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For a better sine wave

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Hasan2017

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Hello sir,

This post might be a silly one, but my stupid brain does not find it well.:-?

I am looking for a signal generator circuit to fed different frequencies in other circuit.
I have found one, take a look
sine_wave_generator.jpg

But, the person who posted this did wrong on inverting and non inverting sign.

Anyway, I simulate this circuit, but noticed that the peak of sinewave is not much sharp rather than it flat.
Take a look this circuit, I found measurable change while screwing the POT R3.
sine_wave_simulation.PNG


Kindly discuss this design again.:smile:
1. Feedback path.
2. Inverting and non inverting inputs with filter.
3. Contribution of the potentiometers here.
4. Reason of using follower op amp.
5. Further improvement.
 

It's basically a Wien bridge oscillator, and the feedback path is connected correctly. https://en.wikipedia.org/wiki/Wien_bridge_oscillator

Wien bridge requires two equal RC circuits, using a single potentiometer for frequency adjust is a bad idea. The biggest problem is the lack of an amplitude stabilization circuit, an undistorted sine is effectively impossible without it.

A few links to related previous discussions

https://www.edaboard.com/showthread.php?t=178535
https://www.edaboard.com/showthread.php?t=202018
https://www.edaboard.com/showthread.php?t=232503
https://www.edaboard.com/showthread.php?t=236353
 
Never trust a circuit where nearly all resistors are made variable, especially when in that kind of oscillator the values should be matched. It usually means the designer had no clue what values to use so they made everything adjustable.

Brian.
 

Never trust a circuit where nearly all resistors are made variable, especially when in that kind of oscillator the values should be matched. It usually means the designer had no clue what values to use so they made everything adjustable.

Brian.

:thumbsup:
Correct, Brian. People who fiddle with a circuit until they miraculously "make it work". Then publish that on the web, adding to the thousands of pieces of junk already on the web.
How many times we have seen here and other electronic fora, postings similar to this: "My XYZ-5 circuit is not working, please help". Followed by an error-ridden schematic?

Now, I'm not opposed to some trimpots. But the article should at least indicate the initial settings of those trimpots, and how to adjust them to obtain correct circuit operation.
 

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