Electronics > Metrology

Precision Resistors - General Thread

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leighcorrigall:
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
- applications

Seeing as there is interest in building environmental test enclosures https://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=sharing

EDIT: 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!   :-/O

That's it for now.

TiN:
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/ .

veedub565:
Maybe a little OT but I'd be interested to hear peoples thoughts on this source of lab standard precision resistors

https://www.ebay.co.uk/itm/331951651645?hash=item4d49dc3b3d:g:VUwAAOSwLfNa2EXb

leighcorrigall:

--- Quote from: veedub565 on July 06, 2021, 12:59:07 pm ---Maybe a little OT but I'd be interested to hear peoples thoughts on this source of lab standard precision resistors

--- End quote ---

You could also try https://www.eevblog.com/forum/metrology/teardown-standard-resistors/?all.

veedub565:
Thanks for the link, there is a lot of detailed information in that thread.

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