coil impedance

I don't go out of my way to be offensive, but I don't sugar-coat my messages either. John Larkin expects to be flattered, and is offended when he isn't, to the point where he thinks he is being insulted, but this strikes me as an unusual attitude.

There's a big difference between "nothing dramatic" and "this book should be burned" or whatever it was you said in another post. What exactly is wrong with the book which should be burned? Apart from the asking price, which I wouldn't pay, but I might do the equivalent of having a quick look through the book before putting it back on the bookstore shelf.

As much as you design anything. The thermal contact pad under the coil that keep it from getting too hot was presumably optimised by the same kind of well-thought-out rigorous process.

Measuring the internal diameter with vernier calipers could give you a more easily archived reference.

Somebody more image-conscious might have machined (or 3D printed) a metal helix to more precisely specified dimensions. Something a bit bigger might have been easier to cool.

"Bill Sloman" snipped-for-privacy@ieee.org wrote in message news:10emofm$2cnh3$ snipped-for-privacy@dont-email.me...

You don't seem to be interested in providing information which would lead to better products Bill. You seem to be much more interested in telling other people how stupid they are for only designing products which are "quite good enough".

The circuit below is not good enough in my view but you didn't seem to be able to handle any criticism of it some time ago.

What are Audiophiles going to think when they have to wait a whole second for the output level to stabilize? Not to mention the barely 60dB harmonic performance. These factors show that it is not well designed.

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100n SYMBOL cap 832 -2080 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C15 SYMATTR Value 100n SYMBOL cap 880 -704 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C16 SYMATTR Value 100n SYMBOL FerriteBead 2208 -2144 R0 SYMATTR InstName L1 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap 2288 -2080 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C7 SYMATTR Value 100n SYMBOL OpAmps\\LT1679 -624 -1472 R0 SYMATTR InstName U3 SYMBOL OpAmps\\LT1679 -176 -1520 R0 SYMATTR InstName U8 TEXT -1704 -504 Left 2 !.MODEL BAS70L D IS = 3.22E-9 N = 1.018 BV = 77 IBV = 1.67E-7 RS = 20.89 CJO = 1.608E-12 VJ = 0.3891 M =

Here's a rewrite of your reply below which would make me think you're being very helpful instead of being a complete moron.

How did you make sure that the thermal contact pad under the coil will keep the coil sufficiently cool?

Have you tried measuring the internal diameter with vernier calipers? This could give you a more easily archived reference.

Have you considered machining (or 3D printing) a metal helix to more precisely specified dimensions. Something a bit bigger might have been easier to cool.

You obsess over JL and DT. I'm in good company.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

I don't think that you approve of engineering.

Thermal conductivity of the pad and an estimate of contact area. I wrote a program that helps with such thermal calculations.

There a lot of vias through the board to pipe heat from the inductor down into the baseplate. That adds theta too.

One of those gigantic multiphysics programs would be better, but I don't have one. It wouldn't be worth the effort to estimate coil temperature a few degrees better.

The gap-pads are at best around 7 w/m-K, and one can doubt their data sheets too. Pad theta is a strong function of compression, even more

But the Pockels Cell driver works and is a few per cent of the volume of coventional MHz-KV designs.

How would you design such an inductor? Or such a pulser?

Size affects inductance!

The customer hasn't complained.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

That’s amazing. Over a microhenry, and no short-time capacitive dip, even on the 50-ps timescale.

Definitely a keeper!

I’ve been using multi-bank Litz wire induction coils for VLF, and discovered a very low noise (< 500 mK at room temperature) damping scheme that knocks down the Q=400 first resonance down to Q<0.7.

It only works on the first resonance, because the higher ones are less strongly coupled with the ends of the coil, and have an irreducible time delay.

Cheers

Phil Hobbs

I assumed that this was an old technique that nobody remembered, and found only one related patent: US 2,787,704 to Willem Wigger Boeiens and Jan Willem Tap of Philips.

Cheers

Phil Hobbs

It's easy to kill resonances, if you don't care much about Johnson noise.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Edward Rawde's ides about which of my arguments might be nonsense do seem to be idiosyncratic.

Being 82 doesn't help.

I've not seen any indication that anybody ever has. And I doubt if they would have the effect he imagines. My CV has always listed my published critical comments in peer-reviewed journals - ten of the 13 publications I list - while I've not had anybody comment on them in an interview, one correspondent once said he thought that one of my comments was more informative than the - admittedly dire - paper I was commenting on.

This might be clear to Edward Rawde, but it doesn't happen to be true. In fact it is an absurd misrepresentation. In reality I spent quite a bit if my professional career supervising and directing junior engineers, and that does involve telling people that they have got stuff wrong and showing them how they can get it right. That's never painless but I could do it without making people hostile.

Most words have remarkably precise meanings (but that may depend on the context), and educated people know what they are. My wife was a remarkably high=powered specialist in human speech production and perception, and could spell out the evidence at length if you gave her the opportunity. Most phsycholinguists will, if you give them half a chance.

So you aren't completely crazy.

You need precise language to spell out what the mathematical description applies to.

I'd need access to a lot more information than I can find on-line to construct such a mathematical argument. And I haven't been arguing that other people can't design ferrite cored or other inductors very well. The problem is more dealing with the stray capacitances associated with the windings, and when John Larkin doesn't put them into his posted Spice models I've got all the evidence I need.

Edward Rawde does seem to project his own motivations onto other people. I do take pleasure in constructing a concise argument. I am less interested in the emotional reaction it will illicit. I know that John Larkin likes to be flattered, but I can't be bothered going to the trouble of shaping my comments on his posts into anything that might look flattering.

That is the 2010 second edition

So is E.C.Snelling's pile of nonsense. Publishers publish rubbish like that because they can rely on selling a few thousand to university libraries. even if nobody is going to bother to read them

Edward Rawde's idea of rigor is going to be just as idiosyncratic and self-serving as his other ideas.

That was E.C.Snellings book on "Soft Ferrites". It was a largely incoherent collection of detailed data, so poorly organised that I found it very difficult to find what I needed. If anything, exposure to the book left me more confused about the subject than I had been before dipped into it. Reading it from cover to cover would have been pointless.

You think that Donald Trump is good company? Jeffrey Epstein did too.

Since it comes from the early part of a very long thread, and since I subsequently posted variations which performed a whole lot better, I seem to have been able to handle well-informed criticism pretty well.

JM was a whole lot more helpful than you were.You did post a variation of one of his circuits which managed to use eight transistors in the adjustable gain section - which he promptly cut down to four, and I subsequently increased to five which got us up to 150db suppression of the higher harmonics

They won't care. It is a reference sine wave generator.

The design did need improvement, and it got it. I'd posted it as a first try at an alternative to the FET gain control element. 60dB harmonic suppression is actually pretty good, but the FET approach could do much better. JM changed my design to get it to do much better. You didn't like his tantalum bead capacitors and found another way of reducing ripple feed-through, which he was able to simplify.

Oh, I do, but I don't think that what you do qualifies as engineering. Desperate improvisation comes closer to the mark.

You need to write a program to calculate that?

They just conduct heat. Heat pipes rely on evaporation and vapour transport, and can have a much lower thermal resistance, if you have the space to squeeze one in.

Then the manufacturer makes a slight change in the way they make their thermal pads, and you have to do it all again.

I'd find out what the Pockels cell needed, and go from there. Sometimes you can reorganise the parts that are being driven to make them easier to drive.

So does number of turns.

So it is good enough. Not necessarily as good as it might have been. Engineering has been defined as doing for one dollar what any damned fool could do for two.

Low volume niche markets rarely justify that kind of optimisation.

The press conference in this week in the Oral Office did put the icing on the cake, when one of his minions fainted.

He was the only one in in the room who did not care, let alone try to be helpful. He just turned away, his face saying "This is MY press conference! Can't you go elsewhere to die?!!! Scumbag.

So far for "good company".

Gerhard

That's electroplated silver coatings, and that fell out a favour a few years ago when it was realised that an electroplated layer of silver doesn't have the conductivity of solid silver, or even solid copper.

Someday somebody may used a pulsed laser to melt just the top micron of an electroplated silver layer, but it doesn't seem to have happened yet.

I can think of no reason why you would ever have seen any such indication. Any more than I can see which web pages you visit.

You must have lost that ability somewhere along the way.

Er when Liz said "I worked for a company that built its reputation on the R.F. inductors it designed; these factors were among the many problems they tackled."

Your reply was "Probably not very well."

So either we have an issue with the meaning of words or you're talking nonsense.

So why haven't you written and published your own book which is not a pile of nonsense?

That doesn't sound like a reason for burning it to me.