# Op Amp circuit for a sine wave

Discussion in 'Homework Help' started by EvilGenius2222, Sep 16, 2018.

1. ### EvilGenius2222 Thread Starter New Member

Sep 16, 2018
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I need to build an op amp circuit to build a 2 V P-P sine wave, 1 KHZ frequency with a 1.5 V DC Bias. Can anyone help with the design of the circuit im not entirely familiar with op amps. Thank you.

2. ### AlbertHall AAC Fanatic!

Jun 4, 2014
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A phase shift oscillator:

A wien brdge oscillator:

A wien bridge oscillator with amplitude stabilisation for lower distortion:

What level of distortion would be acceptable for this sine wave?

Mar 10, 2018
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The 1.5 Bias, you mean you want the sine to be offset from ground
by 1.5V ?

Something like this ?

Regards, Dana.

4. ### EvilGenius2222 Thread Starter New Member

Sep 16, 2018
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Im not quite sure about distortion just like im not one hundred percent about the theory behind the circuit.

5. ### ScottWang Moderator

Aug 23, 2012
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Is this a Homework?
If not then what's the load and purpose for this circuit?

6. ### EvilGenius2222 Thread Starter New Member

Sep 16, 2018
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This is an independent study project , and that was the only info i was given. I've never used/herd of op amp before so i did a lot of research online and i get the gist im just having a difficult time correlating it to the info i was given.

7. ### MrAl AAC Fanatic!

Jun 17, 2014
5,267
1,135
Hi,

An op amp is a device that amplifies the difference between two signals. It is almost always used with a feedback circuit to perform linear amplification which is used for different types of circuits.
For the phase shift oscillator it is used to provide a certain amount of gain as well as 180 phase shift.
BTW the phase shift oscillator also needs to have some form of amplitude stabilization added to it which is usually some kind of clipping. The gain must be kept at a certain value in order to maintain oscillations yet not cause the output to ramp up and saturate.

Apr 5, 2008
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Hello,

It will give you enough theory to build the circuit.

Bertus

File size:
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9. ### PsySc0rpi0n Well-Known Member

Mar 4, 2014
1,433
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I am interested in this circuit. I built the schematic on LTSpice but I have no idea of component values like resistors and capacitors. For the transistirs, would 2N222 (or 2N222A) suit the application?

I was reading somewhere about the RC series and parallel setup for the Wien basic bridge and about the resonant frequency. So I tried 1kΩ resistors and 1uF capacitors for a 160Hz resonant frequency. Then I simulated in LTSpice with a Small AC signal and Decade type from 1Hz to 100Khz. Apparently, the resonant frequency is about 90Hz.
I'm probably doing it wrong, so I would like to start from here.
I have attached the circuit.

File size:
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10. ### Alec_t AAC Fanatic!

Sep 17, 2013
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Many folk here won't open zip files for security reasons. This site will accept .asc files.

Apr 5, 2008
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Hello,

@PsySc0rpi0n , That is not what the OP is looking for:

That is not using an OpAmp.

Bertus

12. ### PsySc0rpi0n Well-Known Member

Mar 4, 2014
1,433
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I have been told more than once to use .zip files instead of separate files. I have there .asc and a .plt file.

I used that circuit that was suggested by Mr. @AlbertHall .

13. ### EvilGenius2222 Thread Starter New Member

Sep 16, 2018
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Like i said i get the gist of OP Amps i just am a little stuck on applying the given information i received to a circuit. Like where does the bias come in the circuit?

Aug 23, 2012
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15. ### PsySc0rpi0n Well-Known Member

Mar 4, 2014
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I think he doesn't know from where to start. That's why I picked up one of Mr. @AlbertHall circuits suggestions and tried to make it work. But then Mr. @bertus said that that circuit was not what the OP was looking for! So I waited for some reply from Mr. @AlbertHall. But nothing so far!

16. ### AlbertHall AAC Fanatic!

Jun 4, 2014
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Plenty of other posters, but not much from TS.

17. ### PsySc0rpi0n Well-Known Member

Mar 4, 2014
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Yes, I know, but I mean I was waiting for you to say if the suggestions you made were (or not) intended for the OP purpose or not and if so, why Mr. @bertus said the circuit I chose from the ones you suggested was not what the TS needed!

Apr 5, 2008
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Hello,

That is why I posted the application note about sine wave oscillators.
In there you will find different types with their pro's and con's.

bertus

JoeJester and atferrari like this.
19. ### crutschow Expert

Mar 14, 2008
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I don't think that was on this forum.

20. ### crutschow Expert

Mar 14, 2008
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The amount of distortion that can be tolerated depends upon the application.
What will you use the signal for?