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Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Sat, 27 Apr 2024 21:41:10 +0000 From: Joe Gwinn <joegwinn@comcast.net> Newsgroups: sci.electronics.design Subject: Re: Practical resistor accuracy distribution Date: Sat, 27 Apr 2024 17:41:10 -0400 Message-ID: <l5sq2jp8a9ntpmlc8tqdslkscrcljednh7@4ax.com> References: <v0hbbg$3us12$2@dont-email.me> <ilgo2jtvl18iqiv4t6eumqdkciu5rti2cg@4ax.com> <t2po2j9mif95u0lg1m6drskj54pf5dl27s@4ax.com> <00pq2jh2o2ru6qqlp4bs79f4bn5s95agu7@4ax.com> <ksqq2jthglli8duia5nd78scf6o0mv4nar@4ax.com> User-Agent: ForteAgent/8.00.32.1272 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 59 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-ijx+vkkzBgTboCPNA5v04JFM/vcurL75WjOZNiaOpxs7W46unt3ssE5KQjFinallazLwtrEfYDMwBFu!4JaWlZ/lCrURXaGSdhkl3vLkSafT9vjRtF/DFOoc1XToVwD3f7tGAoNh8YIJHDnltp5Vbtc= X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3227 On Sat, 27 Apr 2024 14:24:43 -0700, John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote: >On Sat, 27 Apr 2024 16:47:29 -0400, Joe Gwinn <joegwinn@comcast.net> >wrote: > >>On Fri, 26 Apr 2024 19:38:07 -0700, John Larkin >><jjSNIPlarkin@highNONOlandtechnology.com> wrote: >> >>>On Fri, 26 Apr 2024 20:16:48 -0400, Joe Gwinn <joegwinn@comcast.net> >>>wrote: >>> >>>>On Sat, 27 Apr 2024 00:54:41 +0200, Klaus Vestergaard Kragelund >>>><klauskvik@hotmail.com> wrote: >>>> >>>>>Hi >>>>> >>>>>I needed to look into distribution of accuracy of resistors. >>>>> >>>>>Vendors don't have any info, but luckily some nice people online have >>>>>done measurements: >>>>> >>>>><https://www.eevblog.com/forum/projects/smd-resistor-distributions/> >>>>> >>>>><https://lambdafox.com/resistor-tolerances/> >>>>> >>>>The thing to be aware of is that resistor value distributions are >>>>often wildly non-Gaussian. The classic example is where there are >>>>grades, say 1%, 5%, and 20%. The 5% group will often have a hole that >>>>happens to match the 1% distribution perfectly. >>>> >>>>A lot of modern resistors are made with a relatively wide >>>>distribution, and then machine-sorted into bins. In this case, many >>>>of the bins will have uniform distributions. And so on. >>>> >>>>Joe Gwinn >>> >>>I suspect that they may laser trimmed and shipped, not binned. >>> >>>One batch on a reel could be very close to one another. >> >>Also possible, and maybe a combination of both? >> >>But the fundamental point is that one must measure to be sure, unless >>one is a large enough customer that the manufacturer will simply tell >>you. >> >>Joe Gwinn > >We just assume that all 1% resistors are within 1%. > >We buy 0.1% and some 0.05% parts too. Since most of our products have >software-based calibration, we mostly care about resistor tempcos, not >so much tolerances. Yes, and calibration will wash all those strange-distribution woes away. Joe Gwinn