Ferrite Inductor Tolerance

Fractional Henry, yes. I never said I wanted 1%, I just wanted to know what is the likely tolerance. Q or more than one is easy with inductors even of several Henries.

Cheers

Ian

Thanks for the input but I think you have misunderstood me. I already have a source of suitable inductors. What I am interested in is the factors that govern the tolerance of a production inductor (as it comes off the line and before any selection process) and what the resultant overall tolerance is likely to be for inductors around 1H. I am not asking for help designing a product or in selecting parts.

Cheers

Ian

Then why don't you ask them?

Of course, one problem with inductors is that L tends to vary with frequency, so what they measure and what you measure may not be the same.

John

I've done audio-range, fractional-H filter inductors as BIG pot cores, with decent Qs. Never again. I don't think I'd do a signal-processing LC filter below maybe 1 MHz nowadays.

John

I did use 1% inductors in "power" (was 50mW level) application a few months ago.

Now, let Alwayswrong bitch...

True. The 2% parts we use are 1008 wire-on-ceramic things, 150 nH sort of stuff. Like most "air" core inductors, they have a positive TC in the 120 PPM ballpark. We do coarse compensation with NTC caps, fine with a temperature sensor, software, DAC, and a varicap.

It's hard to buy surface-mount NTC caps in reasonable quantities.

John

There is nothing about coils that is bad for the environment, and I never said anything about disposing of the remaining pieces.

The matching and culling also allows one to use an off target value, as long as value matching is used, and the balance can be set by adjusting the cap values if that is even needed.

Sorry, but most of the values will be fine, and you are wrong... again... as usual.

It woiuldn't be an ECO, you dump chump. It would be the original design spec.

Look up ANY typical parameters and see that there is so much slop aging, and drift in so many of them that your desired 'batch' of inductors would be hard to gather up.

That is why a lot of such a custom value will be a 5x cost increase or more over normal product runs.

Were they >100mH, like the OP speaks of?

It seems you have never dealt with the financials in production? Component culling is heavily frowned upon by CFOs and accountants, for obvious reasons.

Making things to be thrown away is not particularly environmentally friendly, AlwaysWrong.

A lot of work for no gain. Excessive manufacturing cost is not exactly environmentally friendly either. More resources...

Nope. AlwaysWrong, that's your job here. ...and in life, apparently.

Oh, and how do you suppose you get an "original design" into production without an ECO?

Having designed several custom inductors and transformers, the largest tolerance contribution came from the core material. Not the dimensions, those are very precise, but from the materials properties.

I've found that manufacturers for highish L (1-5H), small, transformers seem to have a hard time holding the permeability to -50%. After that, 5% DCR tolerance seems to be about the norm.

Form the leads of the beaded style into 'stands' for surface mounting. Yes, it then becomes a hand installed part.

Same way we used to 'surface mount' axial leaded glass diodes before the little barrel SMDs came out.

It seems that you have never dealt with the electronics industry for the last 50 years.

Matching and culling was REQUIRED in many instances due to so many variables that were around back then. You have no clue. You also have no clue as to how such needs and tasks (and designs) were optimized to minimize losses.

In other words, Shut The Fuck Up, idiot.

Read it again, and show me where I said anything about disposal of anything at any time.

You are a retard, and an ass.

You must also be an acronymical retard as well.

There is a difference between a design release and a change order of an existing design.

Go away, you clueless bitch.