgds,
IanP
:D

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5. ## Re: wein bridge oscillator

The 741 OP-Amp Ic is a device which require dual supply to be operated.

6. ## Re: wein bridge oscillator

Hello preetikarki,

* The comment from IanP is correct since it is recommended to operate with a dual supply (for single supply the circuit looks a bit more complicated.)

* The comment from yasir is not correct. The 741 does not require a split supply.

* However, the most important point: Your circuitry is wrong!:

The resistive feeback must be inverting to form an non-inverting amplifier with a gain of (slightly above) 3. Thus, change the resistor ratio an d connect this path to the neg. opamp input.
The WIEN path has to be connected to the non-inv. opamp input.

*Please note, that the circuit is called WIEN oscillator. I know that in several books and articles the name is spelled incorrectly as "WEIN

7. ## wein bridge oscillator

As IanP has also said, you do need a ground reference for your power supply as well. It cannot be floating as it currently is.

Keith.

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8. ## Re: wein bridge oscillator

Fix the opamp inputs error and replace R1, R4 by two 2*R values to provide an offset voltage.

For minimum distortion, R2 (22k) must be the minimum value that assure the oscillation.

9. ## wein bridge oscillator

A very old LM741 cannot drive resistors as low as 470 ohms. Increase their value then decrease the value of the capacitors to keep the same frequency.

Your very simple circuit does not have an amplitude stabilization circuit so the output will be clipped with severe distortion.

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