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I am working on a project which requires me to create some sinusoidal signals at specific frequencies using a DC battery as the only power input. And I also want to tune the amplitude of the output sine wave lets say minimum -5/+5 Volts. To achieve that, I made some research and found that Wien-Bridge oscillator might be the solution. However, I cannot be sure that whether it can accomplish given requirements I mentioned above or not.

Does it take its input as DC? Can I tune its output amplitude easily?

And if it is not the solution I was looking, how can I get sinusoidal signals only using DC sources?

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  • \$\begingroup\$ You are speaking of "sinusoidal signals"....be aware that this is an ideal case, Each oscillator output ("called "sinusoidal") will exhibit non-linear distortions, which strongly depend on the amplitude control mechanism within the oscillator. Hence, it is important if you have any signal quality requirements? \$\endgroup\$ – LvW Nov 26 '19 at 18:42
  • \$\begingroup\$ Actually i tried some circuits and most top and bottom parts of the sine waves were little bit clipped like 0.2 V. So that should be considered normal? \$\endgroup\$ – muyustan Nov 26 '19 at 18:52
  • \$\begingroup\$ It is - more or less - "normal" without any additional means for amplitude control. If you can live with it - OK. Otherwise, you must use some non-linear elements (diodes for example) which can perform "soft limiting" (instead of hard-limiting resp. clipping caused by the power rail). \$\endgroup\$ – LvW Nov 27 '19 at 8:11
  • \$\begingroup\$ @LvW thanks, any recommendations on amplitude stability without too much effort and resources? \$\endgroup\$ – muyustan Nov 27 '19 at 10:26
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    \$\begingroup\$ I did not mention 1Mohm.....the goal is that RP||RF reaches the required value (for a gain of 3) for an output amplitude of some volts. You may start perhaps with RP=10*RF. \$\endgroup\$ – LvW Nov 28 '19 at 7:38
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Any sinusoidal oscillator generates a sine wave from a DC input. That's what oscillators do. (Though not all oscillators generate sine waves - many of them generate different types of waves)

The amplitude of the Wien bridge oscillator is not easily controllable. You could build an amplifier with adjustable gain, after the oscillator, to control the amplitude of the output signal. Since your minimum amplitude is 5 volts, you could also try adjusting the oscillator's power supply voltage, if the voltage range suits the power supply of your op-amp.

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  • \$\begingroup\$ What about using a voltage divider at the output? \$\endgroup\$ – muyustan Nov 26 '19 at 18:53
  • \$\begingroup\$ That also works. The output impedance will be higher. \$\endgroup\$ – user253751 Nov 27 '19 at 9:46
  • \$\begingroup\$ what do you mean by output impedance will be higher? Aren't output impedances of opamps low? In the range of 100 ohms maybe. \$\endgroup\$ – muyustan Nov 27 '19 at 15:02
  • \$\begingroup\$ @muyustan yes but the output impedance of a voltage divider is high. \$\endgroup\$ – user253751 Nov 27 '19 at 15:11
  • \$\begingroup\$ ok, so is it logical to load a speaker of 8 ohms to a voltage divider network consisting of a 100k pot wired to ground and a 100k fixed resistor and output taken from the potentiometer? \$\endgroup\$ – muyustan Nov 27 '19 at 15:24

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