Microwave oven safety switches, rough breakdown
You know the sort > http://i.ebayimg.com/t/Micro-Switch-...Rmw~~60_35.JPG
I had been putting these aside for a project & then decided I don't need a unmade project thats over 4 years old....
Since I have been scrapping switches & such for their silver content & found a few 'Gold bar' contacts in them, I decided to do a breakdown for ****z & giggles.
So, after pulling over 120 of these random switches apart (I get them from everywhere, not just microwave ovens.)
I found theres a average of >
58% 2 pole Silver &/or Silver-Copper contact face switches.
30% 3 pole Silver &/or Silver-Copper contact face switches.
9% ? pole Gold &/or Silver bar contact face switches
2% 3 pole Silver-Copper contact face switches of a completly different internal design. These have different outside cases, bakelite resin base with a white plastic clipon casing.
1% 'touch only' switches, they contact only when pushed & are contact faceless. ie just brass against brass.
Of the 9% switches with Gold or Silver bar contacts in them. There was 11 Gold bars & 17 Silver bars which were about 0.8mm x 0.8mm x 1.2mm long. Loaf of bread or trianglar shaped.
They look like this pic, with many thanks to oldtoothlessbassmaster who without we would never get to see the Gold bars here v
http://i1151.photobucket.com/albums/...psad3459ab.jpg
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Of the 3 pole switches, I found that 2/3rds of the total amount of contacts are solid Silver & 1/3rd are Copper with a Silver face welded onto it.
Of the 2 pole switches, I found that 1/3rd are solid Silver & 2/3rds are solid Copper with a Silver face welded onto it.
This seems to indicate that, on average, the centre pole is a double faced solid Silver contact in all of the switches & the outer poles (only one face) is Silver/Copper. Silver being the actual contact face.
The only real difference being that the 2 pole only has 2 contacts (two contact faces) &, well you guessed it, the 3 pole has 3 contacts (four contact faces)
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What was inside them, reflections & other guff.
1. Surprisingly there were no magnetic contacts at all.
2. It didn't matter who or how they were made, or if they were of a clip together design, or held together by a peined over aluminium pin. It whats inside seemed totally random.
ie, looking at the outside of the switch was no indication of whats inside it. Except for the two that were bakelite resin base with a white plastic clipon casing.
3. I expected to find a bunch of arced over & welded shut contacts, since thats what happens when you open the microwave door without stopping the microwave oven.
Thats the reason why most microwaves die, a $2 switch. Some switches were black with oxidation from arcing, I expect that the oxide stopped them from making a electrical contact.
Handy info for people who are about to scrap a microwave with Ali windings in the transformer. Don't scrap it, check if the switches work, replace them. Use or sell the microwave for $$
4. There was only one, in over 130 switches, where the contacts were arced so badly that the actual contact fell out
wow, hope this makes sense
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In a few days I will break the contacts down to get a weighted return of the solid Silver & the solid Copper with Silver faces contacts.
It may take a while to find out the weight of the Gold & Silver bars. My scales are not that accurate. @ 0.1gms.
It took me a hour to break the switches down & another 1 & 1/2 to post all of this, nearly lost it all too when the computer timed out.....
