Author Topic: Teardown: Standard Resistors  (Read 75828 times)

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Offline wolfy007

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Re: Teardown: Standard Resistors
« Reply #225 on: July 29, 2020, 04:18:02 pm »
Just had this Fluke 750A Reference Divider open on my bench for a look, so took a few quick pictures.
« Last Edit: August 05, 2020, 02:10:08 pm by wolfy007 »
 
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Offline doktor pyta

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Re: Teardown: Standard Resistors
« Reply #226 on: August 04, 2020, 08:47:10 pm »
I found a mechanically damaged standard so I tore it down and saw something interesting.

It was made in Poland in the seventies by the 'Inco' factory.
It is 0.1 ohm, 1W in air/ 3W in oil. tolerance 0.01% Manganin.



It is built as parallel connection of two coils wound in opposite directions.
I measured the inductance and obtained 200nH.





 
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Online TimFox

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Re: Teardown: Standard Resistors
« Reply #227 on: August 04, 2020, 08:50:58 pm »
Can you tell what insulation was used?  I know that cotton and silk were common, years ago, but I don’t know what was preferable in oil.
 

Offline doktor pyta

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Re: Teardown: Standard Resistors
« Reply #228 on: August 04, 2020, 09:06:26 pm »
First of all the manganin tape is coated with laquer or enameled.
It is wound on an aluminum bobbin covered with some kind of insulating paint.
The twine is used only as a spacer and mechanical holder for the manganin tape.

Online HighVoltage

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Re: Teardown: Standard Resistors
« Reply #229 on: August 05, 2020, 08:24:35 am »

It is wound on an aluminum bobbin covered with some kind of insulating paint.


Interesting resistor, I have never heard of that company.

Are you sure it is an aluminum bobbin?
May be it is an insulator made of Aluminum Oxide?

What is its reading, is it still stable?
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline doktor pyta

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Re: Teardown: Standard Resistors
« Reply #230 on: August 05, 2020, 02:02:10 pm »
Yes, double checked that. The bobbin is for sure made of Al, but the winding has some free space to move.
Value measured: 0,0999975 ohm  (setup uncertainty approx. +/-30ppm).
The insulator looks rather like enamel which is sometimes used on cooking pots :)

Online HighVoltage

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Re: Teardown: Standard Resistors
« Reply #231 on: August 05, 2020, 02:07:43 pm »
That seems to be a very nice Manganin resistor, they usually have 10ppm/K temperature drift.
May be you can find a nice new housing for this resistor.

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Offline doktor pyta

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Re: Teardown: Standard Resistors
« Reply #232 on: September 30, 2020, 11:18:51 am »
New puppy in the lab.


R4030-M1 (Р4030-м1) made in USSR wirewound 1G ohm standard. Umax 2500V
Tol 0.01%, TC in my case: alpha: 8ppm/C; beta: 0 (quoting individual specs sheet).


It is made as series connection of two microwire hermetic resistors (bigger than shown on a picture) and a selected resistor or potentiometer.



« Last Edit: October 06, 2020, 07:52:51 pm by doktor pyta »
 
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Offline NANDBlog

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Re: Teardown: Standard Resistors
« Reply #233 on: October 01, 2020, 01:59:06 pm »
Just had this Fluke 750A Reference Divider open on my bench for a look, so took a few quick pictures.
What's that block in the middle? PN184986
Is that a lot of TO-18 style package resistors in a block?
 

Offline Gyro

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Re: Teardown: Standard Resistors
« Reply #234 on: October 01, 2020, 04:50:41 pm »
Just had this Fluke 750A Reference Divider open on my bench for a look, so took a few quick pictures.
What's that block in the middle? PN184986
Is that a lot of TO-18 style package resistors in a block?

That's the container for the main divider resistors. It's oil filled (note the filler bolt at the end). The 'TO18 style' things are hermetic feedthoughs.
Chris

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Online antintedo

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Re: Teardown: Standard Resistors
« Reply #235 on: October 20, 2020, 05:28:53 am »
A look inside hermetically sealed Tinsley 5685A. Photo from DOI:10.1109/CPEM.2008.4574696
100 ohm variant specified at 2ppm/year and 2ppm/K.

Bifilar winding on a fiberglass bobbin with fiberglass spacers. PTFE and bakelite top cover. Paper authors point out poor design of the terminals. Joints seem to be arc welded. Selection of two wire diameters and the way wires are bent before welding makes the process very forgiving, which could indicate they use a simple method like manually pulsed TIG.
 
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Online antintedo

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Re: Teardown: Standard Resistors
« Reply #236 on: October 20, 2020, 05:55:53 am »
HRU standard from Alpha AE (now Vishay).
Specified at 0.1ppm/year (!) 0.05ppm/K. Offered for ~$10k.

Metal foil process, but without any substrate. Ceramic, hermetic, oil filled resistive element body. The element is free floating and only attached by one edge to the body.
Interesting construction details can be found in DOI 10.1109/TIM.2011.2108613, 10.1109/TIM.2018.2879997.
 
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Online MiDi

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Re: Teardown: Standard Resistors
« Reply #237 on: October 20, 2020, 04:32:09 pm »
Still waiting for the 10k  8)

For convenience with links - access to IEEE needed, but abstracts are for free:

Novel 100-Ω Metal Foil Resistor - 2011

Development and Evaluation of High-Stability Metal-Foil Resistor With a Resistance of 1 kΩ - 2015

Characterization of 1 kΩ Metal-Foil Standard Resistors and Continuing Drift-Rate Evaluation of 1 Ω and 10 Ω Standard Resistors - 2018

Quote from: Abstract from Characterization
A set of standard resistors is a key component of resistance calibration. We have been developing a series of compact superstable standard resistors that meet calibration laboratory demands. In this paper, we describe manufacturing and evaluation of 1 kΩ standard resistors. All the resistors elements are made with the “stress free bulk metal foil” technology. We found that all standard resistors show extremely small average drift rates, e.g., smaller than 10 nΩ/(Ω year) and small temperature coefficients typically around 35 nΩ/(Ω °C) at 23 °C. Moreover, continuing the evaluation of drift behavior of 1 Ω and 10 Ω standard resistors is discussed.

8x1kΩ, 1715 days eval: 3.3nΩ/Ωyr avg (-0.8 ... 5.4 max), TC a23 35nΩ/ΩK avg (-77 ... 55 max), TC b 0.83nΩ/ΩK² avg (0.0 ... 1.5 max)
*1nΩ/Ω = 1ppb = 0.001ppm
« Last Edit: October 20, 2020, 05:22:23 pm by MiDi »
 


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