Metal Plate

Just a metal plate. That's all that was found on the top of the doors. Held down with little nails. It worked for a long time. The plastic contact recessed in the jamb cleared when the doors were close. What heck was it and how did it work?

It finally failed. That's how I discovered this little oddity. I think I recall somebody on here mentioning something like it in the past.

Reply to
Bob La Londe
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Trying to read between the lines and come up with something that is plausible here is my guess.

Some very different contact that has a magnet built in so that when the metal plate was in position the magnet was attracted to in thus causing a set of contacts to be opened or closed inside the device.

Never heard of such a set up. Might work on a metal door, but doubt it. Would not ever install one even if it was free. Could be from a parallel universe that brushed too close.

Take pictures and post somewhere for all to see.


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Did you remove one of these metal plates? And was it in fact a metal plate, or was there a magnet under it?

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I've seen that before but there was a magnet under that plate, strange setup

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Which would magntize the plate and keep it working when the door warps and alignment is lost???

Just guessing... never seen it done.

- Chris

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ademco made one back in the 70's that had a complete switch/magnet in the jam and a metal plate on the moving part.. (no magnet under the metal plate..) the units could be used on a metal door without the metal plate.. the unit worked best if the switch/maget was placed in a wooden jam, cause if a metal jam the magnet would over time magnetize the jam and the switch would become questionable at best.... we used hundreds of them up till around 1981. RTS

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itch/magnet =EF=BF=BDin the

m =EF=BF=BDand the

I'm pretty sure it was the Ademco # 56 magnetic contact. Cloudy white plastic case with switch and magnet inside. Brassy colored plate came with two little nails so you could attach it to the edge of the door. I've got a couple down in the alarm dungeon. They were supposed to take the place of the #116 push button switches.

They were quite the innovation until they were out in the field for a few years. Then the sliding magnets inside the case started to hang-up after prolonged use or if they were used on a very busy door. As you said, they didn't do too well on metal doors either.

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Well it would seem that my absolute guess was spot on.

Oh goodie for me!!!!


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Ademco had some really strange contacts and switches back then but this was also the age when we foiled and you needed all the ornaments to make things work. the magnets worked on repulsion theory .

Reply to
nick markowitz

e switch/magnet =EF=BF=BDin

metal plate..

in a wooden jam,

e jam =EF=BF=BDand


Which contacts were those?

The # 56 used attraction to the metal plate. I don't remember any that used repulsion. Although there were some that were pretty repul ....sive!

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