do high current, high inductance inductors even exist (say 5A, 5mH)

Exactly so. To call yourself without a degree a BsEE would be misleading. Ditto for PE without a license. But EE is a job title.

You can tell that Arny isn't very bright - he hasn't killfiled poop bear.

At Saft-Nife, They used to have 10ft tall, 4ft diameter single layer coils used as loading elements. Played hell with wrist watches.

RL

He can be. He's pissed with me because I think that digital consoles are good for live sound, and he didn't at the time.

If irony killed.

Graham can be a bit pissy at time, but he is generally civil. He makes very few factual errors, and has a wide range of audio knowlege.

The world is a bigger place than parochial dumb ,Yanks think.

.......... Phil

As far as I know, switchers operating in the tens of kiloherz always use ferrites as the main inductor. Iron powder is for filters. Air core has lots of stray inductance, too lossy, also probably impractically big.

"Arny Krueger"

......... Phil

There are power op-amps on the market that can handle this sort of current easily, or a power output stage could be added to a cheaper op-amp, so a gyrator solution could be used. Depending on the frequencies involved, many quite cheap audio amplifier IC's, might be 'good enough' to work for this sort of application.

Best Wishes

I just found out what happens to a #26 care ! Not often I've seen parts smoke like that.

Useful experience though. I have some parts in #2 coming.

I looked at vishay.com and couldn't find it. Care to post a link ? It looks very small. Oh hang on - 10A Isat ? Not continuous thermally rated though is it ?

Graham

Well.... the site's own search facility didn't find it ! ( search term was 4.7uH )

I got the IHLP prefix - ( some other sizes ) - but not this series. Websites act funny sometimes.

Graham

and how, pray tell, is that useful at 5A?

Cheers Terry

except when they dont.

most iron powder cores are too lossy for SMPS applications - the trend nowadays if for fairly high frequencies and fairly large ripple currents, so large dB.

MPP and KoolMu cores are, however, extremely low loss at HF. whereas a micrometals #26 iron powder core will fry.

Vishay have a lovely range of SMT inductors, up to about 100A - eg IHLP series, 4.7uH 37mOhms Rdc, 10Adc Isat, 6.5x6.9x3mm

Cheers Terry

IME a degree proves one thing only: that the person has met at least the minimum requirement to get that piece of paper.

Many of the techs I have worked with have gone on to get engineering degrees - not because they were unskilled, mostly because they needed the paper to get the $$. It is also true to say that they didnt have the maths necessary for serious design work, but made up for it with extremely good lab skills.

IMO a large chunk of those graduating as EEs are useful for little more than viscous damping. I reckon engineers are born, not taught.

Cheers Terry

Be nice.

Cheers Terry

it depends, on 2 things:

1. Hsat - if NI is too much, the core saturates. that'll probably get you first
2. how much "no DC" there is :) Staircase saturation will eventually get you if you use approximately zero, rather than exactly zero

and lets not forget the startup behaviour, which can result in 2x peak working flux (unless it saturates, in which case it gets even worse. Boingggg)

those aside, no you dont need a gap. But you will have a lot of "fun" choosing core, turns and wire size to get L & R desired. then complicate the crap out of it by selecting a maximum volume :)

And with steel or iron powder, L will be all over the show with current.

any core, it'll also vary a lot with temperature, and no doubt sock colour too ;)

Cheers Terry

one of our techs built a 1,000A LISN. the chokes were single-layer,

Cheers Terry

I'll buy the power opamp argument (eg LM12). I dont have a java plugin running, so cant see the schematic. but what are the series resistors for 5mH? how many volts will they require at 5A? what will the losses be?

for the Antoniou inductance simulator, L = CR^2 (all identical R's).

For L = 10mH, you are going to need one hell of a large (bipolar) C for even a reasonably small R. I'm not going to analyse the thing in terms of available opamp swing etc (cant do that until know requirements of "inductor") but odds-on you're pushing s*it uphill with a pointy stick here :)

It would actually be an interesting analysis to do - at what point does an inductor "win" over an opamp. And just what do we mean by "win" - smaller? cheaper? lighter? less lossy?

Cheers Terry

I read in sci.electronics.design that Fred Bartoli wrote (in ) about 'do high current, high inductance inductors even exist (say 5A, 5mH)', on Wed, 31 Aug

Doesn't work; the viscosity would make them rise slowly, but they often rise very quickly. However, once in position, they greatly increase service tension.(;-)

"Terry Given" a écrit dans le message de news:Fk4Re.7256$ snipped-for-privacy@news.xtra.co.nz...

You mean that their main contribution will be adding viscosity to the design process?

That'll make for a nice update to the Peter's principle: In an organization each person rises to the level where the viscosity he/she adds is maximum.

I typed IHLP into the search box. Damn, I'm glad I got that tertiary education :)

Cheers Terry