Author Topic: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?  (Read 12457 times)

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Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #25 on: November 13, 2017, 04:30:02 am »
I have some prototypes of the 4-post straps coming from OSHPARK.  They are just like the 2-post straps, except are stretched 0.75" in order to reach the second set of jacks.

If they turn out OK and I order larger quantities from China, I might do them on 1mm stock instead of 0.8 mm in order to make the longer fingers a little more rigid.
 

Offline Cerebus

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #26 on: November 13, 2017, 12:18:03 pm »
..., and lots of thermal mass.

Well that's one of those things that cuts both ways. A small thermal mass reaches equilibrium quickly, but that perforce implies that it all can be knocked out of equilibrium quickly. A large thermal mass can sometimes act as useful thermal lag, and function as a low pass filter on any thermal changes that do occur. Which is going to be best is going to depend on the local thermal environment and its stability on timescales similar to the thermal time constant of your short.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Offline tszaboo

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #28 on: November 13, 2017, 01:21:38 pm »
Ready made, 3 boards and you can do 1 with 4 bananas and 2 ea with 2 bananas. https://oshpark.com/shared_projects/yOAPbUZF

Can you tell me the part number + manufacturer of those banana connectors? I've been looking for these for ages.
 

Offline sarel.wagner

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #29 on: November 13, 2017, 03:47:27 pm »
Hi, I could only get with M3 stud from RS Electronics:
Multi Contact, 4mm Banana Plug, Gold Plated, 50A

Part details
Manufacturer Multi Contact
Mfr. Part No. 22.1055
https://media.rs-online.com/t_large/F2622028-01.jpg

Offline Cerebus

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #30 on: November 13, 2017, 03:58:00 pm »
Just to point out that Multi-Contact have quite a range of 4mm studs, well worth a look at the catalogue if it's something you ever have a need for.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline VacuumindedTopic starter

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #31 on: November 13, 2017, 04:40:51 pm »
Hi, I could only get with M3 stud from RS Electronics:
Multi Contact, 4mm Banana Plug, Gold Plated, 50A

Part details
Manufacturer Multi Contact
Mfr. Part No. 22.1055
https://media.rs-online.com/t_large/F2622028-01.jpg
 

Offline casinada

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #32 on: November 13, 2017, 11:58:31 pm »
 :) They cost around $70 US Dollars for the Keithley parts. The Pomona Shorting bar costs around $3.30 US Dollars.  :)
« Last Edit: November 14, 2017, 12:19:38 am by casinada »
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #33 on: November 14, 2017, 12:21:39 am »
:) They cost around $70 US Dollars

Ouch!   My 4-wire ones should run $2-$3 each.   I'm shooting for $10 for 10 of the two wire ones.  I might do a combo pack of 6 x 2-wire and 4 x 4 wire ones for $10.
 

Offline tszaboo

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #34 on: November 15, 2017, 02:52:01 pm »
Hi, I could only get with M3 stud from RS Electronics:
Multi Contact, 4mm Banana Plug, Gold Plated, 50A

Part details
Manufacturer Multi Contact
Mfr. Part No. 22.1055
https://media.rs-online.com/t_large/F2622028-01.jpg
Thanks. But now I've found the Multi-contact 22.1054 which is gold plated, and metric, and 1/3 the price of the keystone.
Anyway, If you are still looking for banana shorting, I've used the Pomona MDP-S before. Which is only shorting 2 terminals, but it is stackable, so 3 of them should short your meter, if the distance is standard.
 

Offline macboy

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #35 on: November 15, 2017, 03:20:09 pm »
Hi, I could only get with M3 stud from RS Electronics:
Multi Contact, 4mm Banana Plug, Gold Plated, 50A

Part details
Manufacturer Multi Contact
Mfr. Part No. 22.1055
https://media.rs-online.com/t_large/F2622028-01.jpg
Thanks. But now I've found the Multi-contact 22.1054 which is gold plated, and metric, and 1/3 the price of the keystone.
Anyway, If you are still looking for banana shorting, I've used the Pomona MDP-S before. Which is only shorting 2 terminals, but it is stackable, so 3 of them should short your meter, if the distance is standard.
Look carefully at the datasheet for the Multi-contact 22.1054 ... In Newark's system the contact material is "Copper" but the datasheet says "CuZn" which is brass. That's probably not what you want.
 

Offline tszaboo

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #36 on: November 15, 2017, 04:18:43 pm »
Hi, I could only get with M3 stud from RS Electronics:
Multi Contact, 4mm Banana Plug, Gold Plated, 50A

Part details
Manufacturer Multi Contact
Mfr. Part No. 22.1055
https://media.rs-online.com/t_large/F2622028-01.jpg
Thanks. But now I've found the Multi-contact 22.1054 which is gold plated, and metric, and 1/3 the price of the keystone.
Anyway, If you are still looking for banana shorting, I've used the Pomona MDP-S before. Which is only shorting 2 terminals, but it is stackable, so 3 of them should short your meter, if the distance is standard.
Look carefully at the datasheet for the Multi-contact 22.1054 ... In Newark's system the contact material is "Copper" but the datasheet says "CuZn" which is brass. That's probably not what you want.

"Lantern-style machined from brass and gold plate. The lantern spring is drawn from copper alloy sheet to provide constant contact pressure and a low resistance."
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #37 on: November 15, 2017, 11:00:48 pm »
OSHPARK has the prototype straps off to the board fab.  They should be back around Dec 8.
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #38 on: November 27, 2017, 07:29:36 pm »
OSHPARK has the prototype straps back from the fab.   They should be here in a few days.  If they check out, I'll send the boards off to China for some quantities.  I did both two post and four post straps.
 

Online beanflying

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #39 on: December 01, 2017, 12:47:07 am »
Got a little stash of these arrived today. 1mm Gold flashed Brass based on slightly magnetic and double spacing 38mm or 1 1/2"
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Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #40 on: December 01, 2017, 12:52:10 am »
I'd be a little concerned about thermal EMF issues with brass / steel.

OSHPARK has shipped mine.  They should have been here today but did not arrive.
 

Online beanflying

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #41 on: December 01, 2017, 12:55:58 am »
Steel certainly. Brass a little bit. I do have a little bit of Silver Bar left from making High powered batteries but my 'source' of that is no more.
Coffee, Food, R/C and electronics nerd in no particular order. Also CNC wannabe, 3D printer and Laser Cutter Junkie and just don't mention my TEA addiction....
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #42 on: December 01, 2017, 11:20:07 pm »
I got the boards back from OSHPARK...  they did not have any copper on them!   Grrrrr...
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #43 on: December 02, 2017, 05:27:49 am »
I got the boards back from OSHPARK...  they did not have any copper on them!   Grrrrr...

It turns out the problem was the polygon boundary line was set to 0 width which caused OSHPARKs .brd processor to time out when generating the Gerbers.  Setting the width to 0.001" fixed it.

The HP3458A has a slightly wider horizontal banana spacing than the vertical spacing and the 4-post strap was rather tight when inserted from the top of the banana jacks.  It fit fine when inserted from the sides.  I tweaked the spacing.  I also added a row of via stitching down the middle of the strap.
 

Offline MiDi

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4-wire short - DIY
« Reply #44 on: January 01, 2018, 07:22:42 pm »
Nice, I did not recognize this topic when I finally designed my 4-wire short:



I thought about modifying this for the larger space 4-wire terminals (HP 3457A, 3458A, ...), but decided to not do this simple modification, because a simple PCB screwed down should give lower emf and lowers the price.
Is there already a PCB-design for this?

My design idea (easy to modify for 19x19mm):
« Last Edit: January 01, 2018, 07:26:37 pm by MiDi »
 

Offline texaspyro

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #45 on: January 01, 2018, 07:43:01 pm »
I just got in the new shorting strap PCBs from OSHPARK.  There is a 4 wire and two wire version.  I'm not going to be selling the boards directly but you can get them here for cheap:

Four wire:
https://oshpark.com/shared_projects/j4Htt3KM

Two wire:
https://oshpark.com/shared_projects/QBeVyK9X

You should use the 0.8 mm board thickness / 2oz copper option.  If you need more than three boards it can be cheaper to download the Eagle .brd file and send it to dirtypcbs.com...  specify ENIG gold finish.
« Last Edit: January 02, 2018, 01:52:33 am by texaspyro »
 
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Offline worsthorse

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Re: Copper binding post shorting straps for low thermal EMF-- Alloy/tempering?
« Reply #46 on: November 15, 2019, 06:10:34 am »
bump
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