Ferrite Inductor Tolerance
in [Design]
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From: Joerg on 13 Jun 2010 16:23 Archimedes' Lever wrote: > On Sun, 13 Jun 2010 07:57:09 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Environmentally and financially not very friendly unless you can sell >> the excess for a reasonable price. > > 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 seems you have never dealt with the financials in production? Component culling is heavily frowned upon by CFOs and accountants, for obvious reasons. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: krw on 13 Jun 2010 16:24 On Sun, 13 Jun 2010 12:52:06 -0700, Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote: >On Sun, 13 Jun 2010 07:57:09 -0700, Joerg <invalid(a)invalid.invalid> >wrote: > >> >>Environmentally and financially not very friendly unless you can sell >>the excess for a reasonable price. > > There is nothing about coils that is bad for the environment, and I >never said anything about disposing of the remaining pieces. Making things to be thrown away is not particularly environmentally friendly, AlwaysWrong. > 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. A lot of work for no gain. Excessive manufacturing cost is not exactly environmentally friendly either. More resources... > Sorry, but most of the values will be fine, and you are wrong... >again... as usual. Nope. AlwaysWrong, that's your job here. ...and in life, apparently.
From: Joerg on 13 Jun 2010 16:24 Archimedes' Lever wrote: > On Sun, 13 Jun 2010 07:57:09 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> BlindBaby wrote: >>> On Sat, 12 Jun 2010 16:33:11 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Sat, 12 Jun 2010 15:34:24 -0700, Archimedes' Lever >>>>> <OneBigLever(a)InfiniteSeries.Org> wrote: >>>>> >>>>>> On Sat, 12 Jun 2010 15:00:59 -0700, Joerg <invalid(a)invalid.invalid> >>>>>> wrote: >>>>>> >>>>>>> You can get 5% catalog inductors from Delevan, Miller, TDK and several >>>>>>> others. If it needs to be more precise then you'd be off to boutique >>>>>>> lines, meaning $$$. >>>>>> Nobody needs to be that precise. Nobody here anyway. >>>>> We buy 2% inductors and 1% capacitors to make LC clock oscillators in >>>>> our digital delay generators. >>>>> >>>> Once you get above 100uH though prices can go through the roof. >>> Just the same... once you get up there, tight tolerance is of little >>> importance. 5% is fine. >>> >> How do you deduce that it's of little importance? Got a spy camera in >> every enterprise, worldwide? :-) >> >> >>> You want precision? You buy 500 cheap, 5% coils, and use in-house >>> matching and culling techniques to get the matched set that you desire at >>> a far far cheaper overall cost. >> >> Environmentally and financially not very friendly unless you can sell >> the excess for a reasonable price. Also, I found that when inductors >> were at minus 15%-20% then, usually, the whole series was. In fact >> sometimes over months. So no dice there, I would not sign the ECO for that. > > It woiuldn't be an ECO, you dump chump. It would be the original > design spec. Oh, and how do you suppose you get an "original design" into production without an ECO? -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 13 Jun 2010 16:26 Ian Bell wrote: > On 13/06/10 16:02, Joerg wrote: >> Ian Bell wrote: >>> On 12/06/10 23:00, Joerg wrote: >>>> Ian Bell wrote: >>>>> On 12/06/10 16:07, John Larkin wrote: >>>>>> On Sat, 12 Jun 2010 10:22:59 +0100, Ian Bell<ruffrecords(a)yahoo.com> >>>>>> wrote: >>>>>> >>>>>>> When winding modest inductors of a few hundred milliHenries on a >>>>>>> ferrite >>>>>>> core, given Al and a number of turns, what is the typical >>>>>>> tolerance on >>>>>>> the actual value of inductance when these are made in quantity? >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Ian >>>>>> >>>>>> An ungapped ferrite core could be all over the place. 25% wouldn't >>>>>> surprise me. They will vary with temperature, too. You can buy gapped >>>>>> pot cores in tolerances around 2-5%, I think. Or use a pot core >>>>>> with a >>>>>> slug adjuster if you need 1% or better. See the datasheets. >>>>>> >>>>>> Powder-type cores can be bought with better tolerances. >>>>>> >>>>>> The people who wind inductors commercially get the exact number of >>>>>> turns every time. >>>>>> >>>>>> John >>>>>> >>>>> >>>>> >>>>> It seems to me there are quite a few factors that could affect the >>>>> actual inductance achieved and perhaps the least of them is the >>>>> accuracy >>>>> in counting the number of turns. I would expect there to be some >>>>> tolerance in the Al value of the ferrite, that its exact dimensions >>>>> would have an effect along with how neatly or otherwise the turns are >>>>> wound. I have absolutely no idea if these are the major factors nor of >>>>> the likely size of the actual major factors affecting the actual >>>>> inductance. I am just trying to get a feel for the likely tolerance of >>>>> ready made inductors. >>>>> >>>>> The reason I ask is am am designing some passive audio filters and I >>>>> know exactly what tolerance of resistance and capacitance I can obtain >>>>> but not a clue about inductance. It is no good me using 1% capacitors >>>>> and resistors if inductors normally fail to achieve 5%. >>>>> >>>> >>>> You can get 5% catalog inductors from Delevan, Miller, TDK and several >>>> others. If it needs to be more precise then you'd be off to boutique >>>> lines, meaning $$$. >>>> >>>> Example: >>>> >>>> http://www.delevan.com/seriesPDFs/1782.pdf >>>> >>> >>> Those devices seem to be in the sub milliHenry range, the one I need are >>> in the humfreds of milliHenries. >>> >> >> Then you'll likely have to live with 5%, for example: >> >> http://www.yuden.co.jp/us/product/pdf/elhl_e.pdf >> >> There are other ideas but you'd have to let us know about the nature of >> the product. Things such as yearly qty, why it must be passive, how many >> inductors per unit, whether end-test trimming is ok, et cetera. >> Otehrwise it'll all be speculation. >> > > 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. > 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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: krw on 13 Jun 2010 16:29
On Sun, 13 Jun 2010 18:40:25 +0100, Ian Bell <ruffrecords(a)yahoo.com> wrote: >On 13/06/10 16:02, Joerg wrote: >> Ian Bell wrote: >>> On 12/06/10 23:00, Joerg wrote: >>>> Ian Bell wrote: >>>>> On 12/06/10 16:07, John Larkin wrote: >>>>>> On Sat, 12 Jun 2010 10:22:59 +0100, Ian Bell<ruffrecords(a)yahoo.com> >>>>>> wrote: >>>>>> >>>>>>> When winding modest inductors of a few hundred milliHenries on a >>>>>>> ferrite >>>>>>> core, given Al and a number of turns, what is the typical tolerance on >>>>>>> the actual value of inductance when these are made in quantity? >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Ian >>>>>> >>>>>> An ungapped ferrite core could be all over the place. 25% wouldn't >>>>>> surprise me. They will vary with temperature, too. You can buy gapped >>>>>> pot cores in tolerances around 2-5%, I think. Or use a pot core with a >>>>>> slug adjuster if you need 1% or better. See the datasheets. >>>>>> >>>>>> Powder-type cores can be bought with better tolerances. >>>>>> >>>>>> The people who wind inductors commercially get the exact number of >>>>>> turns every time. >>>>>> >>>>>> John >>>>>> >>>>> >>>>> >>>>> It seems to me there are quite a few factors that could affect the >>>>> actual inductance achieved and perhaps the least of them is the accuracy >>>>> in counting the number of turns. I would expect there to be some >>>>> tolerance in the Al value of the ferrite, that its exact dimensions >>>>> would have an effect along with how neatly or otherwise the turns are >>>>> wound. I have absolutely no idea if these are the major factors nor of >>>>> the likely size of the actual major factors affecting the actual >>>>> inductance. I am just trying to get a feel for the likely tolerance of >>>>> ready made inductors. >>>>> >>>>> The reason I ask is am am designing some passive audio filters and I >>>>> know exactly what tolerance of resistance and capacitance I can obtain >>>>> but not a clue about inductance. It is no good me using 1% capacitors >>>>> and resistors if inductors normally fail to achieve 5%. >>>>> >>>> >>>> You can get 5% catalog inductors from Delevan, Miller, TDK and several >>>> others. If it needs to be more precise then you'd be off to boutique >>>> lines, meaning $$$. >>>> >>>> Example: >>>> >>>> http://www.delevan.com/seriesPDFs/1782.pdf >>>> >>> >>> Those devices seem to be in the sub milliHenry range, the one I need are >>> in the humfreds of milliHenries. >>> >> >> Then you'll likely have to live with 5%, for example: >> >> http://www.yuden.co.jp/us/product/pdf/elhl_e.pdf >> >> There are other ideas but you'd have to let us know about the nature of >> the product. Things such as yearly qty, why it must be passive, how many >> inductors per unit, whether end-test trimming is ok, et cetera. >> Otehrwise it'll all be speculation. >> > >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. 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. |