Talk:Voltage-controlled oscillator

VCXO

What is being talked about in the para I deleted is not a VCO as such but a VCXO ( voltage controlled crystal oscillator.) Because there will be a great deal of material to put on the VCO article on pure VCOs (when I get round to it),I am of the opinion that VCXOs should have a separate page.

Please reconsider your reversion of my edit.212.74.96.201 04:12, 1 August 2005 (UTC)

VCXO and Voltage-controlled crystal oscillator currently redirect to a section of this article. WP:SPLITTING this off does not seem necessary at the moment. ~Kvng (talk) 15:40, 22 February 2020 (UTC)

VFC

VFC appears in the Chips section. The acronym is not defined and is unfamiliar to me. --Kvng (talk) 19:40, 15 October 2011 (UTC)

Ah, Voltage-to-frequency converter ~Kvng (talk) 14:10, 10 April 2020 (UTC)

Electronic oscillator vs Harmonic oscillator

I'm concerned about the link to harmonic oscillator in the second section, which gives a misleading impression. I think instead it should point to Electronic oscillator#Linear oscillator, which is what we are talking about in this article. The physics concept harmonic oscillator is not the same as a linear or "harmonic" electronic oscillator circuit, although unfortunately they have the same name. A linear electronic oscillator circuit consists of a gain element such as a transistor in a feedback loop with an electronic filter; both parts are necessary. The filter MAY contain a "harmonic oscillator" device such as an LC circuit or quartz crystal, or it may not; RC oscillator circuits don't contain "harmonic oscillators" at all. Glrx, nontechnical readers will click on the harmonic oscillator link to try to find out what a linear electronic oscillator is, and will not find anything about electronic oscillators and precious little about circuits of any kind. They'll be confused. --Chetvorno^TALK 18:08, 14 March 2013 (UTC)

The recent rewrite of the section is an improvement, but the link in the title, harmonic oscillator, still points to the physics harmonic oscillator page, which has nothing about electronic oscillators. --Chetvorno^TALK 00:33, 15 March 2013 (UTC)

I disagree. When someone says "harmonic oscillator", then I think they invoke the concept in physics. There are coupled energy storage elements in a second order differential equation that sing in harmony. High Q resonator-based oscillators fit the bill. I don't recall that the discussions about RC oscillators ever found sources one way or the other. I don't consider RC oscillators to be harmonic oscillators. The article should have a link to other electronic oscillators (which the lede has), but I don't see why "harmonic oscillator" should necessarily link to electronic versions. Glrx (talk) 03:20, 16 March 2013 (UTC)

Here are some sources confirming that RC oscillators are linear "harmonic oscillators": 1, p.213-214, 2, p.220, 3, p.280, 4, p.224. Take a look at the phase shift oscillator and Wien bridge oscillator, the two main types of RC oscillator. These are linear oscillators that produce sine waves. In fact you'll find Wien bridge oscillators in signal generators that produce "pure" low distortion sine waves to measure harmonic distortion in audio systems. But no tuned circuits or high Q resonators; not a "harmonic oscillator" in sight. --Chetvorno^TALK 04:52, 29 March 2013 (UTC)

RC oscillators may or may not be harmonic oscillators, but RLC circuits definitely are. In the early days of RLC circuits, it was usual to use the mechanical analogy. Now, it is more usual to use the electronic circuit as an analogy for understanding mechanical oscillators. Gah4 (talk) 00:20, 23 February 2020 (UTC)

Continuing this, since no-one else commented, the physics harmonic oscillator is, in theory, the result of a linear second-order differential equation, which is a sinusoid. I suspect, then, that non-digital electronic oscillator circuits that generate sine waves qualify, and ones that don't, don't qualify. An RLC circuit needs gain to keep generating a signal. But relaxation oscillators are not harmonic, and many other electronic oscillators also are not. I suspect that both links should be here. Gah4 (talk) 17:21, 10 April 2020 (UTC)

Note, for example, that in Radio_transmitter_design being sinusoidal is important. It is much easier to generate a sinusoidal signal, than to filter some other shape. When harmonics don't matter, then other designs are fine. Gah4 (talk) 23:59, 10 April 2020 (UTC)

Questions and comments

1a. Is the image of the circuit labeled as "Voltage-controlled oscillator schematic - audio" a harmonic or a relaxation VCO oscillator?

1b. What kind of input is fed into Vin? AC? DC?

2. Aren't relaxation oscillators called also nonlinear? If they are, it should be added just like for linear/harmonic.

ICE77 (talk) 03:58, 31 July 2015 (UTC)

It's a relaxation oscillator. Vin is a DC voltage. The whole Types of VCO section needs a bunch of work (see tags inline and otherwise) and these points are the least of the issues there. ~Kvng (talk) 14:48, 2 August 2015 (UTC)

Kvng, thanks for the feedback. I add a few other questions.

1c. Is the image an example of grounded-capacitor VCO, an emitter-coupled VCO or a delay-based ring VCO?

1d. Is the image an example of one of those "Audio-frequency VCOs for use in musical contexts were largely superseded in the 1980s by their digital counterparts, DCOs"?

1e. I simulated the circuit in the image and I saw the triangular and square waveforms which increase in frequency with increasing voltage. Is there an equation that relates voltage, resistance and capacitance to frequency?

2. Could you comment on this? I didn't quite understand if relaxation oscillators can also be called linear oscillators? I think they can but I wanted to get a confirmation.

3. The text says "Relaxation oscillators can generate a sawtooth or triangular waveform".

Shouldn't the relaxation category include square wave outputs too?

4. The text says "Harmonic oscillator VCOs have these advantages over relaxation oscillators".

Is the comment limited to VCO relaxation oscillators only or is it extended to all relaxation oscillators?

5. "The frequency of a ring oscillator is controlled by varying either the supply voltage, the current available to each inverter stage, or the capacitive loading on each stage."

Does this imply that the ring oscillators are a type of VCO oscillators or the other way around?

6. The text lists Clapp and Colpitts circuits as VCO oscillators. In the electronic oscillators article they are classified as harmonic/feedback/LC oscillators. Is the LC oscillator a type of VCO oscillator or the other way around?

7. The text says "VCOs may have sine and/or square wave outputs."

Shouldn't sawtooth and triangle waveforms also be listed?

8. "From the 1990s on, pure software is the primary sound-generating method, but VCOs have become popular again often thanks to their imperfections."

How can something resurge in popularity if it has defects? There should be an explanation.

9. Who is the inventor of the VCO?

ICE77 (talk) 16:06, 10 August 2015 (UTC)

Harmonic oscillators are linear. They come from a linear second-order differential equation. Relaxation oscillators are non-linear, as it says right on the page. Gah4 (talk) 00:06, 11 April 2020 (UTC)

dither

There seems to be much editing relating to the use of dither in oscillators to reduce EMI. I added six reference showing that dither is used to reduce EMI in oscillators. Then there is the question about whether it is really dither or something else. It is the same math and physics as that in the dither article, but the examples are different. There is even discussion in talk:dither about the need for separate articles for audio dither and image dither. If it doesn't agree with dither then it is because that article needs fixing. I will see if anyone wrote in talk:dither about it. Gah4 (talk) 02:56, 25 January 2020 (UTC)

India Education Program course assignment

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The above message was substituted from {{IEP assignment}} by PrimeBOT (talk) on 19:59, 1 February 2023 (UTC)