Unknown Magnet Switches

[Claudie]

This is one of the boards I recently acquired in a lot of scrap from a very old time electronics hobbyist.
I have never seen these types of switches, or a board like this. The Copper coils each have three glass tubes running through them containing two flat metal rods with Gold plated ends. Is anyone here familiar with these? :|

 

[etack]

I believe they are reed switches.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=8695&p=88536&hilit=reed+switches#p88536

Eric 8)

 

[Geo]

yes, i have. let me round up a couple of different ones i have and ill post pics. the most troubling example is some that i have that are "mercury wetted" switches with an arrow and the word "up" at one end. i tore into one being careful not to break the glass and sure enough each has a ball of silver colored mercury about the size of a match head inside, but on these the entire length of the rod is gold plated.

 

[Claudie]

I believe they are reed switches.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=8695&p=88536&hilit=reed+switches#p88536

Eric 8)

I believe you are quite right! Thank you very much.

 

[Claudie]

yes, i have. let me round up a couple of different ones i have and ill post pics. the most troubling example is some that i have that are "mercury wetted" switches with an arrow and the word "up" at one end. i tore into one being careful not to break the glass and sure enough each has a ball of silver colored mercury about the size of a match head inside, but on these the entire length of the rod is gold plated.

The video I watched on the link from the previous post stated that they were usually filled with an inert gas like Nitrogen (some may argue that Nitrogen is really not an inert gas). If they contained Mercury, wouldn't that be a common Mercury switch and not a magnetic switch? The one I broke was broken by accident and the first thing I looked for was traces of Mercury. Thankfully, I didn't find any, I hate spilling Mercury of any kind.

Edit: Spelling

 

[qst42know]

Reed switches can contain mercury even if you don't see it.

Because of the close proximity of the leads in a reed switch a droplet wouldn't do, but a surface wetted with mercury does enhance the reliability of the switch. You may want to use caution when dealing with any reed switches. Or perhaps skip processing them all together.

http://en.wikipedia.org/wiki/Reed_switch

 

[notch]

Some reed switches also have Palladium contacts. It was pretty expensive technology at the time. These days, magnetic switches are solid-state Hall Effect devices.

 

[Claudie]

I don't think I will be processing any of these switches, other than the one I accidentally broke. I will save them for a collector or maybe try them on E-Bay someday. I have a special "box of junk" that I put stuff like this in. :|
Thank you all for the information. I am always learning something here!
Claudie

 

[Geo]

heres the mercury wetted switch. i have a few dozen of these.

 

[macfixer01]

yes, i have. let me round up a couple of different ones i have and ill post pics. the most troubling example is some that i have that are "mercury wetted" switches with an arrow and the word "up" at one end. i tore into one being careful not to break the glass and sure enough each has a ball of silver colored mercury about the size of a match head inside, but on these the entire length of the rod is gold plated.

The video I watched on the link from the previous post stated that they were usually filled with an inert gas like Nitrogen (some may argue that Nitrogen is really not an inert gas). If they contained Mercury, wouldn't that be a common Mercury switch and not a magnetic switch? The one I broke was broken by accident and the first thing I looked for was traces of Mercury. Thankfully, I didn't find any, I hate spilling Mercury of any kind.

Edit: Spelling

No a Mercury Switch is a different animal. In a Mercury (tilt) Switch, when the glass capsule is physically tilted beyond a certain point the mercury bead inside moves completing a connection between stationary contacts. In devices where mercury isn't acceptable (like toys) tilt switches use steel balls to make contact but they can get away with that since they're generally just low power battery powered devices and usually only need a momentary contact anyway.

Reed switches contain two springy flat ferromagnetic leads that bend into contact with each other when placed within a magnetic field. Basically by mounting the reed switch inside a coil they've just turned it into a relay. Mercury wetted contacts is another variant and can be used on relays and several other types of switches, not just reed switches. To me if the contacts are gold plated it makes no sense it would also contain any mercury since it would just amalgamate with the gold. In any case to be an effective set of mercury wetted contacts you'd really need enough of a mercury coating that you would be able to see it.

macfixer01

 

[Geo]

the mercury inside this switch can be shaken from one end to another. the close up shows the mercury at one end.

 

[Claudie]

I took one of these out of the Copper coil that it was ran through. I was successful in getting it out without breaking the glass. These don't have any visible Mercury in them. I did read the Wilki page about them, and it appears that some of them do in fact contain Mercury. Geo has some, and has posted pictures, so they must exist. The ones I have do have Gold plated ends.

 

[qst42know]

If gold in color a mercury content is not likely. Mercury is a potent whitener.

I have no yield info, but expect working in a sealed glass envelope would need precious little gold to function, perhaps even less than junk jewelery that requires enough for color. Of the ones I have seen the coating is very pale, just barely yellow at all.