Whole house "battery" wiring/power...


James Sweet wrote:

The foreign 50hz stuff I've seen is a lot more massive than my home grown 60hz equipment. I've worked on all sorts of switching power supplies but I've never seen a 1Mhz unit. Is it something that would be an aerospace/military item?
TDD
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Thats why Westinghouse beat Edison in the early days of deciding what electical distribution system to use, Westinghouse (scientist) wanted AC, Edison (who was more of an inventor than a scientist) would not let go of his prejudice for DC. I still have an old AC/DC radio from those days, when radios were sold to work on either distribution system.
Westinghouse was an inventor, and entrepreneur (as was Edison) - who recognized good ideas when he saw them and a way to get around Edison's stranglehold on the electrical "lighting" systems. This was weakened before Tesla, by Gaulard and Gibbs who invented the transformer (1886 or thereabouts for the first AC transmission). - making long distance transmission possible. polyphase machines invented by Tesla were the icing on the cake, and 3 phase systems followed soon after. Edison wanted to hang onto his empire- so fought tooth and nail against AC- he had a good thing going. Tesla once worked for him but got shafted. As for the radio- If I recall correctly, until the late 1920's all radios were battery powered. Then AC/DC units came into use. Better ones used transformers to get the various voltages, filament and plate (replacing the old A and B batteries). The typical smaller radios that were sold in the 40's and 50's would work on DC as they did not have a transformer, and tubes operated on the rectified line voltage, with tube filaments in series. This was done, not with intent to use them on DC supplies but because they were considerably cheaper to build but could have a hot chassis (safety? what's that?).
The history of those times is very interesting. An often ignored inventor who thought things out before trying them (as opposed to the Edison approach) , was Elihu Thompson.
--
Don Kelly
snipped-for-privacy@shawcross.ca
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Don Kelly wrote:

When I was a kid, I got hold of an old tube type record player that had a metal chassis, for some reason when I was playing around with it on the back porch of our house, I got lit up.     DANG!! This was long before two wire cords had a wide bladed neutral. With all the electrical devices I played with when I was a kid, I'm surprised I ever survived.
TDD
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--
Hey, you\'ve got an old radio which has seen better days- maybe even missing
its case but still working - put it in the shop or better yet in the laundry
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On Fri, 09 Oct 2009 18:49:52 -0500, The Daring Dufas

Somehow my hand ended up between the poles of a 10kV Jacob's ladder on day, while sitting indian style in front of it.
It shot me back about seven feet (my legs). I am sure I clamped the supply down to near nothing, since it was only a 10mA furnace ignition transformer.
That one was phase independent. Surprised I survived my youth as well. I made a shock box "lie detector" as a science project, and was shocking parents with it... mostly. Back then, a kid could get away with that stuff.
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Archimedes' Lever wrote:

I've been told that when I was an infant crawling around the house back in the middle of the last century, I unplugged the power cord from the bottom of my mother's Singer sewing machine. The other end of the cord was still plugged into the wall outlet and being the curious little brat that I was, decided to determine what a power cord tasted like. I've been told that I turned blue and my diaper had to be changed. Ever since then I've been getting in trouble for things I've done with electricity. When I was a bit older, I would build Frankenstein like machines in the basement and being no fool, I would get one of my little brothers to plug it in while I took cover behind something. It made my butt hurt for some reason.
TDD
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On Sat, 10 Oct 2009 13:49:27 -0500, The Daring Dufas

That's your ass on fire because you are going to hell. :-]
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AC/DC radios were born out of the great depression. It was the Volkswagen Beetle of radios. The reason for the design was that it eliminated the (expensive) power transformer by wiring all the tube heaters in series and made the set much cheaper to manufacture. A useful side effect of this was that it would work on either AC or DC. An additional potentially very dangerous side effect is that depending on which way the plug was inserted into the receptacle, the entire metal chassis could be live, including shafts that would be exposed by a missing knob.
The classic "All American Five" so named for the lineup of five tubes used in virtually all of them was prolific up into at least the mid 60s. It really is remarkable just how well it worked, despite circuit layout and wiring techniques that would make an RF engineer cringe. It is highly advisable to power these from an isolation transformer.
Incidentally, I read a few years back that it wasn't until the late 1990s that the last DC service was disconnected from a building, somewhere in NY I think. I was amazed by how long it remained in use.
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James Sweet wrote:

(snip)
Servicing some legacy elevator motors or building water pumps, IIRC. Wikipedia has a pretty good writeup, linked from the 'current wars' articles. Isn't their subway system still DC? I would never want to live in NYC (or any huge city), but I do find the historical stuff about their physical infrastructure quite fascinating. The occasional show on History, Discovery, or similar channels always sets me off on an internet hunt. If I could get shows like that on over-the-air TV (like PBS in the old days), I'd probably get rid of my satt service.
-- aem sends...
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On Fri, 9 Oct 2009 09:04:47 -0700 (PDT), windcrest

^^^^^^^^^^^^^^^^ Idiot. It is prejudice AGAINST AC.
It is a derogatory term, so there is no prejudice FOR anything.
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On Sat, 10 Oct 2009 10:27:26 -0700, Archimedes' Lever

AlwaysWrong strikes again.
http://www.merriam-webster.com/dictionary/prejudice
Definition 2a: preconceived judgment or opinion
It has a negative connotation because it is preconceived, not because what is preconceived is negative (or even AC).
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A prejudice is usually something one has against something, not for it.
To be for something is to be "partial to" or "predispositioned for" something.
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On Sat, 10 Oct 2009 15:54:42 -0700, Archimedes' Lever

"Usually" has nothing to do with it, DimBulb. The word was used correctly. You were wrong again, AlwaysWrong.

Synonyms, noting more or less.
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On Sun, 04 Oct 2009 22:11:23 -0500, The Daring Dufas wrote:

Around 2002 I found a wonderful mid-sized mercury arc recifier in use still for the tram system at the MOTAT museum in Auckland, NZ - it might still be operational there. Fascinating to watch it run, and the brightness change according to load as the trams moved around.
I'm sure there are still some running in other countries, too, but that's the only one I've seen over the years (although various museums have ones that aren't hooked up - I don't know how many of those are still technically OK and could be made to run).
There may still be a few tucked away in buildings with really old DC elevators, although there can't be many left now that haven't been updated.
cheers
Jules
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On Wed, 07 Oct 2009 08:11:30 -0500, Jules

I do not think there have been DC elevators in the US since the late Thirties.
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On Wed, 07 Oct 2009 16:20:38 -0700, Archimedes' Lever

AlwaysWrong strikes again.
http://science.slashdot.org/article.pl?sid /11/16/225213 http://cityroom.blogs.nytimes.com/2007/11/14/off-goes-the-power-current-started-by-thomas-edison /
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"Still in use", and "Still being manufactured" are two different things, dipshit. Show me a modern nameplate date. Case closed.
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On Sat, 10 Oct 2009 13:02:34 -0700, Archimedes' Lever

Existed = have been. You said nothing about being manufactured, DimBulb. You implied that they didn't exist.
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Good thing that you are the only one that used the word. I never said anything about "existed". Though it is a shame that you do.
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On Sat, 10 Oct 2009 15:56:02 -0700, Archimedes' Lever

You really are a dim bulb, DimBulb. You said: "I do not think there have been DC elevators in the US since the late Thirties". The fact is that there _have_been_ (i.e. existed) DC elevators as recently as 2007. In fact they are likely still there, though the conversion would now be done on-premises.
In short, AlwaysWrong, you're wrong again.
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