# Old switch gear what can i expect to find in something like this



## Matteo23 (Oct 17, 2022)




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## Yggdrasil (Oct 18, 2022)

Matteo23 said:


> View attachment 52700


It would be nice with more information.
Edit for spelling


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## Matteo23 (Oct 18, 2022)

Any help with identifying what I have here would be great


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## Yggdrasil (Oct 19, 2022)

Matteo23 said:


> Any help with identifying what I have here would be great


As we say, we need more information.
Where did it come from and so on.


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## Matteo23 (Oct 19, 2022)

I purchased a bunch of this from someone on fb market place I don't have any info on it


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## Matteo23 (Oct 19, 2022)

More pictures


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## Yggdrasil (Oct 19, 2022)

Well then it is anyones guess.
If there are values it will be the contact points.
Cut off one and try to dissolve in HCl.
If the point itself dissolves, no value.
If the points remain dissolve in Nitric.
Take a drop of the solution and drop in a grain of salt.
If it becomes white, it is Silver, if not test with Stannous.
If it do not dissolve in Nitric.
Pour off the solution and add fresh HCl and add a drop of Nitric in it and try to dissolve in AR.
I may need some heating.
Then test with stannous.

Remember we are talking about milliliters of liquids here.


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## orvi (Oct 19, 2022)

As it was said above correctly by Yggdrasil, value comes from actual contact points, which are miniscule here (at least if I see them correctly). Try to dislodge only the contact point for testing if possible - pry it or scratch it off the carrier if possible. This way, you does not cross-contamine the testing sample with plenty of base metal carrier. But if it can´t be done, you can test anyway 

Most straightforward is to directly test with nitric acid. Undiluted, 53 or 65% stuff is OK for the test. Put one or two dislodged contact points into some vial/test tube or anything from glass, transparent and with volume of few mL. Drop few drops of acid onto the material and observe the reaction. 

Contact points are usually made from silver alloys or pure silver. For small contacts, it is most often pure silver or "hard silver" - that is AgCu alloy. Less common, but not uncommon for these small contacts are AgCd alloys. 
Silver is colorless in nitric solution, and does produce quarky white heavy precipitate of AgCl if you drop brine solution into the test vial. Blue colouration is copper, blueish-light green could be nickel.

Small contact points are much less often made with AgPd alloys - this time, contact point will react only very slowly with nitric acid at room temperature, and you will observe reddish-brown colouration appearing near the surface of the point in nitric acid. With heating contact point will dissolve completely leaving very dark red-brown solution.

Less often than AgPd, small contacts could be made from gold alloys. Mainly in old apparatus, for very fine applications. Alloys are usually AuAg25-30, Au70AgNi5Cu, AuNi5 or similar types. These, you will distinguish relatively easily, as they most often have some yellow tinge when cut and fresh metal is seen. Not typical yellow 24k gold colour, but more pale yellowish-silvery colour. 

These alloys will not dissolve in nitric acid, and just AuNi5 types will dissolve unwillingly and slowly in AR.
Very rarely, contact points could be made from Pt alloys. I encountered PtIr10 and PtRh10 alloys in very special MIL class old soviet relays. But that was it, two times in my refining career 

Apart form precious metals, contact points can be sintered from various base metals and even some precious metals. You can recognize them easily as they crumble when cut. These are very often made from tungsten with addition of silver, or AgC contact points are fairly common. But most of the times, they are used for larger contact points than few mm, manufacture of very small contacts from these sintered matters is cumbersome due to crumbling.


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## Martijn (Oct 19, 2022)

my best guess: telephone patch panel. one contact to detect the plug is in, one contact for the actual communication.

so, the comm. contact could have pm's.
as said, test it.


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## BlackLabel (Oct 19, 2022)

These parts are jacks for microphones or headsets. There are no real relay contacts inside. Maybe the contact surface is plated by some precious metal.


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## Martijn (Oct 19, 2022)

The black oxide makes me suspect silver plating. Test with a bit of bleech and see if it turns black.


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