Update: Varistor/MOV Spice Modeling

Encrypted! Not very general.

Given how imprecise MOVs are, seems like a couple of zeners and resistors, and maybe a capacitor, would be plenty good enough.

MOVs "wear out", too. Did you include that?

To conceal my techniques. Did you read... 8 lines versus 34 ??

Parameterizable to any MOV... read!

Good enough for you, perhaps >:-}

Typical Larkin sand-in-air... you can't help but be an asshole. ...Jim Thompson

Good enough for anybody. MOVs are not precise parts.

Did I hurt your feelings by not admiring your encrypted MOV model?

I really can't imagine why anyone needs to Spice a MOV. The things that matter (power dissipation, joule capacity, wearout) aren't in the model.

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

Tim

That's LTspice's encryption scheme that adds all those extra characters. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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

Well either way, your claim is absurd, because the file size (not that 2k files are any concern these days) certainly isn't 8 lines, and without cracked encryption (anyone know if LTSpice / PSpice / HSpice encryption has been cracked? anyone working on it?), impossible to verify.

There's also the possibility that fewer lines contain more math, resulting in worse execution time or convergence anyway.

But really, I'm guessing it's your tanh fit stuff, which you've posted about publicly before. You also claim it's based on publically published curves. So hiding it is all the more absurd...

Tim

New technique. It definitely works. Try it or not, I don't care. It was originally posted to the LTspice List where the question was broached initially.

Those with interest in circuit work should subscribe to the LTspice List... you'll learn some new techniques... and not be annoyed by cockroach invasions into technical threads. ...Jim Thompson

Seems pretty pointless at your age, Jim. Are you ever going to pass on all those pearls of wisdom, or are you going to take them to the grave like King Tut?

Soon would be good, if you're ever going to.

Cheers

Phil Hobbs

Right now I'm making money at it. Why should I give away the store? Does Larkin post a _complete_ schematic of his instruments and manufacturing techniques here? ...Jim Thompson

Because you're in your mid 70s. I know your dad lived into his early

John L.'s company will probably be manufacturing stuff long after he's retired, and he isn't the sole designer, so that isn't the same case at all.

Also you vastly overestimate the opportunity cost of publishing stuff--it's usually a net win.

My book gives away the majority of what I know about what I do, and besides helping a lot of young folks (which was the point of the exercise), it has been the foundation of my consulting practice. The first edition was published when I was 40.

Cheers

Phil Hobbs

An MOV model is "the store"? That's sort of sad.

Sometimes I post actual product schematics, usually sheets relevant to the topic, and photos of real boxes and boards. Sometimes I post (non-encrypted!) Spice files. Sometimes I post ideas and scribbles that I just imagined.

I don't post manufacturing techniques, because my production people do that, and it's fairly standard stuff. I have posted a lot of breadboarding techniques, stuff that I do myself.

I don't post encrypted Spice circuits and then tell people that I'm smart, just because I say so.

I still don't know why your thing would be any better than a couple of zeners and resistors, and you won't say why.

OK. I'll divulge all my "secrets":

(1) All derivatives must exist and be continuous (2) All functions must be BOUNDED smoothly, per (1) above.

That's all there is to it other than knowing circuit design at the device level which you can pick up easily with 50 or so years or experience >:-}

Seriously.

More seriously, leukemia testing begins tomorrow.

I'll consider your advice... maybe it is time to do a load dump. ...Jim Thompson

I'm praying for good test results for you.

Cheers

Phil Hobbs

GFYU ...Jim Thompson

After you get well, you're welcome to try.

On a related note then, if anyone has something they'd like to model, I could take a crack at it.

I suspect Jim isn't doing anything I don't know, and if he sees some examples, maybe he'd even admit what it is, too ;-)

Tim

Perhaps not the right place in the thread to say this, but what problems would come up if you modelled a varistor as a behavioural current source with I = k* V^alpha in series with a bulk resistance? I've had pretty good luck with that model (just not in SPICE).

Bwahahahahahaha! I needed a laugh right now.

How about an NCP1072? That was requested on the LTspice List >:-} ...Jim Thompson

How about a resistor, diode, voltage source?

A couple in parallel if you want some curvature.

Bridge rectifier if you need bipolar.