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old hand
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old hand
Joined: Nov 2000
Posts: 819 |
When you go bra shopping, boxes labelled underwire in English are labelled armature in French. This causes my mother and me no end of giggles! It sure feels like "armature" is a better word for it sometimes!But what about the word, "brassiere" itself? You've got the word "bras" in it, so you've already got the "arm"-ature implied, n'est-ce- pas? Of course, we men would prefer that they had les mains avec les bras, but that's not an uplifting subject, now, is it? 
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Joined: Nov 2000
Posts: 819
old hand
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old hand
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Posts: 819 |
As regards alternatiors vs. generators, an alternator IS a generator, but it produces alternating current which is rectified to half-wave alternating current which can be used to charge a storage battery. The armature and field parts are reversed from their positions in an old-fashioned direct current generator, which also produces alternating current, but is internally rectified by the commutator. Since the heavy current is not carried by the commmutator and brushes, electrical and mechanical losses are far lower in the alternator type of dynamo.
For an alternative usage, read Alexis de Toqueville's description of the United States, wherein he describes the entire country as a dynamo.
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Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
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Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
" half-wave alternating current"
Dear Geoff: Forgive my saying it, but you will confuse readers with that phrase. When the negative wave has been blocked, you have a pulsating direct current.
I still remember how horrid it could be to have a battery a couple years old suddenly quit in stop-and-go heavy commuter traffic because old generator could not charge battery under those conditions.
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Joined: Oct 2000
Posts: 5,400
Carpal Tunnel
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Carpal Tunnel
Joined: Oct 2000
Posts: 5,400 |
RE:When the negative wave has been blocked, you have a pulsating direct current.
Yes, but nowday, with the use of rectifiers and diodes, it a rather simple operation to convert a pulsating direct current into a rather stable direct current.
zener diodes are used to limit the upper portion off the wave, and (okay, so i don't remember all my physics!) something else controls the lower half of the wave form.
the same sort of thing is used all the time in analog to digitital conversion.. the analog signal is converted into a pulsating direct current, which is further refined into digital pulses--frequentcy modulation, -- with all sort of circutry built in to comp for dopler effects.
(a long ago standard for hard drives was Modified Frequency Modulation.. MFM, aka mother f****** magic), details from the dredges of my mind..
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Joined: Aug 2001
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Carpal Tunnel
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Carpal Tunnel
Joined: Aug 2001
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Keiva spoke of early advocacy of a generator in every home. Terrible idea, inefficient, massive pollution, even dangerous. Great for boondocks and third world, but suggesting it in big cities is insane. uh, dr. bill, are you adjudging past positions as "terrible" based on the technology of the present?
In those days (before Insul/GE's breakthrough with the turbine generator, in roughly 1905) one simply could not build a generator big enough to produce enough power to serve a large area. So long as that was the case, any power sources would have to be diffused -- as indeed they had been throughout history. Given that, the advocacy of localized power-plants made a good deal of sense. Consider which would you prefer: for each building or small group of buildings to have:
(1) its own coal-fired generator, producing electrical power to be distributed by wire through the building; or
(2) its own coal-fired generator, producing mechanical power (a turning driveshaft), to be distributed by a series of belts and gears (more power-loss, by friction; plus danger of mechanical injury to person from whirring driveas and belt); or
(3) no power source other than muscle power -- human or animal -- with which to produce?
Post-edit: words in red above were added, as clarification, reflecting dr. bill's point below.
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Carpal Tunnel
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Carpal Tunnel
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the recent events in NY show the problem with centralized systems.. there is no direct power in over 1 square mile of NYC, since a substation was destroyed.. only facilities with back up generators didn't lose/have power. (there are giant "extention cords" all over the place bringing power into the area)
Telephone service (centralized sytem) has still not been restored to many, many places, both in and out of the no go zone. but the internet (a distributed system!) never went down.. i was unable to call my son, my phone had a dial tone, but i couldn't make anything but local calls. but 6PM on the 11th, i was able to get on line..
one of the underling causes of the conflict in mid east, is our (USA!) dependence on oil. maybe we should be using a distributed system, for power, and locally harnessing available resources. for me, there is almost a 10 year payback for a wind generating system, (and yes, i think my house, on top of hill gets enough of a breeze to power a wind generator) but if oil/natural gas where more expensive, my payback time might be shorter, and i might make the investment. I have too many trees on the south side, and live too far north to think of solar panels as an alternate energy source. but electricty has gotten expensive enough in CA to make them viable. in many sub urban areas, there are old, unused wells these could be used for geothermal energy conversion.
our centralize, power distributions monopolys have often pressured for laws to discourage distributed systems. maybe its time we rethought this. we have great infrastructure in US.. but like our old smokestack industries, maybe our investment in this technology is now becoming a hindrence.
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Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
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Carpal Tunnel
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1
" In those days one simply could not build a generator big enough to produce enough power
to serve a large area"
Dear Keiva: But Insull did it, and has never been adequately honored.
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Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
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Carpal Tunnel
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I goofed when I said Tesla was a Hungarian. He was a Croat. Here is URL containing 25K biographies.
http://search.biography.com/cgi-bin/frameit.cgi?p=http://search.biography.com/print_record.pl?id=11301 It is too long . Try edit,copy,,edit,paste You have to do a bit of navigating to find Tesla.
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Joined: Apr 2000
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Carpal Tunnel
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Carpal Tunnel
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In reply to:
Of course, we men would prefer that they had les mains avec les bras
Well, there's always the Venus de Milo....
Bingley
Bingley
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Carpal Tunnel
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Dear Keiva: But Insull did it, and has never been adequately honored.Okay, Bill, I take your point. "More power to him then". There, will that do? 
The idiot also known as Capfka ...
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