Precision Resistors - General Thread - Page 1
Forum section: electronics / general

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: July 03, 2021, 08:53:26 pm
content: Hello Everyone,Let's talk about precision resistors! This is an open invitation for members to contribute to a list of resistor sources and provide a discussion about their own experiences with resistors.- manufacturers- series/models- specifications- types- applicationsSeeing as there is interest in building environmental test enclosureshttps://www.eevblog.com/forum/metrology/diy-large-thermal-chamber-for-metrology-tm-testing/?all, maybe we can also combine our efforts to measure their performance specifications to either confirm or disprove claims made by the manufacturers. Personally, I am very interested in confirming voltage and temperature coefficients. My Advantest R6581T is being sent to the TransCat calibration centre in Texas, so it might be a while before I can contribute to that venture...So far, I have collected a list of my own (MegaOhms to TeraOhms range) and maybe we can combine our knowledge to benefit the community. Here is a link to my Google Sheets work-in-progress:https://docs.google.com/spreadsheets/d/1HSdXGIUwK_Is3uJIlgVGw9Qx-jLj2GVnV8qsp52-f8w/edit?usp=sharingEDIT: The above spreadsheet outlines the best-known commercial resistors that I am aware of for a specific decade. The original intention of the spreadsheet was to help me decide on resistors for a precision decade box.I have made the document viewable and you can comment on details if I have made mistakes or you want something else included.Preferably, one should discuss and comment at the EEVBlog so that the information is accessible.Looking forward to your responses!That's it for now.

author: TiN
author_rank: Super Contributor
timestamp: July 03, 2021, 10:14:24 pm
content: Good idea to start with methodology, on how we represent temperature and voltage coefficient. It is common piece of specmanship from vendors as they can use generic word "temperature coefficient" while showing only specific typical data or showing "averaged" tempco out of large resistor lot, rather than more difficult guaranteed maximum specification.I often test resistors and parts in smaller chamber with slooow and smooth temperature ramp from low to high temperature and back. Doing it in cyclic manner help to reveals possible hysteresis issues (often common aspect of physically larger resistors and wirewound resistors). Temperature range I commonly run is 18-50C to include metrology grade 18-28C range and wider common PCBA temperature.My dataset from few years back, based on collected and measured resistors is already published on my site, but these articles cry for major overhaul...I also tested hundreds more resistors since then.https://xdevs.com/article/tcr_test/https://xdevs.com/article/caddock_news/I also tried combining multiple 1 Ohm resistors into one combined resistor but failed miserably due to large error from copper wiring TCR.https://xdevs.com/article/1r_tests/Also bonus, little Fluke 742A factory speclist database and minor repair of few 742A I had hands on here :https://xdevs.com/article/f742a/.

author: veedub565
author_rank: Frequent Contributor
timestamp: July 06, 2021, 12:59:07 pm
content: Maybe a little OT but I'd be interested to hear peoples thoughts on this source of lab standard precision resistorshttps://www.ebay.co.uk/itm/331951651645?hash=item4d49dc3b3d:g:VUwAAOSwLfNa2EXb

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: July 07, 2021, 12:39:50 pm
content: Quote from: veedub565 on July 06, 2021, 12:59:07 pmYou could also tryhttps://www.eevblog.com/forum/metrology/teardown-standard-resistors/?all.

author: veedub565
author_rank: Frequent Contributor
timestamp: July 09, 2021, 09:15:08 am
content: Thanks for the link, there is a lot of detailed information in that thread.

author: manganin
author_rank: Regular Contributor
timestamp: July 09, 2021, 09:51:57 am
content: Quote from: veedub565 on July 06, 2021, 12:59:07 pmThose Krasnodar type standard resistors can be very good, but the quality varies a lot. You may need to buy ten to get one decent. And in real life the seal is far from hermetic, so nowadays it is hard to find anything not ruined by bad storage.The primary resistor set of the Estonian national laboratory used to be Krasnodar, but that was at least ten years ago and they may have upgraded. Of course the examples found in high level labs are carefully selected.

author: Grandchuck
author_rank: Super Contributor
timestamp: July 13, 2021, 07:40:29 pm
content: Here is my reference resistor for the 3458A DMM and other applications. It is mounted in a Bud Industries enclosure and uses a Vishay VHP101T metal foil resistor. I would like to have it calibrated without spending a lot.

author: TiN
author_rank: Super Contributor
timestamp: July 13, 2021, 11:27:39 pm
content: Send it over, I can do +/-0.4ppm uncertainty for you on it

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 14, 2021, 10:30:08 am
content: Quote from: Grandchuck on July 13, 2021, 07:40:29 pmHello Grandchuck,you have a solid 4W Kelvin connection, the case has a seal and it provides some thermal mass, but your assembly is lacking a proper thermal connection between the resistor and the case. And it's lacking a stable/precise thermometer, to first determine the T.C., and afterwards mathematically compensate the resistance value for its own T.C., compare the setup of the SR104.Without that, it makes no sense to calibrate it to a certain value, because the T.C. might be as high as 0.3ppm/K (acc. to the datasheet of the VHP101).If Illya offers 0.4ppm uncertainty, I would strongly suggest a proper setup first.Frank

author: manganin
author_rank: Regular Contributor
timestamp: July 14, 2021, 11:59:19 am
content: My suggestion would be fill the box with styrofoam with a small space in the middle for the resistor and a thermistor. (Check the insulation resistance of the material chosen of course.)The idea is to make the thermal time constant from the outside world to the resistor as long as possible. Two advantages:1. temperature stays steady during measurement2. protects the resistor from temperature extremes during transport or at least makes the rate of change less violent.

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 14, 2021, 02:44:44 pm
content: Quote from: manganin on July 14, 2021, 11:59:19 amHi, in this case it's much better to have a big thermal mass (aluminium or oil filled cavity) to stabilize / slow down temperature changes.Isolation with styrofoam is usually done on self heated applications, like in OCXOs.The thermometer and the resistor have to be tightly coupled, e.g. assemble them in the same aluminum block.If you ship such a standard ( Ohm, Volt) over several days in cold weather, a styrofoam isolation does not really help, it just looks as if it would protect from excessive cooling down, but in reality it doesn't. We already made our experiences with "cold" shipped LTZ1000 inside a big isolation package, and they simply shifted anyhow.Only way around is to monitor the shipment temperature inside the package to find out if the temperature fell below a certain critical threshold (+15°C in this case), or to ship the standard "hot", or to invent a rejuvenation process, to mitigate possible hysteresis shifts (similar to the Fluke 7000 voltage standard).The bulk metal foil technology also shows hysteresis on big temperature changes. Don't know how much this is on the VHP101 chip, but the Z foil technolgy (VHP202Z) which I use, showed +5ppm on a -40°C trip. I could remove that hysterisis by thermal cycling.Precision wire wound is much better in this aspect.Frank

author: Kleinstein
author_rank: Super Contributor
timestamp: July 14, 2021, 04:17:53 pm
content: +1 to adding thermal mass. Part of this could be some silica gel, to also get a stable humidity. It is not that important with a hermetic resistor, but the temperature sensor may not be hermetic.For the 4 wire connection there is no need to have very low resistance from the drive to the sense terminals it is more like aiming for a defined point where the 3 connections to the terminals and resistor meat. With a 10 K resistor this is not that important though. So the design looks a bit sloppy but is OK for 10 K, but would be a problem for 10 Ohms.

author: TiN
author_rank: Super Contributor
timestamp: July 14, 2021, 05:40:18 pm
content: +2 to thermal mass and temp sensor.

author: TimFox
author_rank: Super Contributor
timestamp: July 14, 2021, 06:09:32 pm
content: To Grandchuck:Is there a reason why you soldered the resistor wire leads to the bars, rather than clamp them to the bars with additional screws?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: July 14, 2021, 06:11:23 pm
content: Quote from: Grandchuck on July 13, 2021, 07:40:29 pmHi Grandchuck,Can you be more specific about what you mean by a 'reference resistor'? Is this simply to periodically track the measurement drift of the 8.5-digit DMM over time to ensure it does not fall out of tolerance?If drift monitoring is the case, then one should ensure that the drift from the resistor is significantly lower than the instrument so that the drift is representative. A calibrated resistor will not be important for this task but calibration would be necessary as a transfer standard.Edwin Pettis sent me a link to a recent post he made about resistor terminology that may interest you.https://www.eevblog.com/forum/metrology/precision-resistor-specifications-and-definitions/msg1557151/#msg1557151Have you made any resistance measurements with your 3458A over time and compared them with the specifications of the instrument?Apologies for yet another round of criticism, but what is your reasoning behind the black washer underneath the nut and metal washer? If this is a permanent test fixture, why not purchase a 4-wire resistor and directly solder the leads onto the binding posts after wrapping them around the posts a few times?For resistor box designs, I personally enjoy how zlymex has made his resistor box with dual shielding and I may borrow some of his ideas when I receive a VHA518-11Z (Y4773310K0000S4L) later this year. He is using VHP101 Series resistors like you and has claimed to have excellent low drift results (see enclosure labels).https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg892700/#msg892700My Advantest R6581T has been sent to Texas by TRANSCAT for calibration. This amateur is leaving it up to the experts. Once I have an accredited instrument (adjustment with data and uncertainties), I plan on calibrating the rest of my test gear with it.If you want a reliable resistance transfer standard, you could consider:http://www.ohm-labs.com/resistance-standards/index.htmlhttp://lowthermal.com/resistance-standards.phphttps://guildline.com/primary-electrical-metrology/resistance-standards/precision-dc-air-standard-resistorshttps://www.ab-precision.de/products/electrical-standards/(ask if it is appropriate for an 8.5-digit DMM)https://us.flukecal.com/products/electrical-calibration/electrical-standardshttps://www.ietlabs.com/esi-sr1-calibration-resistor.htmlPersonally, I would look at the teardowns before investing ~2000 USD though.https://www.eevblog.com/forum/metrology/teardown-standard-resistors/?allRegards.

author: Grandchuck
author_rank: Super Contributor
timestamp: July 14, 2021, 06:42:40 pm
content: I am going to mount a solid chunk of aluminum in the bottom of the case (see photo). What should be used to insure thermal conduction? Is heat sink compound OK?Do you recommend attaching a heat sensor to the aluminum chunk? Is a thermistor OK?A quick (crude) first measurement yields a negative temperature coefficient of about 0.15 ppm per degree C. I will be making more careful measurements.I soldered the resistor because it was easy. How much trouble will this cause? I used heat sinks on the leads, by the way.The black washers are lock washers. They were supplied with the banana jack assemblies.I have been mostly Volt-nutting and felt the need to try Ohms for a while. Also, having something available in the way of a resistance standard seemed like good idea.I have several 10 volt references that I feel reasonably good about, so I guess this is the next step. Having fun, in any case, and learning too!TiN: that is soooooooooo generous of you. Might take you up on it!Big thank you to all who posted.

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 14, 2021, 09:31:24 pm
content: Quote from: Grandchuck on July 14, 2021, 06:42:40 pmHi Grandchuck,we already had a similar thread like this one, and there's my assembly, showing how the VHP, precision thermistor and case are all thermally connected together.Most important is, that the NTC and the VHP are closely assembled into holes of the aluminium block. Yes, I simply used thermal grease for that purpose.The oil fill of the VHP resistors gives a very good thermal conductivity between the resistive element and its case.The lower the T.C., the less important is the accuracy of the temperature. Anyhow, the sensor needs to be stable over time only, as the absolute temperature does not play a role, only the initially measured relation between the resistance of the VHP and the temperature as given by the NTC.Only with such a solid assembly, one will be able to make repeatable measurements of R(T) and T.C.https://www.eevblog.com/forum/metrology/t-c-measurements-on-precision-resistors/msg464413/#msg464413Frank

author: dietert1
author_rank: Super Contributor
timestamp: July 15, 2021, 05:05:46 pm
content: Not completely true.I have been using a SR1010 (12x 1KOhm) with its wirewound resistors hanging free from the connector panel and a built-in temperature probe (PT1000) glued onto the inside of the connector panel and was able to characterize its TC to be 1.84 ppm/K with great precision, see here:https://www.eevblog.com/forum/metrology/esi-resitance-standard-sr1010-and-standard-resistor-sr104/msg2719638/#msg2719638.This is the same SR1010 i brought to the metrology meeting in 2019 where we reproduced its original calibration from 1969 within one ppm or so. In the SR1010 the deviations by self heating that Mr. Frank is talking about, are small due to the size of the wirewound resistors. No solid aluminium blocks.Regards, Dieter

author: Grandchuck
author_rank: Super Contributor
timestamp: July 23, 2021, 06:59:59 pm
content: Finished the reference resistor. It measured -0.5 ppm/degree C over a range from 16 C to 25 C. Picture and thermistor characteristic curve attached. Thanks again for the help!

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 07, 2021, 12:42:02 am
content: Anyone else noticing a massive shortage of precision components as of late? A resistor order I had scheduled this month is now set for November 21st. Some of my other orders are now saying next year. There doesn't seem to be any stock.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 08, 2021, 09:52:58 pm
content: I just wanted to point out that Vishay sells secondary resistance standards with NIST traceable certificates:http://www.vishaypg.com/docs/63223/fsr.pdfThey even offer custom resistance values.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: August 08, 2021, 10:31:34 pm
content: These are also available from Texas Componentshttp://webdirect.texascomponents.com/searchresults.asp?cat=1839

author: mendip_discovery
author_rank: Super Contributor
timestamp: August 09, 2021, 08:51:43 am
content: Out of curiosity what oil would be the best for submerging the resistors?I have a couple of resistors here at home that I planned to make into a crude resistance box, some being low ohm ones. Nothing posh but more of an exercise in learning more about it but making mistakes so I can avoid them in the future. Plus I have several bits of kit at work that does get some use and I would like to make some spares.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 10, 2021, 12:14:59 pm
content: Quote from: mendip_discovery on August 09, 2021, 08:51:43 amMineral oil is used for the submersion of oil resistors.Usually, you can find this information in a datasheet or manual for oil bath products. For example, Guildline makes a 5600 Series fluid bath (https://guildline.com/temperature-metrology/environmental-control/air-and-fluid-baths/5600-series-high-precision-variable-temperature-fluid-baths) and the manual (https://guildline.com/media/k2/attachments/OM5600-E1-00.pdf) states the following:6.1.1. Model 5600 Oil Recommendation:There are a number of different metrology grade mineral oils, from various manufacturers, that are suitable for a Guildline oil bath. The key specifications are:Density at 15 Celsius, kg/m cubed = 850Color, Saybolt = +30Kinematic Viscosity, Cct@40 Celsius = 12.8The original oil recommended and used by Guildline for oil baths was Marcol 72 or Marcol 7. However, this oil is no longer manufactured.Guildline now uses Total Nevastane Clear 15 White Mineral Oil. It is manufactured in Canada by Total Lubricants in Laval Quebec.Other equivalent oils, with their supplier, are:Petro-Canada - WO10Sonneborn - Carnation White Mineral OilPenreco - Drakeol 7 and Parol 70Whitaker Oil - 70 White Oil USPThere is also Total Finavestan A80B oil which has a slightly higher viscosity than we recommend but its use should not affect stability of a Guildline oil or fluid bath by more than 1 mK.---This is clearly a Canadian company that lists products from my country, there might be other options where you are from.I hope this helps.

author: TiN
author_rank: Super Contributor
timestamp: August 11, 2021, 01:08:27 am
content: Higher resistance values and setups also can use silicon-based oil, which provides higher resistance insulation and more chemically stable (also more expensive).

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: August 11, 2021, 02:55:45 am
content: I came across this document from IET in regards to the oil filled SR-1030 series. Chapter 6 talks about their recommended oil and how to test if it is contaminated enough to warrant doing an oil change.https://www.ietlabs.com/pdf/Manuals/SR1030_im.pdf

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 12, 2021, 06:29:12 pm
content: Quote from: leighcorrigall on July 03, 2021, 08:53:26 pmAll those clues makes it clear to me, that this conversation will not deliver anything useful regardingmodernproducts and solutions.Few years agoVISHAYaccepted to collaborate with me about the promotion (due my Blog) of their latestHermetically sealed Vishay Foil Resistorsthe ones dedicated for calibration.Because of that receivedYES from VISHAY, I did challengedHIOKI Japan, about me getting a sample of their finest resistor meter, which out to be aware that VISHAY was all ready a HIOKI customer, and that the specific instrument (of my choice as sample), it was in use all ready from Vishay at Israel, in their production lines asTHE inspecting deviceof new resistors production.According the measurements of the HIOKI (self calibrated meter), the new products are labeled and shipped to the customer.The measurement of the HIOKI resistance meter, does not change, no matter of the room temperature that could be 12C ~ 35C, when the DUT is one of those Hermetically sealed Vishay Foil Resistors.For three years I was trying to document changes of temperature coefficient of my resistance samples, and this was not possible because resistance does not change at within planet temperature range.An benchtop DMM will never be equal to dedicated and modern resistance meter.In conclusion, two brands hold in their hands the present and future of our precision resistors.Best third or fourth or fifth measurement device, this is unimportant when the target this is precision resistorsproduction.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 12, 2021, 06:57:06 pm
content: Quote from: ITTSB.Europe on August 12, 2021, 06:29:12 pmFair enough. Vishay is out of my measuring capabilities.EDIT: Not everyone uses Vishay resistors for every application.The point here is to form a discussion about resistor products manufactured by a variety of companies. Each resistor company, model, make, is going to have its differences. Maybe it will be beneficial if there is a general thread for people to read about them and make decisions on what resistors to buy for their design.To clarify, the DMM is being calibrated so that I can check my other equipment is within specifications before I conduct measurements. My plan is to determine whether the purchased resistors (a sample set) are within the specifications outlined by the manufacturers. This should be possible with enough contributions from other members to form a statistical outcome. Provided that enough people contribute, we might be able to help each other determine skew points too.Most of the resistors that I have are greater than 1 MΩ. Thus, VCR and TCR should be measurable in this range for me considering I have a high-voltage source, a decent DMM, and a precision temperature control environment.I will leave the low resistance measurements to people with the capabilities.You sound like you might have decent equipment. Would you like to contribute?

author: alm
author_rank: Super Contributor
timestamp: August 12, 2021, 08:27:55 pm
content: Quote from: ITTSB.Europe on August 12, 2021, 06:29:12 pmWhat model is this meter? Do you have a link? Datasheet?Quote from: ITTSB.Europe on August 12, 2021, 06:29:12 pmWhat is the long term accuracy? Transfer accuracy? Temperature coefficient? Is this awesome stability because of the bridge, or because of the reference resistor?Quote from: ITTSB.Europe on August 12, 2021, 06:29:12 pmSo how does this mythical instrument that apparently has no equal in the world work? A direct current comparator bridge like those made by Measurement International for lowish resistance values? A Wheatstone bridge as might be used be used for high resistance values? Or just a more fancy constant current source + voltmeter (or constant voltage + ammeter) setup?

author: Echo88
author_rank: Frequent Contributor
timestamp: August 12, 2021, 08:52:05 pm
content: https://www.ittsb.eu/"Reviews of ONLY THE BEST !! Tools for truly experienced and productive human brains."Im sure its this one:https://www.ittsb.eu/Ultra-High-Precision-resistors-Box.html#RM3542ARM3542A-datasheethttps://www.hioki.com/download/33016"In conclusion, two brands hold in their hands the present and future of our precision resistors."

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 12, 2021, 08:54:52 pm
content: Quote from: alm on August 12, 2021, 08:27:55 pmITTSB.Europe may be referring to the following Hioki product line (SM7110, SM7120, SM7420):Super MegaOhm Meters:https://hiokiusa.com/wp-content/uploads/2021/07/SM7110E9-17B.pdfEDIT: Echo88 seems correct. They posted just before I saw their links.Quite impressive, but I still do not understand ITTSB.Europe's argument that 'this conversation will not deliver anything useful'.At least now we are all aware of an unobtainable device that can measure better than anything else.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 12, 2021, 09:07:35 pm
content: Quote from: Echo88 on August 12, 2021, 08:52:05 pmAh, I remember this website! This might be a good read. Thank you for the link.

author: RaymondMack
author_rank: Regular Contributor
timestamp: August 13, 2021, 02:46:41 am
content: Correct me if I'm wrong, but HIOKI is not known for producing world class instruments. I've owned one of their "HI-Tester" battery impedance meters and I wasn't blown away by the build quality or knobology of the front panel. It was of acceptable quality though. That said, these newer instruments that leighcorrial has linked a pdf to do look nice, but not earth shattering. Current Keysight and Keithley electrometer/high resistance gear offer as good, if not better performance. Production equipment is not the same a metrology equipment. NIST makes custom standards and test setups while VISHAY is apparently buying their production line gear from HIOKI. I can't see how that makes HIOKI the go to source for resistance measurements. Sorry ITTSB.Europe I don't buy your blatant self-promotion of HIOKI. They are okay, but are not and have never been a premier instrumentation manufacturer.

author: Stray Electron
author_rank: Super Contributor
timestamp: August 13, 2021, 02:58:52 am
content: Quote from: Echo88 on August 12, 2021, 08:52:05 pmI'm curious about this statement that he made:"When Vishay Foil Resistor brand asked me of what quantity of samples I am going to need, I did the smart thought to order one more from all values.When samples arrived, I did measureall packs of ten resistors, and best one of its value this kept so to become part of this new project with code name: Ultra-High Precision resistor box!! "If he indeed tested at least ten of every resistor value then I would like to know what the range of measured values were and also what the resistor specification was.The article seems to be long on claims but short on facts and real numbers.

author: TiN
author_rank: Super Contributor
timestamp: August 13, 2021, 07:13:38 am
content: HIOKI RM3542A is pretty boring (metrology wise) 6.5 digit meter, clearly designed for speedy production line testing. It is no wonder that this meter was unable to measure any change in much more demanding VPG resistors, as it does not have the resolution or accuracy needed. Best Hioki's accuracy is 70 ppm a year for 10kOhm, so nothing to write home about and typical cheaper 6.5 digit benchtop DMMs like 34465A already have better specifications and performance. Obviously this is not any use for standard resistance metrology and calibration use when single-digit ppms are at stake.Sadly ITTSB's does not provide any useful insight about RM3542A instrument either, not a single test result , measurement data or even just teardown presented on his site ;(. Marketing claims caveat emptor.

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 13, 2021, 04:45:15 pm
content: Quote from: leigh corrigall on August 12, 2021, 09:07:35 pmDear Mr. Leigh Corrigall, my website this is made so to assist people up to your own caliber (level of education), as source of information.In the end of the day, you are after of new experiences, and you will get them sooner than many others, I bet that you are well aware of working systematically about conquering new subjects.While your DMM of choice, this belongs to an old industrial test system, this will not stop you exploring resistors at the tolerance as low as 1%.Thank you, you are welcome!

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 13, 2021, 04:59:37 pm
content: Quote from: TiN on August 13, 2021, 07:13:38 amITTSB respects the work of the best engineers of our planet, and it will never publicly display the gold-plated internals of an HIOKIbest in class tool.Amateurs and hobbyist as you are, they can find other web places to kill time or for their entertainment.And now its time for my own moment of entertainment, the castle of HIOKI it open it doors only to real KNIGHTS and you are not one of us, no matter of how you much you are trying to look as one of us.

author: 2N3055
author_rank: Super Contributor
timestamp: August 13, 2021, 05:04:22 pm
content: Self image inflation problems ??

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 13, 2021, 05:16:41 pm
content: Quote from: 2N3055 on August 13, 2021, 05:04:22 pmRead and ignored.When I do ignore stupidity, I gain more quality time for my self.

author: The Soulman
author_rank: Super Contributor
timestamp: August 13, 2021, 06:28:59 pm
content: Quote from: ITTSB.Europe on August 13, 2021, 04:59:37 pmWhat makes gold plating on the inside do any good apart from corrosion prevention?btw, with regards to actual performance, data speaks louder than words.

author: TimFox
author_rank: Super Contributor
timestamp: August 13, 2021, 07:06:02 pm
content: His expertise speaks for itself.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 13, 2021, 07:09:24 pm
content: "Complete analysis of RM3542A features this can be found by simply reading it User Manual (PDF), this presentation was indented to be a celebration in favor of Vishay Foil Resistor brand and of HIOKI E.E. Corporation."Our shiny Knight writes marketing wank for gear.

author: 2N3055
author_rank: Super Contributor
timestamp: August 13, 2021, 07:47:18 pm
content: Quote from: ITTSB.Europe on August 13, 2021, 05:16:41 pmJust to make sure i got it right, you just called me stupid?I know it seems redundant, I'm sorry, but I'm not very smart so just wanted to make sure i understood right.So I can crawl under my stone and live my life in shame and misery that I insulted a shiny, honorable knight with my presence and my audacity to speak up without permission..And cry softly in my misery, not to disturb greatness of Your Highness.....said he, and went off to whip himself for the sins he committed.

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 13, 2021, 09:43:32 pm
content: Quote from: Echo88 on August 13, 2021, 07:09:24 pmIs this the opinion of a Playmobil?It was my favorite toy, but I never started a serious conversation with one of them.Are you a Chinese living in Germany? My writing it is a pain to them no matter of their location.But one device manufactured by 100% Japanese components it is a source of admiration, always was.This is no SONY TV set, this made in China.

author: TimFox
author_rank: Super Contributor
timestamp: August 13, 2021, 09:49:09 pm
content: Could you re-phrase the last two lines of that post?

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 13, 2021, 09:53:08 pm
content: Quote from: TimFox on August 13, 2021, 07:06:02 pmYou are a true source of amusement, the expertise this is measured by you giving exams every single day.And the amount of your worth or value, this is a decision of the better ones than you.If they decide that you do measure up, then your name gets recorded in their wall too.http://www.vishaypg.com/foil-resistors/case-studies/

author: TimFox
author_rank: Super Contributor
timestamp: August 13, 2021, 09:56:54 pm
content: My name is already written in the Book of Life, thank you.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 13, 2021, 11:36:57 pm
content: Geez, cant even argue anymore with you. Just seems wrong after visiting your forum.

author: dietert1
author_rank: Super Contributor
timestamp: August 14, 2021, 05:36:30 am
content: As far as i understand, personal attacks like the one started by TiN are undesirable in this forum. If you have nothing to contribute but aggression and personal disappointments, please stop it. As far as i remember, the most recent contribution of TiN in this forum about the LM399 cool-down did not at all require a metrology DMM.There are technicians who want to be engineers and engineers who want to be scientists. No problem.Regards, Dieter

author: Simon
author_rank: Unknown
timestamp: August 14, 2021, 07:17:11 am
content: Can we quit the arguing please. I'll read through in a bit and work out if anyone needs banning.OK, I see, it's our old friend Kiriakos returned. Well your choice mate, start the same crap as before and you get banned like before

author: ITTSB.Europe
author_rank: Contributor
timestamp: August 14, 2021, 09:11:06 am
content: Quote from: Simon on August 14, 2021, 07:17:11 amI do not give a shit about banning as and before.Now get busy of taking heads of several accounts which polluting other people topics.By this way you will prove your friendship to the ones who care for it.

author: Simon
author_rank: Unknown
timestamp: August 14, 2021, 11:21:47 am
content: Sorted!

author: TiN
author_rank: Super Contributor
timestamp: August 28, 2021, 06:38:25 pm
content: Got updated annual drift chart based on data of 21 (yep, twenty one) pcs ESI SR104 from different manufacturing dates. As memory refresher, these standards are specified at 0.5ppm/year drift by design (after first two years), but in reality and worldwide metrology labs experience they show much better performance numbers. This plot shows that too, based on calibrated units, owned by metrology enthusiasts. Most SR104 are stable to <0.1ppm/year.Credits to zlymex for this work, I've just added few SR104s data and updates from 2019-2021 calibrations.I'm very happy to own the golden one with <10 ppb/year drift.(According to NMI-level calibrations I've got on it with uncertainty 0.10 ... 0.16 ppm).If you have SR104 data/history , please do share so we can get this plot even bigger. Not easy nor cheap to monitor SR104's over multiple years.

author: mzzj
author_rank: Super Contributor
timestamp: September 01, 2021, 03:27:09 pm
content: Quote from: TiN on August 28, 2021, 06:38:25 pmNot SR104 but it looks like our 100ohm Tinsley 5685A has drifted less than 0.2ppm in 12 years. (half a guess as local NMI provides 0.4ppm uncertainty)Many 5685A's are known to be stable to 0.2ppm over 20 years. (We got lucky with the tempco also, IIRC 0.05ppm/cel.)

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 01, 2021, 05:58:24 pm
content: Quote from: TiN on August 28, 2021, 06:38:25 pmAmazing, Illya. This is what this thread is about!EDIT: Are you sure you can assume that the ppm/a is a linear response? Most references illustrated do not have enough data to justify that assumption. The response might be more like a saturation curve. Unfortunately, it might take several decades of yearly measurements from the time of manufacturing to find out.These resistors are most impressive. One day, I hope to own one too.Does this chart have anything to do with your latest articlehttps://xdevs.com/article/g6675a/?Regards.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 01, 2021, 09:39:56 pm
content: The drift does not have to be linear, but it also does not have to be a simple relaxation. The treatment in the time in between can have an effect, like vibrations and changes in temperature (e.g. hysteresis) and maybe the magnetic field. At the low level it is also some drift and adjustments at the national institutes. Part of the drift / noise may also be on that side.

author: TiN
author_rank: Super Contributor
timestamp: September 01, 2021, 10:58:24 pm
content: Quote from: leighcorrigall on September 01, 2021, 05:58:24 pmI'd rather say the opposite if we trust statistics. There are 21 resistors of different year of manufacture and different owners/labs but they all somewhat came to same around 0.1ppm/year figure.Sure, there must be some non-linearity and outliers, but given the limited uncertainty (even best of the best labs can only give 0.1-0.2 ppm uncertainty of one fixed day measurement!) this does give idea that probability of good resistor jumping few ppm outside of expected value exists, but low (since it would need to jump back to same magnitude to reach last measured value).Anyway, I'll continue with effort on my unit and hopefully will be able to answer your question by year 2032 or so.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 01, 2021, 11:25:22 pm
content: Quote from: Kleinstein on September 01, 2021, 09:39:56 pmI think Kleinstein is correct here.Ultimately, these curves are so subtle that they would be very difficult to argue. I take back my previous criticism.Half-jokingly, I have no doubt that TiN will have an answer for me on my 43rd birthday.

author: TiN
author_rank: Super Contributor
timestamp: September 02, 2021, 12:21:52 am
content: Also side note, chart calibration points do take SI Ohm adjustment in 1990 into account.

author: bdunham7
author_rank: Super Contributor
timestamp: September 02, 2021, 12:34:31 am
content: Quote from: TiN on August 28, 2021, 06:38:25 pmAm I correct when I see that some of those only have two measurement points--for example the solid red one that shows 1969 and 2021?And they all sort of go up at similar slopes over the years?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 02, 2021, 12:45:03 am
content: Quote from: bdunham7 on September 02, 2021, 12:34:31 amThis is why I made my point about the curvature. Any two points make a line. This is likely the best available data on a collection of standards.Quote from: bdunham7 on September 02, 2021, 12:34:31 amAs pointed out earlier, the slopes are extremely gradual (which is great as a standard), it would be difficult to discriminate the data -- at least in my limited capacity.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 03, 2021, 03:09:24 am
content: Since custom Vishay voltage dividers are becoming difficult to purchase these days in reasonable timeframes, I have recently purchased two off-the-shelf Vishay SMNZ resistor networks based on Z-foil technology for a precision voltage application that I am working on as a substitute for a Vishay Accutrim trimming potentiometer and a VHD200 voltage divider. Originally, I was going to borrow the voltage buffer concept from kj7ehttps://www.eevblog.com/forum/metrology/ltz1000-10v-buffer/msg1435737/#msg1435737that relies on a trimmer to achieve 10 DCV.SMNZ:http://www.vishaypg.com/docs/63117/smnz.pdfAccutrim:http://www.vishaypg.com/docs/63056/12801285.pdfhttp://www.vishaypg.com/docs/63054/Accutrim_1260_RJ24.pdfVHD200:http://www.vishaypg.com/docs/63036/vhd200_144.pdfMy interest in this resistor network technology began when TiN pointed out a significant disadvantage when using trimmers for precision voltage standards in a private email, which made me contemplate the use of a 4 resistor SOIC package instead. The disadvantage being that a trimmer can lose its position during transportation (rendering it pointless as a transfer standard), the trimmer TCR through the wiper is 25 ppm/°C (although promoted as '5 ppm/°C', which refers to the resistor itself), and thick film trimmers are not as stable as Vishay's Z-foil technology over time. I can ramble on about the trimmers, but you can read the datasheets for yourself. The advantage of the resistor network is that it is compact in size and will share a similar TCR. Furthermore, networks can provide a selectable fixed-resistance when the soldering connections or even with quality jumpers.These are the various configurations that come to mind when applying a Vishay Y1747V0227AT9W (4 x 350 Ω SOIC-8 package):configuration resistance valueR|R|R|R 87.5R|R|R 116.67(R+R)|R|R 140R|R 175(R+(R|R))|R 210(R+R)|R 233.33(R+R+R)|R 262.5R 350R|R|R+R 466.67R|R+R 525(R+R)|R+R 583.33R+R 700R|R+R+R 875R+R+R 1050R+R+R+R 1400The average resistance step size of the 4 x 350 Ω resistor network is about 50 Ω until 583.3 Ω, which is fairly reasonable for my application. If the maximum resistance limit of interest is 262.5 Ω, then the average resistance step size reduces to 30 Ω. Even though the resistor network cannot compete with the continuous resistance values that a trimmer provides for a voltage divider, this package balances versatility and stability in a precision application.For context, my resistor application is a critical component to a 10 DCV output stage for an LTZ1000ACH output board. The design was modified from TiN's FX-ref board:https://xdevs.com/article/792x/You can view my resistance network simulation with Falstad (open the attached txt file withhttps://www.falstad.com/circuit/) to get a sense of my application. The voltage divider network was designed to handle any LTZ1000 output and convert it into ~10 DCV.1) The variable LTZ1000 input voltage range is based on the standard deviation of all available reported measurements (n = 16) I could find for the KX-ref, in addition to a multiplication factor of 4. This resulted in the range of approximately 7.047 to 7.216 DCV. Fun fact: my recent KX-ref is within this range (7.09295 DCV) but rather low in comparison to the mean. It is outside the limit of 1 standard deviation (7.11052 to 7.15267 DCV). The LTZ1000 datasheet provides a wide output range of 6.9 to 7.5 DCV.2) Read the picture for a description of how to obtain ~10 DCV with the precision resistance network and a very small trimmer (if necessary). The simulation should be fairly intuitive. For example, with an input of 7.09259 DCV, the circuit can achieve an output of 9.951 DCV (0.5 % tolerance) without a trimmer. If a trimmer is necessary, then setting the trimmer to 70.2 Ω, it should be possible to achieve ~ 10 DCV. In this scenario, the optional trimmer would not contribute much to the overall TCR since the divider would be 10 kΩ / (703.33 Ω +70.2 Ω).Anyways. That is it for me. Hope I haven't confused anyone with my ramblings.Enjoy!

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 08, 2021, 06:07:08 pm
content: Today, a package of glass-coated wire wound resistors arrived from Russia! A special thank you, shodan@micron.You can learn more about them and their history at:https://www.eevblog.com/forum/metrology/mpx(mrh)-resistors/A video from the thread:https://www.rvmagnetics.com/productionQuick 4-wire 6.5-digit DMM measurement without shielding reveals the following:20 MΩ: (- 0.0295 %, - 0.1235 %, - 0.0820 %, - 0.0975 %)10 MΩ: (- 0.0040 %, + 0.0026 %, - 0.0122 %)10 kΩ: (+ 0.326 %)Very impressive values considering the age and that these resistors were sitting in a warehouse box for decades.

author: bsw_m
author_rank: Frequent Contributor
timestamp: September 08, 2021, 06:42:45 pm
content: Strange result for a 10k ohm resistor. They (S5-60) never drifted so much.Please check your measurements.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 08, 2021, 07:04:43 pm
content: Quote from: bsw_m on September 08, 2021, 06:42:45 pmThank you for pointing that out.It is very likely that the Keithley 2000 DMM is not within tolerances. It is on loan until I get a replacement.My Advantest R8340 says that it is 10.000 kΩ in two-wire mode. Until I get my Advantest R6581T calibrated/fixed, I won't be able to do much. I'll remeasure them again soon.

author: Anders Petersson
author_rank: Regular Contributor
timestamp: September 09, 2021, 11:54:57 am
content: Quote from: leighcorrigall on September 08, 2021, 06:07:08 pmShodan has sadly removed all his content from Eevblog. For some topics, information is still available in Russian at his sitehttps://ampnuts.com/Quote from: leighcorrigall on September 08, 2021, 07:04:43 pmPerhaps you have another 10 kOhm resistor with known value that you can check yout DMM against.

author: dietert1
author_rank: Super Contributor
timestamp: September 10, 2021, 08:28:17 pm
content: Look at this one and find the error!On offer at ebay (US).Regards, Dieter

author: 2N3055
author_rank: Super Contributor
timestamp: September 10, 2021, 08:35:33 pm
content: Quote from: dietert1 on September 10, 2021, 08:28:17 pmOK I give up, what's the error?Do you mean spec of 11111,10 while having last switch switching 0,01 ?

author: iMo
author_rank: Super Contributor
timestamp: September 10, 2021, 08:36:01 pm
content: Decimal point in wrong position?

author: 2N3055
author_rank: Super Contributor
timestamp: September 10, 2021, 08:39:58 pm
content: Quote from: imo on September 10, 2021, 08:36:01 pmSwitches go to 10...

author: dietert1
author_rank: Super Contributor
timestamp: September 10, 2021, 08:42:25 pm
content: I found another image with a Fluke hand meter indicating 11.11 KOhm. Each knob has positions 0 .. 10! So it's a creative interpretation of decimal numbers with a decimal point position that depends..Regards, Dieter

author: 2N3055
author_rank: Super Contributor
timestamp: September 10, 2021, 08:52:27 pm
content: Quote from: dietert1 on September 10, 2021, 08:42:25 pmExactly, switches go to 10 and that means you have to carry 1 to next upper digit. So there are alternative combinations that give same nominal resistance.Funny thing, 11111,10 spec is in original datasheet too. Maybe last digit is lost when set to max resistance..I don't remember, it's been years since I used one, only remember laughing that resistance box needed a manual to operate. Guys in lab called it Enigma... :-)But the specs are great...

author: The Soulman
author_rank: Super Contributor
timestamp: September 10, 2021, 08:55:45 pm
content: Just add up the numbers.

author: bdunham7
author_rank: Super Contributor
timestamp: September 10, 2021, 09:01:37 pm
content: Quote from: 2N3055 on September 10, 2021, 08:52:27 pmIt's not lost, just moved to the left like everything else.Why is the minimum specified as 100R?

author: The Soulman
author_rank: Super Contributor
timestamp: September 10, 2021, 09:14:36 pm
content: Quote from: bdunham7 on September 10, 2021, 09:01:37 pmSpecified accuracy is from 100 to1000011111.10 Ohms, below it will work fine only less accurate (switch contact resistance is attributing moreon lower ranges).Above 10.000 Ohms it will still be pretty accurate, but it just isn't specified.Edit: had to look at the picture again.

author: dietert1
author_rank: Super Contributor
timestamp: September 11, 2021, 05:25:29 am
content: I think one can do the "10" or even higher on the most significant digit, but the other digits should remain 0 .. 9. So the maximum resistance would be 10 999.99 Ohms. Anyway one can use it that way to avoid confusion.Maybe the idea was to provide a built in means of checking the lower decades at calibration time.Regards, Dieter

author: 2N3055
author_rank: Super Contributor
timestamp: September 11, 2021, 08:17:20 am
content: Quote from: dietert1 on September 11, 2021, 05:25:29 amThat was the idea I think.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 24, 2021, 08:07:04 pm
content: Quote from: Anders Petersson on September 09, 2021, 11:54:57 amSorry about the delay. Here are the results.Keithley 2000 (uncalibrated)Vishay Y4078: 1.00065 kΩ @ 23.4 °C on 2021-09-24C5-60T: 10.00711 kΩ @ 23.5 °C on 2021-09-24Vishay Y4078: 10.00680 kΩ @ 23.4 °C on 2021-09-24Keithley 6500 (NISTcalibratedtraceable within 1 month of measurements)Vishay Y4078: 1.00000 kΩ @ 28 °C on 2021-04-13Vishay Y4078: 9.99997 kΩ @ 28 °C on 2021-04-13With compensation,C5-60T: 10.00027 kΩ @ 23.4 °CI must have made a calculation error last time I measured it.The Keithley 2000 seems to be OK. Measurement error could explain why the resistor is out. Until I perform a direct measurement with a calibrated instrument, I won't know.

author: TiN
author_rank: Super Contributor
timestamp: September 24, 2021, 11:21:49 pm
content: Your 6500 is not NIST calibrated, it it calibrated traceable to NIST. Small wording change but huge practical (and money) difference

author: guenthert
author_rank: Frequent Contributor
timestamp: October 01, 2021, 10:38:25 pm
content: Quote from: shodan@micron on October 01, 2021, 10:21:46 pmHuh, a IPv6 address in the wild. More so, an unroutable IPv4 address embedded in an IPv6 address.How did that happen? Might that just be a configuration issue on their firewall? What happens when you use an IPv4 address?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: October 07, 2021, 01:45:45 am
content: Quote from: leighcorrigall on September 24, 2021, 08:07:04 pmResults of a freshly calibrated NISTtraceableAdvantest R6581T (ACAL = ON, NPLC = 100, MEAN = 100):10,000.065 ± 0.003 kΩ (n = 7) on the 100 kΩ range @ 25.89 °C, 64.94 % RH10,000.1614 ± 0.0003 kΩ (n = 10) on the 10 kΩ range @ 25.92 °C, 64.51 % RHTherefore, the resistor is within a 0.002 % tolerance.Thank you for the resistor, shodan@micron.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: October 11, 2021, 02:20:58 pm
content: Does anyone have suggestions for a multi- or single-stranded wire that can be used to connect a resistance standard to a binding post? Many distributors carry hookup wire that is tinned or alloyed. I would prefer copper or silver wire.I would like to mimic what Fluke or EIT has done with their standards:https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg891672/#msg891672https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg891673/#msg891673

author: bdunham7
author_rank: Super Contributor
timestamp: October 11, 2021, 02:28:18 pm
content: I stripped down an old 4-wire POTS (phone) cable that I removed from the attic and got 4 nice pure copper color coded 24AWG wires that I twist up and use for voltage references and the like--just bare wires, no terminals.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: October 11, 2021, 03:07:45 pm
content: Quote from: manganin on March 05, 2016, 10:14:56 amhttps://www.eevblog.com/forum/metrology/replacing-teflon-cable-with-cat6-in-metrology/msg887437/?topicseen#msg887437

author: DavidKo
author_rank: Frequent Contributor
timestamp: October 25, 2021, 07:54:01 am
content: Look for the oxygen free speaker cable. It is cheap, but check the isolation. I have made a cable with bananas and there is resistance between wires, you can always split it to two single wires and use air as insulator.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: October 28, 2021, 02:48:05 pm
content: I use CAT6 cable where I need a screen and where the wire resistance is not a major issue (voltage measurements) however it is not very flexible and needs careful handling. For mid-low resistance measurements and high currents I build my own test leads from silicone rubber isolated wires andStaubli plugsas on the photo. I've done some isolation tests and silicone rubber is pretty good, leakage current measured in a fixture as on the photo below is <0.5pA at 100V (a plain mains grade PVC isolated wire measured in the same way leaks about 100pA at 100V). The Staubli plugs are made from gold plated "copper alloy" (somewhere I've read "beryllium copper") unlike a bronze used for the majority of banana plugs and test leads like on the photo easily give me offsets below 1uV without special measures when used to connect something like SR1010 and KVD. I used two different makes of silicone rubber isolated wires, oneChinese make from Amazon(1.5mm2 , 400 strands of tinned copper, 600V 20A rated) which is surprisingly good and comes in various colours. 0.9m of this wire is about 10mOhm terminated. Another is adouble-insulated wire from RS(1mm2, 250 strands of plain copper, 1000V 20A rated) which comes pre-cut at 1.2m and at that length measures about 25mOhm terminated. Both wires are very flexible and nice to use.CheersAlex

author: TimFox
author_rank: Super Contributor
timestamp: December 17, 2021, 02:40:42 pm
content: Are the units with extremely high resistance values, such as 1000 megohm, three-terminal TEE/WYE networks?If not, what is the resistance material?

author: bsw_m
author_rank: Frequent Contributor
timestamp: December 25, 2021, 12:30:07 pm
content: Some glass encapsulated microwire resistors.С5-66 333.3MOhm ±0.02% TCR ?МРХ 100MOhm -0.1% TCR: ?РМП-7 10MOhm ±0.02% TCR 10 ppmС5-60 1MOhm ±0.01% TCR 5ppm

author: bsw_m
author_rank: Frequent Contributor
timestamp: December 25, 2021, 12:59:28 pm
content: Also good sapphire insulators for DIY high-resistance standards.The large insulator has a diameter of 10mm, a thickness of 4mm and a hole diameter of 2mm.

author: bobAk
author_rank: Contributor
timestamp: December 25, 2021, 11:35:30 pm
content: The paper version is not custom. You forgot something that must be still on this version for the resistor to be preferred.

author: bobAk
author_rank: Contributor
timestamp: December 26, 2021, 12:38:33 am
content: That's a coincidence. My experience suggests otherwise. And “best of the best” sounds odd to mrh, albeit with a paper label. However, let me remind you once again - a paper label is not a custom, you forgot to indicate something additionally. How many units have been measured?

author: bobAk
author_rank: Contributor
timestamp: December 26, 2021, 12:51:42 am
content: Can I see the results, for "paper label"? With the separation of mvsg(мвсг) or mrh, for presentability.

author: bsw_m
author_rank: Frequent Contributor
timestamp: December 26, 2021, 01:04:43 am
content: I'm measure about 120pcs 30+ years old 100MOhm 0.1% MRH resistors without paper label.All resistors have -0.02%.....-0.06% error from nominal value. Except one which was faulty.

author: bobAk
author_rank: Contributor
timestamp: December 27, 2021, 10:00:27 am
content: You can send me the result in pm if you are afraid of people in black. Offtopic. How does mrh hurt me? Especially if you haven't even figured it out mrh or mvsg. Let's talk seriously without the "pertuberant period word game".

author: 1audio
author_rank: Frequent Contributor
timestamp: January 25, 2022, 07:50:54 am
content: I have a question relating to trimming precision resistors. I have 10 JRL 250K .01% resistors. They are all within tolerance (at least as far as I can tell with my limited resources). I want to build a variation on a SR1010MT divider with them. ESI used this circuit to make the resistors adjustable. What pitfalls and aspects should I be aware of both for the resistors and the trimmers (scaling to the 250K level I'm working with). My goal is to trim all the resistors to be as close as I can to each other.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 25, 2022, 09:47:47 pm
content: In my experience those schemes work well and have few pitfalls. You can easily work out the sensitivity for each part to be sure what you use is good enough. The pot is often the limiting factor and the smaller range it covers, the better. I also have some JRL resistors but don't know how good they really are.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: January 25, 2022, 10:39:21 pm
content: If you are serious about trimming, you could try the following Vishay products:http://www.vishaypg.com/foil-resistors/trimmers/You should consider the 'through the wiper TCR' and stability factor in your design.Through the wiper TCR examples:Accutrim 1240/1260: 10 ppm/°CAccutrim 1285G: 5 ppm/°CIf TCR must be minimized, then the trimmer needs to be small because 5 ppm/°C can contribute a lot depending on the configuration. There are trade-offs when designing any circuit.Keep in mind that vibrations can potentially knock trimmer wipers. If a trimmer is necessary, you might want to get one with the maximum number of turns per ohm to minimize the potential risk of offset due to vibrations.You could also go with a more permanent solution by implementing a resistor network/array instead of a trimmer and 'trim' by various combinations of series and parallel resistances. I have a 4 x 350 Ω example in a past post:https://www.eevblog.com/forum/metrology/precision-resistors-general-thread/msg3664213/#msg3664213Good luck

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 26, 2022, 12:31:04 am
content: Another way to trim, used by Julie in some of their products, is to get a length of manganin wire and put a short piece in series with all the resistors to get them up to the value of the high one. You can't adjust it with a screwdriver but once it's done it isn't going to move much.

author: 1audio
author_rank: Frequent Contributor
timestamp: January 26, 2022, 06:59:40 am
content: I actually have a small supply of the Vishay foil trimmers. Not sure how many and what value. The Manganin wire idea is quite interesting and would probably work OK. I will need to find a source of around the right resistance. On my Keithley the 250K resistors are all within about 40 Ohms which is inside the .01% original tolerance. Given that these predate zip codes (1963) its safe to say they are well aged!.

author: TiN
author_rank: Super Contributor
timestamp: January 28, 2022, 06:01:06 am
content: Little report on testing of 1000 Ω Guildline 9330 resistor. This resistor was acquired from second-hand market. There was no known history other than calibration sticker label on resistor body from Cal-Matrix Metrology, Inc. which does not seem to have a web-site but located in Burlington, ON, Canada. Last known value from sticker is1000.0250 Ωmeasured at somewhat strange +24.0 °C with unknown uncertainty.Resistor arrived in decent shape without any damages, just slightly dirty. There was no oil residues that could suggest use in bath.Other than already mentioned value and calibration date May 13, 2015 there is no much other useful information from the stickers.So we will start measurements on this resistance standard and collect history starting from clean slate. Before that can happen binding posts and brass nuts were carefully cleaned with soft abrasive cloth and cleaned with 99% IPA.Resistor then was connected to measurement setup with Measurements International 6010B DCC bridge to perform performance tests.RAW Datalogs and results for 1000 Ω Guildline 9330, S/N 45793For the initial measurements at xDevs Lab in January 2022 this unknown resistor was placed in an air bath at nominal 23.0 °C ±0.1 °C. For better accuracy DUT temperature was measured with separate Omega capsule RTD and Fluke 1529 thermometer readout. This RTD was installed inside Guildline 9330 thermal well. The average temperature of the resistor was measured to be 22.992 °C and uncertainty of this measurement estimated ±0.18 °C. Standard resistor used in first test wasthermally stabilized Fluke 935-10kΩ S/N 001, placed in lab ambient environment.Fluke 935was running on battery during the measurement period.Ratio between Fluke SL935-10k (316 µA) and MM Guildline 9330-1k (3.16 mA)Ratio between Fluke SL935-10k (316 µA) and MM Guildline 9330-1k (3.16 mA) in reverseRatio between xDevs.com's ESI SR104 (316 µA) and MM Guildline 9330-1k (3.16 mA)Ratio between T2 ESI SR104 (316 µA) and MM Guildline 9330-1k (3.16 mA)Ratio between Fluke 5720A/H1 9999.9769 Ω (316 µA) and MM Guildline 9330-1k (3.16 mA)Uncertainty and transfer analysis with Sandia PSL's open-source toolkitRun, dateRxIxRsIsReversal timeResultSDEV, ppmppm from averageDeviation from stickerFSL935 FWD, JAN.9.20229999.9757 Ω ±0.3 ppm0.316 mAG9330-1k3.16 mA20 s1000.03476 Ω±0.04+0.06 ppm+9.76 ppmSR104 forward, JAN.10.202210000.00128 Ω ±0.13 ppm0.316 mAG9330-1k3.16 mA20 s1000.03477 Ω±0.03+0.07 ppm+9.77 ppmSR104 T2, JAN.12.202210000.0013 Ω ±0.13 ppm0.316 mAG9330-1k3.16 mA20 s1000.03463 Ω±0.04-0.07 ppm+9.63 ppmAveragedN/A0.316 mA1000.03470 Ω ±0.18 ppm+9.72 ppmFinal 27.JAN.2022N/A0.316 mA1000.03477Ω ±0.22 ppm+9.77 ppmBased on these measurements we can estimate long-term drift of this resistance standard. To do so, one can take previous known calibration value from date May 13, 2015 which was 1000.0250 Ω withunknownuncertainty. That was 2452 days from today, 27.JAN.2022. Today measured value is1000.03477 Ωwith uncertainty ±0.22 ppm (95%).Deviation between two values =( (1000.03477 Ω / 1000.0250 Ω) - 1 ) * 1e6 = 9.77 ppm of change.Making assumption of linear steady drift (which may not be true, but we don't have anything else to work with just two points history) we can calculate daily drift =9.77 ppm / 2452 daysequals0.003985 ppm/day.By multiplying this into 1 year =0.003985 * 365 days = 1.454 ppm/year. This is still well within Guildline 9330 specification of ±3.5 ppm/year.Temperature coefficient was also measured using two active Peltier air bath chambers.RAW Datalog page with tempco measurement experimentMore details and internal design of Guildline 9330's also availableon my review/teardown article.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 28, 2022, 08:07:58 am
content: What is the purpose of the two contacts are far behind the housing? Why are they so far?

author: TiN
author_rank: Super Contributor
timestamp: January 29, 2022, 12:45:42 am
content: C1 and C2 are current terminals for Kelvin connection?.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: January 29, 2022, 12:57:22 am
content: Quote from: MegaVolt on January 28, 2022, 08:07:58 amAlthough distance matters, I think that the standoffs are made of solid copper. The unusual feature may have been strategically placed as part of a grand design.

author: TiN
author_rank: Super Contributor
timestamp: January 29, 2022, 01:30:41 am
content: They are solid copper bars, yes. Typically standards of such designs with horns designed to support low-contact resistance mercury-wetted stands for various metrology applications.This is not common today, but many of standards designed back then are working great today too, so no reason for change. Also it is convenient to use when you have some room for fingers to get those copper forks extra tight, so no ppb have chance to escape

author: guenthert
author_rank: Frequent Contributor
timestamp: January 29, 2022, 02:33:12 am
content: Quote from: leighcorrigall on January 29, 2022, 12:57:22 amIn which way?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: January 29, 2022, 02:41:18 am
content: Quote from: guenthert on January 29, 2022, 02:33:12 amFor instance, the temperature difference at the 4 junctions. Copper is a great thermal conductor so the effects are lower.EDIT:https://www.eevblog.com/forum/projects/4-wire-resistance-and-the-seebeck-effect/

author: Kleinstein
author_rank: Super Contributor
timestamp: January 29, 2022, 06:53:37 am
content: The thermal EMF is known problem with precision resistors. It was a major point going from konstantan to manganin.For the modern low TC materials the thermal EMF relative to copper is an important point.It not only effects the large standard resistors, but also more normal ones in low voltage circuits. As an example I see quite some thermal EMF with temperature gradients at PTF56 resistors.The standard resistors are usually used at a relatively low power and in a isothermal environment. I would consider the shape with the protruding connections also a practical solution for holding the resistors in a oil bath.The thermal EMF effect seen in the video is likely to a large part from the clips at the test cables. The problem is a temperature gradient in non copper parts only.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 29, 2022, 10:05:34 am
content: Quote from: Kleinstein on January 29, 2022, 06:53:37 amThis is a good version. Need to check whether all resistors with long contacts are designed to work in the bathroom with butter.

author: alm
author_rank: Super Contributor
timestamp: January 29, 2022, 01:34:42 pm
content: Quote from: TiN on January 29, 2022, 01:30:41 amExcept that in this case the bottom of the "horns" are insulated, and I don't think this insulation is designed to be removable.Another reason I can imagine is easy series configuration as voltage divider or to compare two resistors with an equal current flowing through them, like how the Fluke 5450A is adjusted to an external standard resistor.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 29, 2022, 03:26:51 pm
content: Wow, that HP divider just boggles the mind!

author: miro123
author_rank: Frequent Contributor
timestamp: January 29, 2022, 03:50:50 pm
content: Quote from: TiN on January 28, 2022, 06:01:06 amThanks for sharing. As novice to this topic I have few stupid questions. I have checked your site but I did not find the answers -https://xdevs.com/article/tcr_test/- How does it look like your setup?- What is the meaning of following parameters? - Rx, Ix, Rs, Is and "Reversal time"Thanks in advance

author: TiN
author_rank: Super Contributor
timestamp: January 29, 2022, 05:55:02 pm
content: Nothing stupid in questions, we all started somewhereBlock diagram of setup used is essentially same as this. Bridge is sourcing Ix current into connected resistor and then matching current Is multiplied by ratio sourced into second resistor. This is done using internal transformers and nanovolt detectors, and by keeping ratio very stable this setup essentially allow to calculate unknown resistance value from known calibrated resistance standard to <0.03ppm resolution. Also since currents are compared using switchable transformer windings, there is no resistance or voltage reference drift or temperature coefficients unlike in any DMM with resistance function.This is typical setup for many top-level calibration labs and NMIs, outperformed only by CCC and QHR systems. Currents can be programmed to any value from <1mA to up to 250mA (or thousands amperes with high-power extenders for purposes of high-power shunt calibrations).On block diagram you see Rx and Rref, on my earlier post Rs is considered Rref, same thing, different wording.To cancel parasitic thermal EMFs (we talking single nanovolts importance to obtain such high resolution) bridge has reversal time that sets period of current polarity reversals. Smaller resistors work with 6-10 seconds reversal, while larger like 1k-10kOhm require bit longer times.Hopefully this helps.

author: TimFox
author_rank: Super Contributor
timestamp: January 29, 2022, 10:35:18 pm
content: In that beautifully-drawn diagram, does "Ground" on the DCC Bridge connect to anything, or is it internally connected to the PE of the power cord?I'm well aware of the difference between Ground and Guard, but am often frustrated that TME often does not have a front-panel ground/chassis/panel connection to facilitate shielding (braid over test wire bundles) the wires between units.

author: TiN
author_rank: Super Contributor
timestamp: January 29, 2022, 10:44:50 pm
content: In my setup ground is connected to PE and internally to digital/analog grounds. Typical resistance standards do not have mains power, so they are true floating devices and there is no need for additional grounding to standards here. Different story for high resistance stuff, but DCC bridges typically operate only up to 10-100kOhm max. High resistance story is for another thread.

author: alm
author_rank: Super Contributor
timestamp: January 29, 2022, 10:47:33 pm
content: Quote from: Conrad Hoffman on January 29, 2022, 03:26:51 pmIndeed! It's from the1966-04 issue of HP Journal. They were trying to sell the HP 11102A/11103A/11104A/11105A standard resistor that had as distinguishing feature that it had a small adjustment range so you could closely match them. A voltage divider is a possible application, though this looks very expensive. The resistors were only in the catalog for one year. I'm guessing they either didn't sell well or didn't perform as well as they hoped.

author: 1audio
author_rank: Frequent Contributor
timestamp: February 07, 2022, 01:54:59 am
content: I bought into the idea of using resistance wire to trim the resistors. And bought a roll of Evanohm from eBay. Now that I have it I'm looking at #38 awg bare wire. . . that is 800 Ohms per foot. Now to figure out how to work with this stuff. Any suggestions?

author: alm
author_rank: Super Contributor
timestamp: February 07, 2022, 02:29:39 am
content: Termination will probably be your main challenge. From what I've read, the only reliable way is to weld it to a compatible material (not copper). This has been discussed on this forum a couple of times. Especially pay attention to the posts by Edwin G. Pettis, who has many years experience working with Evanohm. This thread contains some useful info:https://www.eevblog.com/forum/metrology/manufacturing-custom-high-precision-low-tc-resistors/

author: 1audio
author_rank: Frequent Contributor
timestamp: February 07, 2022, 03:50:07 am
content: It seems I'll be looking for something else for this project. The Evenohm has too much overhead to be useable. Is anyone interested in a full still packaged roll of EvenOhm thats marked =/- 5 ppm TCR?Edit- I just checked and I have 12 100 Ohm 15ppm TCR Vishay foil trimmers. I should have checked before buying the wire. The trimmers will be the easy solution. I'll make up a little PCB for all the connections.

author: ramon
author_rank: Regular Contributor
timestamp: February 07, 2022, 03:40:35 pm
content: Quote from: 1audio on February 07, 2022, 03:50:07 amwire diameter?

author: 1audio
author_rank: Frequent Contributor
timestamp: February 09, 2022, 02:31:44 am
content: It says .0095 I think that's 9.5 thousandths of an inch. Its very fine wire. Pay for the shipping and its yours. PM me.

author: miro123
author_rank: Frequent Contributor
timestamp: February 09, 2022, 09:35:41 am
content: I have few general questions.1. What are the pre-condition before starting resistor performance test. For example – X % humidity, T=Y C for at least Z days/months/years2. Is baking of Vishay precision resistors a good practice? If yes what is the temperature profile?3. Should I ask for it the Vishay application engineers or somebody already asked?I’m asking those questions because I’ve ordered 50pcs of Vishay RC02 resistors

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: February 09, 2022, 01:01:53 pm
content: Quote from: miro123 on February 09, 2022, 09:35:41 amHi Mirco123.What is your intended use for these resistors? Vishay resistors are excellent, well characterized, and their specifications are met or exceeded. Why not purchase resistors that are already made for your intended design? I suggest Z foil for long-term stability.Do you mean Vishay's Post Manufacturing Operations (PMO)? If so, what do you expect the PMO to do? If you cannot answer the question, you may want to reconsider asking Vishay to perform additional operations.

author: ramon
author_rank: Regular Contributor
timestamp: February 09, 2022, 02:54:54 pm
content: Quote from: 1audio on February 09, 2022, 02:31:44 amThank you, but that wire is waaaay too thin. I learned that on my first spool.I will pass for the 2nd time, as in fact I already saw that spool on summer last year and was tempted to buy it. But was somewhat able to control myTEA* WSA syndrome. So I only bought him the spools with the diameters (or materials) that I didn't have before. Like a PDAG spool, Nickel (Alloy 200), Constatan (Advance), and a Nickel spool with TCR 5000 for making 5000 PPM/K RTD (not on that picture, that one is in another box).That seller got the spools from a closed Clarostat manufacturer facility, and there are many nice and special alloys, he even got some tooling for resistor making. The only wire material that he lacks is Manganin but I already got that covered from Europe source (thanks to a noble man who was a precision resistor maker - many years ago - in Italy).*Wire Spool Anonymous

author: miro123
author_rank: Frequent Contributor
timestamp: March 22, 2022, 05:23:16 pm
content: Do you have history of resistors, e.g. measured value, Alpha, Beta from the past?

author: bsw_m
author_rank: Frequent Contributor
timestamp: May 20, 2022, 07:47:39 pm
content: Teardown of a МРХ wirewound precision resistors.From up to down, resistive elements from:1. МРХ 100 MegaOhm 0.05% tolerance.2. МРХ 100 MegaOhm 0.1% tolerance.3. МРХ 300 MegaOhm 0.05% tolerance.The second picture shows the resistors themselves in the same order. For comparison, there is a 100M 1% resistor manufactured by TE:https://www.te.com/usa-en/product-3-1625959-3.htmlP.S. these resistors are very stable.After 30 years from the date of manufacture, all fit into the tolerance with a margin, many with a 2-fold margin.

author: sahko123
author_rank: Frequent Contributor
timestamp: May 20, 2022, 09:38:54 pm
content: Is there any particular reason certain oils are used? Is because of corrosion issues? Or even humidity issues?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: May 20, 2022, 10:03:13 pm
content: Quote from: sahko123 on May 20, 2022, 09:38:54 pmSome oils spoil or are corrosive because of contamination. Other factors are heat transfer and high-resistance insulation.

author: bsw_m
author_rank: Frequent Contributor
timestamp: May 21, 2022, 12:35:47 pm
content: I has measure diameter of glass insulated cast microwire from 100 MegaOhm resistor.Wire without insulation: 2umWire with glass insulation: 14umSorry now I cannot take the microwire photo from my microscope when I don't have the photoattachment for my microscope.P.S.I try take photo from eyepiece with phone camera. Quality not good, but..625x magnification.

author: TimFox
author_rank: Super Contributor
timestamp: May 21, 2022, 02:09:54 pm
content: Quote from: leighcorrigall on May 20, 2022, 10:03:13 pmBefore I retired, we used Shell DialaTMtransformer oil for insulating high-voltage supplies.So far as I could tell, it was basically pure motor oil, with BHT (or similar) added to retard oxidation.Butylated hydroxytoluene is an anti-oxidant, whose use in food is controversial.(For high-voltage purposes, it was necessary to pump a vacuum on top of it to remove bubbles.)