Author Topic: Investigation on ...  (Read 12662 times)

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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #25 on: December 04, 2016, 11:45:18 am »
There is no need to measure humidity if the case is fully filled with LS230, Galden does not absorp water. And changes in pressure will be very low, presumably to low to measure it with BME280. Furthermore BME280 will not like the contact with Galden, especially its humidity sensor. To integrate a really suitable pressure sensor is a lot of effort.
The only thing I could consider is some kind of pressure membrane made of CuBe that can balance small pressure differences between inside and outside, but that would be a bigger effort too.

The knowledge why I use Galden is some ip that I can't share with you, so you have to take it as it is.
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Offline SeanB

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Re: Investigation on ...
« Reply #26 on: December 04, 2016, 12:14:36 pm »
I would guess because it is very inert, contains no moisture and is not going to react with the components of the casing and the resistor chemically, and will only have a constant effect on AC characteristics as it is a dielectric liquid.

SF6 would probably also work there, but is a lot more difficult to handle. Would require a fill port to use it, and a vacuum proof seal as well.

I guess you do the fill simply by using some pretinned case lips, a tinned cap edge and solder without flux, by simply immersing in the hot liquid, after filling the case with cold liquid and placing the lid on. Solder melts below the boiling point, and then the lid is sealed perfectly with no gas bubbles inside, and with a hermetic seal as well.
 

Offline zlymex

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Re: Investigation on ...
« Reply #27 on: December 05, 2016, 12:16:46 am »

Worth noting that the 4-wire feedthrough for the main resistor is actually not necessary. Simply calculate how much the very short resistor copper wires affect the total temperature coefficient.

The SR104 uses 2-wire feedthrough but there is also 15 cm 2-wire cabling from the feedthrough to the binding posts (2w/4w interchangeability was important at the time it was designed).
Agreed.
That 30cm(15cm * 2) is only 10mR in resistance(1mm2 is assumed), which is only 1ppm of the total resistance, and the variation of which can be safely ignored.
 

Offline zlymex

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Re: Investigation on ...
« Reply #28 on: December 05, 2016, 12:50:16 am »
There is a lid on top and some feedthrough capacitors at the sides.
Very interesting. Are those feedthrough capacitors be soldered to the case?
 

Offline babysitter

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Re: Investigation on ...
« Reply #29 on: December 05, 2016, 06:14:58 am »
Hi Branadic,

I too was thinking about a prefilled solderable (Otto Schubert) enclosure and Novec 7100 for a board, I think I also mumbled about it on volt-nuts or here. For pressure/expanson relief, I was thinking about a nickel bellow (e.g. from servometer mfg.) but someone pointed me to the "pressure capsule" (Druckdose...) used in liquid-filled thermostats, any old fridge might give you one.
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Offline Gyro

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Re: Investigation on ...
« Reply #30 on: December 05, 2016, 10:15:57 am »
I would guess because it is very inert, contains no moisture and is not going to react with the components of the casing and the resistor chemically, and will only have a constant effect on AC characteristics as it is a dielectric liquid.

SF6 would probably also work there, but is a lot more difficult to handle. Would require a fill port to use it, and a vacuum proof seal as well.

I guess you do the fill simply by using some pretinned case lips, a tinned cap edge and solder without flux, by simply immersing in the hot liquid, after filling the case with cold liquid and placing the lid on. Solder melts below the boiling point, and then the lid is sealed perfectly with no gas bubbles inside, and with a hermetic seal as well.

Isn't a sealed rigid looking container, completely liquid filled, going to subject the contents to very large pressure changes with temperature? That sounds like something that could impact drift.

Totally inert (Noble) gas filling sounds a safer bet, even if it does involve fill ports. These wouldn't be difficult to arrange, taking a tip from the refrigeration industry. A couple of thin copper tubes soldered into the case, fill through one, exhaust through the other. Crimp and solder seal the exhaust one and then crimp the inlet one, remove the gas supply and solder seal that too. Argon would be the cheapest and most readily available option.

Best Regards, Chris
 

Offline SeanB

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Re: Investigation on ...
« Reply #31 on: December 05, 2016, 07:09:01 pm »
Galden is very non reactive, as it is a fluorinated hydrocarbon. It takes a lot of energy ( like a high current arc) to break it down.

SF6 however is around the most stable compound you can get, it will not decompose under any condition short of having lightning hit it. Dangerous though as it is invisible, has no odour and displaces oxygen in the ambient with a leak.
 

Online Kleinstein

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Re: Investigation on ...
« Reply #32 on: December 05, 2016, 07:45:24 pm »
If really 4 wire feed troughs are needed, depends on the resistor value. For a 10 mOhms resistor you will definitely need it, at 1 M you don't. Also the wires at the feed through can be thin and maybe something else than copper.

For a constant pressure, it might be good to have a little gas left. If this is just the vapor of the liquid used one would just follow the vapor pressure curve. So stable pressure at stable temperature.
 

Offline branadicTopic starter

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Re: Investigation on ...
« Reply #33 on: December 07, 2016, 07:25:22 pm »
Currently the copper parts are on their way to me... Lids are finished and the surface of the copper parts blasted with glas beads. Thanks to Hugo Lindner, he did a very great job, didn't he?  :-+
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Offline Andreas

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Re: Investigation on ...
« Reply #34 on: December 07, 2016, 07:46:19 pm »
Hello,

where do I get this golden christmas tree?  :-+

with best regards

Andreas
 

Offline acbern

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Re: Investigation on ...
« Reply #35 on: December 08, 2016, 12:00:14 pm »
Nice units. Did not know Hugo Lindner, bookmarked. What did you have to pay appr. per piece? I feel I am often ripped off by my mechnical guy.

Secondly, VAR resistors are not that easily available from stock, standard Z-foil are. Why not use these?
 

Offline TiN

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Re: Investigation on ...
« Reply #36 on: December 08, 2016, 12:26:21 pm »
Sorry, can't help it. That face with triple holes looks too much like :

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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #37 on: December 09, 2016, 07:37:30 pm »
Gift giving  :-+
The parts arrived today, what beauties. One of them had a date with some feedthrough caps and a resistor. No, nothing dirty just a fitting  ::)
Next step, Ni/Au finish of the surface!
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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #38 on: January 11, 2017, 07:39:55 pm »
Surface is now processed with nice looking Ni/Au.
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Offline cncjerry

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Re: Investigation on ...
« Reply #39 on: January 14, 2017, 05:06:53 am »
you gave it away too soon...  I was going to say "a snow cone maker."

Nice work by the way.
 

Offline Dubbie

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Re: Investigation on ...
« Reply #40 on: January 14, 2017, 07:17:25 am »
Did you get those cast or just machined from solid bar? That's a pricy piece of metal!


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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #41 on: January 14, 2017, 10:50:10 am »
Quote
Did you get those cast or just machined from solid bar? That's a pricy piece of metal!

They are maschined from solid copper bars I had laying around for years. But they are smaller then they look. ;)
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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #42 on: August 20, 2018, 07:14:11 pm »
The first 100R - PT1000 combination is almost done. Need to solder the lid and fill the case with fluid.
Also finished two assemblies with 1k - 33k NTC combination for a forum member. As I only need another 2 cases for 1k and 10k there are 5 units left. Someone interested in them?

-branadic-
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Offline Magnificent Bastard

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Re: Investigation on ...
« Reply #43 on: August 20, 2018, 08:08:25 pm »
The first 100R - PT1000 combination is almost done. Need to solder the lid and fill the case with fluid.
Also finished two assemblies with 1k - 33k NTC combination for a forum member. As I only need another 2 cases for 1k and 10k there are 5 units left. Someone interested in them?

-branadic-

Beautiful!
 

Offline IRFP

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Re: Investigation on ...
« Reply #44 on: August 20, 2018, 08:44:01 pm »
Good evening,
Superb achievement! :-+
These are capacitors crossed? There are simple, non-capacitive and hermetic feedthroughs. Here is the manufacturer link: https://7doloy.micronor.fr/produits/#traversees-isolantes-unitaires
Pour ce qui est de l’huile, moi j’ai utilisé pour stabiliser en température mon LM399 de l’ISOVOLINE de chez TOTAL, c’est de l’huile diélectrique pour transformateur HT/BT.
Attention à l’étanchéité de la chambre, cette huile est extrêmement fluide.
 

Offline branadicTopic starter

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Re: Investigation on ...
« Reply #45 on: August 22, 2018, 08:08:34 pm »
Thanks for the flowers.
Yes these are low value feedthrough capacitors. Hermetic feedthroughs are nice, but my problem is, I don't speak french and their website seems to be very limited with information in an international language.  ;D

-branadic-
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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #46 on: August 23, 2018, 06:12:14 pm »
Seems like the five units found two new owners :)

-branadic-
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Offline TiN

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Re: Investigation on ...
« Reply #47 on: August 24, 2018, 04:04:16 am »
I'd be interested in one to run to do 8508/01s comparison, if you have more for sale. My main interest is in 10/100/1K values, as I have 1R/10K and highers to better standards already.  :)
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Offline branadicTopic starter

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Re: Investigation on ...
« Reply #48 on: August 24, 2018, 08:02:47 am »
You are to late boy, they are all sold.

-branadic-
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