Clare described them well. This is 2 styles opened up. The toggle cams the strap with the contact down against a pretty stiff spring to pop it open when you turn it off.
Yes. The silent switch action is relatively slow and there will be multiple zero crossings. Slow action is why the DC rating, if any, is far lower than the AC rating, as Clare said.
But not necessarily a "knife" switch
AC contactors may have multiple horseshoe shaped iron pieces around where the arc will be (arc chute). The arc current creates a magnetic field in the pieces that lengthens the arc - blow out.
Haven't seen DC contactors, but I suspect the construction is similar.
From the UL White Book "SNAP SWITCHES (WJQR) AC GENERAL-USE SNAP SWITCHES [probably includes all the silent switches] AC general-use snap switches are tested for the control of resistive, inductive (including electric discharge lamp) and tungsten-filament lamp loads at 120 V up to the full current rating of the switch, and for motor loads up to 80% of the amp rating of the switch, but not exceeding
2 hp."Any garden variety AC-only wall switch should have the HP rating.
UL testing (1991 version) included:
10,000 operations with an incandescent light load [inrush greater than rated current] Also testing similar to closing on locked rotor current for a motor at 80% of amp rating. And quite limited number of tests for opening on locked rotor current for a motor at 80% of amp rating. A motor was not used, but an equivalent load including inductance.
I vaguely remember debounce circuits being required in some designs (in the equipment, not the switch) because most switches have at least some multiple events, and if timing is critical it has to be prepared for.
I can't remember an example though.
You are typing on one.
Around 1960, there were as many silent switches as people chose to buy.
We might have bought one or two except we didn't have any broken switchers to replace, the noise of the current switches weren't bothering anyone, and the silent ones were more expensive.
So what. 99+% off all these 110v toggle switches are mounted that way anyhow. I think I put one in my model train platform that was horizontal but's the only one I can think of.
The silent swtiches I refer to had no detent.
Back in the 40s and 50s rich people did have mercury switches that were completely silent and smooth operating because it was just a tube of mercury with a couple of contacts in it. They were several bucks each at a time when Porterhouse steak was 59 cents a pound. These days a silent switch is just a pair of contact points cammed together by the toggle handle.
I meant to say there may have been a very few "early" silent switches that used mercury - but very few
Without a "detent" they would not stay in the position you put them in unless they used a "friction break" - but without a detent they could sit half way between on and off, arcing (in the mercury bulb?) causing the switch to fail quickly. Virtually ALL switches have a "detent" of some sort.
And I'll correct myself here before Micky or someone else does - not ALL were "knife" switched - some were not a wiped contact but they WERE over-center "snap" switches that DID open and close extremely quickly compared to a "silent"switch
I can't remember the last time I argued with you. ;-)
Back in the early 80's I moved into an apartment with the loud snap switches. I bought a bunch of silent switches and replaced them all, putting the loud ones in a closet.
2 years later I bought a house with the loud snap switches. Before I moved out of the apartment, I swapped the loud ones back in and used the quiet ones in the house.Part of me said "They are mine, I'm taking them with me" and part of me said "I don't want them knowing that I was messing with wiring." I doubt the "upgrade" would have impacted my security deposit, but why take the chance?
When I moved in here, the shower head was surely the original one, but I thought it didn't have enough water. Somehow I already had a nicer one and I put it on. I'm planning to change back before I leave so I can use the good one at the nursing home I end up in.
Some landlords would complain, I think, and you don't know in advance which ones. I think on the People's Court I've seen landlords complain about what anyone would call an improvement.
When I lived in NY, the bathtub drain was outside the tub, a separate pipe in a pipe as high as the water level in the tub was allowed to be. When you lift the plunger, the inner pipe, the water drains right at floor level. I taped up the overflow holes in the top of the plunger (which were much bigger than the ones in the video) so I could fill the tub another 2 inches, and then I could float with only 2 or 3 square inches of my rear end touching the bottom. I was afraid I would forget to untape it when I left but I didn't forget.
Mine was prettier, brass with a white ceramic knob on top. I didn't know what it was when I first moved in.
Here in Baltimore, I took the overflow for the tub and turned it upside down. I think this gives me one inch more depth. This change is obvious from the outside and the tub needs remodeling anyhow, and these overflows seem insufficient anyhow, but I do plan to put it back the way it ws.
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