Which sine wave circuit is the most stable and reliable?

liweiliang

Which sine wave circuit is the most stable and reliable? [Copy link]

I used an op amp to build a Wien bridge sine wave generating circuit, but the result is not ideal. The frequency and waveform will change when the voltage changes slightly. I repeatedly adjusted the resistance on the bridge, but the result is only trapezoidal waves. The working point for forming the sine wave is very narrow, and the performance is unstable. I would like to ask experienced people to give me some advice: Which sine wave circuit is the most stable and reliable?

xiaoxif

It can be said with certainty that the Wien oscillator itself is a relatively ideal low-frequency signal generator circuit. ' If the oscillator is considered to be composed of an amplifier and a frequency-selective feedback loop (Wen bridge), in addition to paying attention to the frequency selection of the Wien bridge, it is especially important to control the equivalent gain G of the op amp through the negative feedback branch to obtain a relatively ideal result . You did not give your specific design (circuit diagram) here, which is obviously insufficient for everyone's discussion and not enough for everyone to give you ideas. Do you agree? As it happens, I have a nice PPT file at hand. It has been converted to PDF format and is in English. Please refer to it as attached: Wein Bridge Oscillators Presentation-Darren.pdf (129.69 KB, downloads: 212)

2010-2-17 23:22 上传

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[ This post was last edited by xiaoxif on 2010-2-17 23:25 ]

liweiliang

Yes, I used this circuit. For the convenience of adjustment, the four resistors on the bridge are all adjustable. The result I got is that the range of the sine wave that can be adjusted is very narrow, the amplitude and frequency of the adjusted waveform are not very stable, and the voltage changes slightly and it is distorted. This is not what I want! It is very easy to get a trapezoidal wave. Even if the voltage changes greatly, the amplitude will be quite stable except for the frequency. I also used diodes and field tubes to stabilize the amplitude, but I can't see any obvious effect. Maybe my requirements are not practical?

qixiangyujj

Possible

liweiliang

I feel like the conditions for forming a sine wave are too harsh!

liweiliang

Some special integrated circuits contain sine generating circuits that can operate over a wide voltage range without variation. I wonder what that is like?

xiaoxif

I am still going to continue with your question about the first floor location. I originally planned to find some old information for your reference, but I didn't find it! Now I have found a similar design, sorted it out and wrote down some issues to pay attention to, and posted it together. If there are any mistakes, please correct them. This is the electrical schematic: EEW05.pdf (87.47 KB, downloads: 52)

2010-2-20 21:58 上传

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[ This post was last edited by xiaoxif at 2010-2-20 22:00]

liweiliang

Thanks xiaoxif! I use 324 and 741, and I feel that the sine operating point adjustment range is too narrow. If the power supply voltage or temperature changes slightly, the waveform will be distorted, which is far from what I hope? !

xiaoxif

The design and debugging of the sine oscillator of the Wien bridge (including device selection) is a bit troublesome. So I have asked you to provide your circuit before, otherwise there is no way to discuss it in detail, and the rest is probably either a random shot or stop here.

tiankai001

It's best to post your circuit so that we can prescribe the right remedy. Does the stuff you created need to be kept strictly confidential?

liweiliang

Please don't laugh at me! I don't know how to paste pictures yet. When I asked xiaoxif for help before, it was someone else who pasted them for me! I have to learn it quickly! This time I used a breadboard to build a Wien bridge to understand the sine oscillation circuit. The actual circuit is exactly the same as the one introduced by xiaoxif! And my feeling is that the sine operating point of this circuit is difficult to adjust and is extremely unstable. It is easily affected by the power supply voltage and temperature! If so, will it have practical value? I am a beginner and know very little, so I want to know if there is a better and more stable one!

leang521

Who has time to build a DEMO?

eguotangseng

It is better to use DDS module.

游蜂

Actually, there are many methods to generate sine waves, among which single chip microcomputer with D/A is very convenient. The cost is also very low. The Wien bridge used by the OP is also very classic. Your question is that two diodes (with opposite polarities and connected together) should be connected in series to the feedback circuit, so that the feedback will automatically adjust with the change of amplitude. This solves the amplitude problem and the frequency range can also be improved. This is explained in many textbooks.

simonprince

I think LZ can try LS's method. This kind of feedback is indeed used in many places.

yuehan319

Try the chip or chip, DDS is still very cost-effective.

leecoyui

Use diodes or transistors to fold the line, and you can get a good sine wave