For this new circuit, z=0.03975 so the pole pair is in the LHP which means the oscillations get damped out. We can calculate how long it takes to damp them out if needed.
I'm just waking up and still need to read through all the posts through the night and morning.
But, basically I agree with everything you said. It's just that now I'm questioning an assumption that I've always made previously. I generally assumed that if gain>1 sufficiently for small signals and phase is near 0, then limiting will bring the Barkhausen condition in line. But, can we be sure this will always be true? Is it possible for the limiting to cause both the gain and phase to change in a way that the Barkhausen condition in never met?
I'm surprised nobody is continuing on here because I think you can do what you want to do, and I think we are getting closer to the answers.
I thought we were done, but you seem to want to keep ignoring the nail
Look at these two Bode plots. My experience tells me which one I would choose if I was trying to build an oscillator.
Which has an unambiguous single frequency where the phase shift is zero?
Which has a single frequency where the insertion loss is at a minimum?
Well i thought we were going to try to find a circuit that does NOT oscillate yet satisfies Barkhausen? What happened to that? If we can find such a circuit we can do an analysis and find out what else is wrong.
Sorry, I'm not explaining very well. I'm mostly in a brainstorming mode here because I find this a faster way to get to answers.I dont know what you mean by gain>1 and stability. How is this so?
I also do not believe that simply stating "noise" is sufficient for start up for the following reasons:
1. If the noise does not contain the right frequency, it wont start anyway, so 'noise' is under specified.
2. If the noise does contain the right frequency, it starts, but then 'noise' is over specified.
3. Since the "right frequency" is at the heart of it, it makes more sense to simply state the the right frequency has to be present as stimulus at start up.
Winterstone's circuit appears stable for small signals and it would seem the Barkhausen condtion can be met for some particular amplitudes and conditions. Yet, the instability when the gain is limited seems to be an impediment to making a good oscillation. At small signals the circuit is stable and a signal at the right frequency can get amplified since the gain>1. So, I'm not sure how we want to classify this. Is the crude oscillations we might get with this circuit something we want to classify as a "working oscillator"?.So what this implies is that there is no real circuit that will fail Barkhausen unless the right frequency is not present, and if the right frequency is not present then many circuits will fail even though analytically they pass the two Barkhausen tests.
I agree with that.So to be specific about this other new conditions, i would state it as "having at least the right frequency stimulus present at startup" (other frequencies can of course be present too, but are not necessary but the correct one *IS* necessary). It's a necessary condition and quite succinct.
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