Author Topic: DIY Low EMF cable and connectors  (Read 82126 times)

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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #225 on: July 12, 2018, 02:22:13 pm »
Quote
The seller left a tag on the wire indicating the *signal direction*. When measuring low level voltage, shall I wire the cable with regard to the signal direction sign?

 :popcorn: Sounds like audiofoolery to me  :-DD
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Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #226 on: July 12, 2018, 03:26:07 pm »
I guess so...
Couldnt expect the difference between *directions*.

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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #227 on: July 12, 2018, 06:06:41 pm »

Nanovolt DIY cables anyone?
Finally got nanovolt-grade connectors.



There are lots of parts per each.



Conductors are non-plated UNC C18700 copper, insulator is PEEK.



Aren't they pretty?



LEMO P/N are EVP.1S.304.CLY for panel receptacle and FVN.1S.304.CLYC52Z for plug.
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Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #228 on: July 13, 2018, 12:28:00 am »
These copper are leaded so are easy for soldering, look nice.

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Offline HighVoltage

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Re: DIY Low EMF cable and connectors
« Reply #229 on: July 13, 2018, 08:52:56 am »
Original LEMO connectors are always so beautiful.

TiN
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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #230 on: July 13, 2018, 11:10:42 am »
Sure, it's LEMO  ;D.

I plan to build few cables for sale to fellow nuts :) I think i'd need just 4-5 connectors for my uses.
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Offline babysitter

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Re: DIY Low EMF cable and connectors
« Reply #231 on: July 13, 2018, 09:15:28 pm »
Quote
The seller left a tag on the wire indicating the *signal direction*. When measuring low level voltage, shall I wire the cable with regard to the signal direction sign?

 :popcorn: Sounds like audiofoolery to me  :-DD

Of course there is no integrated electron sorting device inside the cable, but you might in some cases *want* a direction marking on a cable. If its part of a big fat nest of the electronics bird where you want to pluck out the right end of the right cable. A coworker pointed me in noting down the position of cable markings, like assemby 1 is in the direction of the first character of cable marking, assy 2 in the direction of the last character.

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Offline retroware

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Re: DIY Low EMF cable and connectors
« Reply #232 on: August 05, 2018, 02:34:42 pm »
I was wondering what followers of this thread think of the results presented in this paper:

https://doc.xdevs.com/doc/Fluke/appnotes/nf_ncsl02.pdf

The authors were trying to verify the linearity of the Fluke 720 KVD and as such were quite concerned about EMFs due to cabling. They tried all sorts of combinations and basically concluded that tinned stranded wire was about as good as it gets.  With respect to lugs, again it didn't seem to really matter whether they were tin or gold, or even whether they were used at all.

 

Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #233 on: August 06, 2018, 10:24:00 am »
I was wondering what followers of this thread think of the results presented in this paper:

https://doc.xdevs.com/doc/Fluke/appnotes/nf_ncsl02.pdf

The authors were trying to verify the linearity of the Fluke 720 KVD and as such were quite concerned about EMFs due to cabling. They tried all sorts of combinations and basically concluded that tinned stranded wire was about as good as it gets.  With respect to lugs, again it didn't seem to really matter whether they were tin or gold, or even whether they were used at all.

So the control of the temperature and wind play the most part, regardless whatever fancy cable in use.

My lab seems not controlling temperature well, to resolve 0.1ppm is not easy.
 

Offline VK5RC

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Re: DIY Low EMF cable and connectors
« Reply #234 on: August 06, 2018, 12:04:00 pm »
I was wondering what followers of this thread think of the results presented in this paper:

https://doc.xdevs.com/doc/Fluke/appnotes/nf_ncsl02.pdf

The authors were trying to verify the linearity of the Fluke 720 KVD and as such were quite concerned about EMFs due to cabling. They tried all sorts of combinations and basically concluded that tinned stranded wire was about as good as it gets.  With respect to lugs, again it didn't seem to really matter whether they were tin or gold, or even whether they were used at all.
Thanks for the interesting read. :-+
I can't help but think - this paper is coming out of Fluke's Voltage Metrology Laboratory, some of their worst cables are certainly better than my my best! I suspect a whole lot of other issues that plaque the lower level volt-nut 'trainees' (like me) like earth loops, mains/computer interference/ pick-up etc etc  they have solved years ago.
Robert
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Offline ap

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Re: DIY Low EMF cable and connectors
« Reply #235 on: August 06, 2018, 01:53:18 pm »
Own measurements have shown that the plating (tin versus gold) does not make a measureable difference (at the levels discussed here), always provided copper is used as the base material. Gold has additional advantages of course.
Brass e.g. used for the spade material is making a difference though, you do see differences.
« Last Edit: October 19, 2018, 10:47:12 pm by ap »
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Offline BradC

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Re: DIY Low EMF cable and connectors
« Reply #236 on: October 19, 2018, 04:05:57 pm »
Maybe these will work: http://www.surplussales.com/Connectors/banana.html

Look on the page for "Gold Binding Post"



Don't know anything about them, haven't cut one open, but worth a look.

John

Just a late update, but they are out of these binding posts. I got some of these however :


They are really nicely plated, but after attacking one with a file, they are definitely brass underneath.

(edit) Just had some more land, and I cross checked the UPC code on the packet.
UPC is the same as these : https://www.digikey.com/product-detail/en/pomona-electronics/3750-0/501-1331-ND/736538, and the FSCM seems to be a match too.
So they must be similar to the gold plated brass Pomona.
« Last Edit: November 02, 2018, 11:57:27 am by BradC »
 

Offline balage

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Re: DIY Low EMF cable and connectors
« Reply #237 on: September 10, 2019, 07:26:54 am »
Sorry for the solicitation, but is here anybody want to buy those LEMOs for the nanovoltmeter?

Those can join here:
https://www.eevblog.com/forum/metrology/buying-low-thermal-emf-lemo-connector-for-nanovoltmeter-(344202182)/msg2670537/#msg2670537
 

Offline mrk

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Re: DIY Low EMF cable and connectors
« Reply #238 on: March 14, 2021, 08:59:37 pm »
Has annyone though about using Type U(Copper+Copper) thermocouple connectors? Those are cheap and I would expect them to be optimized for measuring low voltages.
 

Offline doktor pyta

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Re: DIY Low EMF cable and connectors
« Reply #239 on: April 16, 2021, 10:34:17 pm »
Just cut Pomona 1693-12-0 low EMF  spade lugs.



I was expecting crimped connections, but saw soldering.
I've tried to compare the melting point of the solder against Pb60Sn40.
I observed no difference.
So rather not cadmium-based.

The solder joint is surrounded by thick plastic barrel.
« Last Edit: April 17, 2021, 09:36:20 am by doktor pyta »
 
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Offline 1audio

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Re: DIY Low EMF cable and connectors
« Reply #240 on: April 16, 2021, 11:08:20 pm »
Having gone that far can you take a file to the spade and confirm its copper, if it actually is? Otherwise its a questionable value indeed.

They could argue that you use them in pairs and all the metal to metal junctions will cancel.
 

Offline doktor pyta

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Re: DIY Low EMF cable and connectors
« Reply #241 on: April 17, 2021, 12:05:16 am »
OK.

It's hard to have the colors right.
I'm pretty sure it is true 3 layer structure: copper, silver, gold.
« Last Edit: April 17, 2021, 09:34:17 am by doktor pyta »
 
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Offline JohnG

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Re: DIY Low EMF cable and connectors
« Reply #242 on: April 19, 2021, 01:36:50 pm »
Usually gold is not plated directly on copper because the copper will diffuse into the gold. A barrier metal is used to prevent this, and nickel is the most common one. I think sometimes more expensive metals may also be used, like rhodium.

So, the silvery layer is most likely nickel. If you want to test, hang the lug by a thin thread, and see if you can deflect it with a high energy (rare earth) magnet. If so, the plating is almost certainly nickel.

Cheers,
John
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Offline doktor pyta

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Re: DIY Low EMF cable and connectors
« Reply #243 on: April 19, 2021, 02:15:36 pm »
Good point.
The spade lug is attracted by the neodymium magnet indeed.

I'm also not sure about the solder used.
I've made nanovoltmeter cable using Pb60SN40 solder and these two spade lugs.

I cannot get the EMF voltage less than 300nV even after reaching thermal equilibrium.
When I test original cable with spade lugs by Pomona o get approx 30nV.

I've never found any info if there is cadmium in the Pomona product.
Any suggestion how to determine it using simple methods?

Online beanflying

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Re: DIY Low EMF cable and connectors
« Reply #244 on: April 19, 2021, 02:26:39 pm »
You cant necessarily use magnetism to determine a material. Brass and most Copper alloys are weakly magnetic to modern Strong magnets.

That said some of the ELectroplaters I had as customers way back when did electrical and gold decrotive work and it was a prep layer before gold but part of that was a cost thing as a thinner coating could be used.
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Offline antintedo

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Re: DIY Low EMF cable and connectors
« Reply #245 on: April 19, 2021, 06:29:19 pm »
Datasheet lists the base material as copper alloy 110, which is the ordinary type electrolytic copper.

Quote
I've never found any info if there is cadmium in the Pomona product.
Any suggestion how to determine it using simple methods?
Consider ordering a spectroscopic analysis from a lab that does water quality testing, they are pretty cheap.

Quote
I cannot get the EMF voltage less than 300nV even after reaching thermal equilibrium.
I would look into the construction of the leads first. Copper wire strands should lay flat to maximize overlap and thermal conduction, solder layer should be as thin as possible.
If you are willing to try exotic solders, pure indium is the most accessible thing and has about 5x lower TEMF than regular solder. SMDIN100 from Chipquik.
I had good results with Sn81Bi19 (or rather Sn79Bi21 at room temp), but it has to be alloyed from base metals as nobody sells it.
 
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Offline jonpaul

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Re: DIY Low EMF cable and connectors
« Reply #246 on: April 19, 2021, 07:54:33 pm »
We bought many gold plated banana jumper leds in Germany decades ago.

All have residual EMF ~ 1-3 uV.

May still be available

Jon
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Offline JohnG

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Re: DIY Low EMF cable and connectors
« Reply #247 on: April 20, 2021, 02:15:58 pm »
You cant necessarily use magnetism to determine a material. Brass and most Copper alloys are weakly magnetic to modern Strong magnets.

A small (about 10 mm diameter, 5 mm thick, NIB) magnet will not noticeably attract high purity piece of copper or brass. I learned about this trick from an engineer who worked on MRI development. It will easily and unmistakably attract something with a thin nickel plate, which is used in the vast majority of gold-plated copper, precisely because you can use a much thinner gold plate. Otherwise, you need a much thicker and more expensive gold plating that very few are willing to pay for, unless they absolutely feel they need it.

Note that I specifically said attract here, not move. If something is magnetic, or paramagnetic, the force is attractive.

Brass is another story. Lots of brass has some iron content, especially cheap brass, because they melt a lot of scrap, and they are not going to spend a lot of money extracting every steel nail, screw, or hinge pin from the pile of scrap. This was a sad discovery by my MRI colleague, who discovered that hundreds of brass machine screws used in an MRI were magnetic. He learned to test them by laying them on a flat surface and seeing if a magnet would make them roll across the surface. The ones that did were not used.

It is true that copper has a non-zero magnetic moment. A much stronger effect is the eddy currents induced by relative motion of the copper and magnet, but this can be alleviated by moving the magnet or copper piece very slowly.

Cheers,
John

Edit: fixed a typo
« Last Edit: June 01, 2021, 02:45:23 pm by JohnG »
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Online leighcorrigall

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Re: DIY Low EMF cable and connectors
« Reply #248 on: June 01, 2021, 01:10:17 pm »
Maybe these will work: http://www.surplussales.com/Connectors/banana.html

Look on the page for "Gold Binding Post"



Don't know anything about them, haven't cut one open, but worth a look.

John

Just a late update, but they are out of these binding posts.

...


FYI, the seller responded to my recent inquiry. They are not sold out.

"I have about 800 remaining in stock. These are 75+ years old. I do not have a factory spec but would guess that the base is brass because that was the case 99% of the time back then. It was harder than copper of the day and the threads held up better. Typically the gold plate thickness is 50-75 micro inches, 20-40 times thicker than what is typically used in current electronics. These were government specified and used parts. I have no additional information."
 
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