Electrical contacts

[kurtak]

I added pictures

In the post with the 2 pictures the contact point upper righthand side of pic is absolutely without question a tungsten/silver contact point

The absolute dead giveaway that it is tungsten/silver is the rough surface (lines) on the "back" side of the point

ALL tungsten/silver contact points (& ONLY tungsten/silver contact points) have some sort of rough surface on the "back" side of the points commonly referred to as a "waffle pattern" --- that rough surface can ether be an actual waffle like pattern - or lines - or small dots

That is because tungsten does not make a good strong solder/braze adhesion to the point when they solder/braze the points to the bus bar --- so when they sinter/press the points they do it to create that waffle pattern on the back side of the point which gives the points a rough surface for the solder/braze to better grip/bond/adhere the points to bus bar

Because (unlike most other metals) solder/braze does not bond well with tungsten the points would fail (break free from the bus bar) as a result of the conductive heat generated by the electrical current running though them when closed so the waffle pattern on the back side of the points gives the solder/braze something to better grip/bond the points & prevent that failure

These tungsten/silver contact points come (almost) exclusively out of "hand thrown" circuit breakers (as opposed it magnetic "disconnects" &/or relays) whether they are the circuit breakers you find in you house electric panel or LARGE industrial circuit breakers --- you may (or not) also find them in other "hand thrown" switches

So any time you see that waffle pattern on the back side of the point you can be absolutely sure they are the tungsten/sliver points --- you may not always see the waffle pattern on the back when you de-solder/braze the points from the bus bar as the solder/braze may (or not) cover up the waffle pattern

So - if they come out of hand thrown circuit beakers they will "absolutely" be tungsten/silver - if they have a waffle pattern on the back they will "absolutely" be tungsten/silver

Also - tungsten is "very" brittle (as well as it is a sintered product & not an actual alloy) so if you put them in a vice & hit them with a hammer they will break (may bend "a little" before breaking) --- whereas actual silver contacts will bend a lot before breaking

Kurt

 

[kurtak]

One more note - a hand thrown circuit "breaker" is not the same thing as a hand thrown "switch"

A circuit "breaker" is designed to automatically "break" the circuit "connection" when the circuit over draws the amp/current rating of the "breaker"

A hand thrown "switch" make no such automatic break/disconnect - it is ether on - or off

Kurt

 

[kurtak]

hi ,
tungsten is not magnetic , alloys of tungsten may be like densalloy which have nickel in it.
regards

That is correct - tungsten in & of itself is NOT magnetic (though it is paramagnetic) tungsten carbide however is magnetic but that is due the nickel or cobalt in it as a binder in making the tungsten carbide

By the way, tungsten is magnetic...
contact detail from an ancient vibration transducer after nitric acid and a burner...

Those are likely tungsten carbide point - it is the nickel/cobalt in them making them magnetic - not the tungsten

Kurt

 

[kurtak]

I have found a few extremely high-end contacts in relay switches that were solid gold. They were very flat and very small. If they're the 'button' type, then they're always plated. But if you have certain critical industry boards from just the right era, the little flat contacts are solid gold. I've found them in high-end telecom boards (which also had all the PROM leg slots entirely gold-plated).

Those relay switches are very small, the boxes barely 1cm wide, and are kind of a pain to dismantle. I still have half a jar of them, because they take SO LONG to get apart. Each one had 6 tiny gold contacts inside.

Alondro - could you provide a pic of these relays

Kurt

 

[stella polaris]

Kurt, my experience is that relay boxes, with less than 1 x 1,5 cm top area, most of the times have these type of contacts Alondro taks about. I also found this type of relays were tiny copper connection bars (busbars?) had been soldered with some type of gold solder. They are quite common in steering equippment and i as well have a jar of them, waiting for a rainy day.

I love to find bords with this type of small relays. Sometimes it can be 10-12 of them on one boatrd. Black, White, Blue, Red and Yellow boxes i found gold contacts in.

 

[Alondro]

Alondro - could you provide a pic of these relays

Kurt

Here's a pic of the 3 types I have still in the jar. Took apart the few little blue and red ones already.

 

[Proffshuggarn]

In the post with the 2 pictures the contact point upper righthand side of pic is absolutely without question a tungsten/silver contact point

The absolute dead giveaway that it is tungsten/silver is the rough surface (lines) on the "back" side of the point

ALL tungsten/silver contact points (& ONLY tungsten/silver contact points) have some sort of rough surface on the "back" side of the points commonly referred to as a "waffle pattern" --- that rough surface can ether be an actual waffle like pattern - or lines - or small dots

That is because tungsten does not make a good strong solder/braze adhesion to the point when they solder/braze the points to the bus bar --- so when they sinter/press the points they do it to create that waffle pattern on the back side of the point which gives the points a rough surface for the solder/braze to better grip/bond/adhere the points to bus bar

Because (unlike most other metals) solder/braze does not bond well with tungsten the points would fail (break free from the bus bar) as a result of the conductive heat generated by the electrical current running though them when closed so the waffle pattern on the back side of the points gives the solder/braze something to better grip/bond the points & prevent that failure

These tungsten/silver contact points come (almost) exclusively out of "hand thrown" circuit breakers (as opposed it magnetic "disconnects" &/or relays) whether they are the circuit breakers you find in you house electric panel or LARGE industrial circuit breakers --- you may (or not) also find them in other "hand thrown" switches

So any time you see that waffle pattern on the back side of the point you can be absolutely sure they are the tungsten/sliver points --- you may not always see the waffle pattern on the back when you de-solder/braze the points from the bus bar as the solder/braze may (or not) cover up the waffle pattern

So - if they come out of hand thrown circuit beakers they will "absolutely" be tungsten/silver - if they have a waffle pattern on the back they will "absolutely" be tungsten/silver

Also - tungsten is "very" brittle (as well as it is a sintered product & not an actual alloy) so if you put them in a vice & hit them with a hammer they will break (may bend "a little" before breaking) --- whereas actual silver contacts will bend a lot before breaking

Kurt

@kurtak, I must honestly say that I am incredibly impressed with your knowledge, I am not kidding.
You have my full respect
/Dennis

 

[Proffshuggarn]

Here's a pic of the 3 types I have still in the jar. Took apart the few little blue and red ones already.

Thank you @Alondro for showing that picture.
I have a box full of just such, saved them because they were very difficult to open and thought that they should lie until one day I know what they are and if they have something valuable in them.
Today is that day .
Thank you , Now the gloves are put on and the box is taken out again.
/Dennis

 

[Reggy]

In the post with the 2 pictures the contact point upper righthand side of pic is absolutely without question a tungsten/silver contact point

The absolute dead giveaway that it is tungsten/silver is the rough surface (lines) on the "back" side of the point

ALL tungsten/silver contact points (& ONLY tungsten/silver contact points) have some sort of rough surface on the "back" side of the points commonly referred to as a "waffle pattern" --- that rough surface can ether be an actual waffle like pattern - or lines - or small dots

That is because tungsten does not make a good strong solder/braze adhesion to the point when they solder/braze the points to the bus bar --- so when they sinter/press the points they do it to create that waffle pattern on the back side of the point which gives the points a rough surface for the solder/braze to better grip/bond/adhere the points to bus bar

Because (unlike most other metals) solder/braze does not bond well with tungsten the points would fail (break free from the bus bar) as a result of the conductive heat generated by the electrical current running though them when closed so the waffle pattern on the back side of the points gives the solder/braze something to better grip/bond the points & prevent that failure

These tungsten/silver contact points come (almost) exclusively out of "hand thrown" circuit breakers (as opposed it magnetic "disconnects" &/or relays) whether they are the circuit breakers you find in you house electric panel or LARGE industrial circuit breakers --- you may (or not) also find them in other "hand thrown" switches

So any time you see that waffle pattern on the back side of the point you can be absolutely sure they are the tungsten/sliver points --- you may not always see the waffle pattern on the back when you de-solder/braze the points from the bus bar as the solder/braze may (or not) cover up the waffle pattern

So - if they come out of hand thrown circuit beakers they will "absolutely" be tungsten/silver - if they have a waffle pattern on the back they will "absolutely" be tungsten/silver

Also - tungsten is "very" brittle (as well as it is a sintered product & not an actual alloy) so if you put them in a vice & hit them with a hammer they will break (may bend "a little" before breaking) --- whereas actual silver contacts will bend a lot before breaking

Kurt

Thank you very much Kurt. Your replies have been vey informative and helpful. I appreciate them greatly. I actually was wondering why there was that pattern.

 

[Reggy]

Here's a pic of the 3 types I have still in the jar. Took apart the few little blue and red ones already.

 

[Reggy]

View attachment 62050View attachment 62050

Are these relays? They look like they have a switch drawing on them

 

[Proffshuggarn]

Are these relays? They look like they have a switch drawing on them

Good question @Reggy
I have no clue about that but the question I usually ask is, is there gold or something else ”fun” in them

 

[Alondro]

Thank you @Alondro for showing that picture.
I have a box full of just such, saved them because they were very difficult to open and thought that they should lie until one day I know what they are and if they have something valuable in them.
Today is that day .
Thank you , Now the gloves are put on and the box is taken out again.
/Dennis

If you don't mind dissolving the whole copper alloy arm with the little gold dots on them, then it's not too hard. But I suspect some of them might be beryllium copper because it's very hard alloy, and I hate dealing with beryllium in solution because it's so nasty and impossible to remove from the solution by any means a backyard refiner will have access to.

So I take great pains to knock off the little gold dots... which is a very slow process.

Others clearly have a yellow brass alloy, so they're not too bad.

 

[Alondro]

Are these relays? They look like they have a switch drawing on them

They sure look like relays.

One simple way to tell is the number of legs the little boxes have. Crappy rectangular foil capacitors only have two legs. Relays will have 3 or more. The smaller relays are more likely to have at least gold-plated contact points, because such tiny silver points could tarnish too much. HOWEVER, there are also some tiny silver-palladium alloy dots. And those tend to look very shiny, with a pale silvery hue.

 

[anarxi]

in the Soviet Union there were a lot of relays with solid gold contacts.
They can now be bought quite easily at online auctions.at the price of gold in their contacts.
This is due to the fact that gold has the least resistance.0.5 Ohm.
There are no pure platinum contacts,it is an alloy of platinum and iridium 90/10 in East Germany they used 70/30.
This alloy is extremely hard.but its resistance is already 1 ohm.

 

[anarxi]

Tomorrow I'm going to pick up various relays.
I bought them at an online auction.
there will be contacts made of gold-nickel alloy 95/5 and pli 10.
I'll take a photo.

 

[stella polaris]

Thank you @Alondro for showing that picture.
I have a box full of just such, saved them because they were very difficult to open and thought that they should lie until one day I know what they are and if they have something valuable in them.
Today is that day .
Thank you , Now the gloves are put on and the box is taken out again.
/Dennis

they are easy to opend. just squeese them with a kombination tool and they crack opend.

 

[stella polaris]

They sure look like relays.

One simple way to tell is the number of legs the little boxes have. Crappy rectangular foil capacitors only have two legs. Relays will have 3 or more. The smaller relays are more likely to have at least gold-plated contact points, because such tiny silver points could tarnish too much. HOWEVER, there are also some tiny silver-palladium alloy dots. And those tend to look very shiny, with a pale silvery

Alondo, it was in blue ones i found gold solder. Not much but it was there. Look and see if you find a 90 degree copper bend at the side of the relay. it is 2 parts soldered together.

And yes sometimes its very difficult to see the contact points. depends how the light is comming. I later discovered that some types i thrown away indeed had PM contacts.

 

[stella polaris]

Are these relays? They look like they have a switch drawing on them

They have a magnet spool that operates the switches.

 

[Proffshuggarn]

I later discovered that some types i thrown away indeed had PM contacts.

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