Twin T circuit wanted

John gazes into the mirror (guffaw) and details for us his... err... our dilemma.

Yeah... sure... bub.

1 volt. That might be a bit hot, as I noted in the post. I did that on purpose, thinking a smaller conduction angle would give better frequency stability. You know, let the L-C ring unmolested as much as possible? Might not be helpful though--if the drive is sine-ish, the tendency to pull might not apply. Not sure.

Yes, class-C.

I like the schottky. Takes trr(b-c) out of the equation.

James

I prefer smaller drive, a tenth or so p-p on the emitter. Maybe even less, basically class A.

The whole thing behaves differently if the secondary drive is large and the transistor conduction angle is small: the emitter voltage will swing down, way below ground, and pull the base down with it before the collector voltage gets down to ground... blasting a spike of collector current into the tank. Then it will swing way up and turn the base off. Brutality! Chaos!

I prefer a more delicate touch: the collector dips down elegantly, like a swan landing on a pond. It just barely touches the water, err, emitter, and together they remove a bit of charge from the base cap. And then it flies away. Did I mention the sunset in the background?

John

20mV

--^^^^^^

Ooops. That was for another sim, which uses 1mH and 10uH. The posted

5 KHz ckt used 1mH / 25uH, so the emitter swing was about 1.8v p-p.

James Arthur

Not at all. Cripes, can you imagine what would have happened if Rutherford had gotten all offended when meeting with his young students who might have proposed some idea? I had loved reading, somewhere, that he would listen to any and all if they thought they had _any_ idea, no matter how modest or odd it may have been. They would take a break every afternoon for tea, cake and buttered bread and just sit on stools talking. Nice. 11 of his students went on to receive Nobel Prizes, not to mention some of the collatborators who also attended and also won Nobels. Not that I think what I wrote is anything much. I'm just saying...

I do have a copy and have carefully read the first 5 or 6 chapters of the first book, only. I have not read chapter

I'll read it, tonight. Though I may need to _also_ go back and read on polarization to refresh that, as well.

It's the way I imagine it and it works to solve any questions I've had about the concepts others teach differently (and to me with less clarity.) I am sure, someday, there will be some behavior that requires me to modify it. But so far for my limited experience, it works well. I like it better because I don't have to think about how recoverable EM energy (which in my imagination can ONLY be stored in a vacuum) might be one figure for vacuum, another figure for atom A, another figure for aligned atom A, another figure for atom A in an excited state, and so on. I just have to keep one thing in mind... energy is stored in vacuum, only, and permeability is simply a fudge factor used to estimate the effective ratio of the vacuum path length and the vacuum path length less the magnetic short circuit length (once alignable atoms are aligned.) L_vacuum / (L_vacuum - L_shorted). It's a fictitious parameterization so that we humans can use basic measuring tools and simple observations plus that figure to estimate the effective vaccum psth length remaining for energy storage. But the recoverable energy really only goes into vacuum, I believe.

Which makes complete sense. I mentioned before that I also imagine aligning the atoms takes energy, but it isn't recoverable. The work involved in aligning is largely ('all' probably, unless there is a wound up spring recoil effect which I don't at all imagine exists) converted to heat. If you reverse the alignments, you do more work. And so on. But you don't get it back. That goes into heat.

It's only the energy stored in vacuum (energy cannot be created or destroyed) where there is no possibility of "heat" that you can recover. (Would be interesting to imagine the case where you could actually lose energy as work converted to heat in a vacuum... hmm... could you cause the vacuum to heat up enough to create 'vacuum ash?' Enough letting my imagination get away with me... ;)

Jon

I should add that the way I imagine re-aligning taking place is with each atom as little aligned gyroscopes. When a force is imposed on them to alter their orientation, they twist in the field and this twist bumps them against others also being turned and this results in some of the energy going into lattice/material vibrations that amount to 'heat' in the end. I'm not sure how to make that quantifiable, except that if that imagination has any predictive value, it would suggest that very fast changes would cause a great deal of heat as the little gyros would twist quite strongly then.

Jon

Point away from the bit you want to see and zoom out. (or use the scroll bars)

--- news://freenews.netfront.net/ - complaints: snipped-for-privacy@netfront.net ---

--
Why imagine?

Here's a circuit list that'll show it all _and_ it'll create a .wav
file, "bong.wav" in whatever folder the cicuit's in, so you can hear
it.

Enjoy! :-)

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Me?

Go do it yourself Jim.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

--
Perhaps not in so many words, but your neverending patting yourself on
the back while demeaning the work of others speaks volumes about what
you perceive yourself to be.

--
Typical Larkinese tactic; poisoning the well.

Better watch out, Win, if you disagree with him he'll more than likely
have something nasty and untrue to say about you, too.

--
Yup, and just about everything else in the world.

JF

--
Unfortunately, you'll probably never get the asshole to own up to it,
being that to this day he still maintains that latching relays have
infinite gain.

--
Unbelievable!!!

You hoist yourself on your own petard and you don't even know it.

On Fri, 11 Jun 2010 07:02:03 -0500, John Fields wrote:

--- Oops... Here it is:

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I like the way it works with a very high turns ratio, very small AC drive at the emitter. But at lower ratios, it gets very nonlinear and becomes, if that means anything, a tuned blocking oscillator. The base capacitor value would be lowered so that the cap recharges a bunch during a oscillatory cycle.

I'm sure JT and JF will spend the next week diligently searching for a set of values that will make my circuit not work. Then they'll crow, or rather, cluck about it. That's OK: as Woody Allen says, we need the eggs.

John

Tell us why tuning fork oscillators are amplitude stable.

And why my circuit won't oscillate.

John

I have two copies of his book, one at work and one at home, and I give one to every intern who doesn't already have one. I've learned a lot from his book and his occasional postings (is 3e done yet?) and I'm happy to discuss circuits with him. "Discuss" means just that, play with ideas, diverge and converge, brainstorm, tell stories, get stupid, evolve things. Try it some time: it's fun.

Some people can play this game, some can't.

John

Can you quantify that? Round off the the nearest millisecond.

John