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#101
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Wind/Solar Electrics ???
Finally, an excellent example of the purpose of a kill file...
-----Original Message----- From: ] Posted At: Thursday, December 22, 2005 10:59 AM Posted To: rec.aviation.owning Conversation: Wind/Solar Electrics ??? Subject: Wind/Solar Electrics ??? Why don't you ask this in the wind/solar electric NG you dumbass MoFo. |
#102
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Wind/Solar Electrics ???
Well, it ain't a perfect sinewave..it's a modified one.
"Rich Grise" wrote in message news On Thu, 22 Dec 2005 10:22:48 -0500, Steve Spence wrote: SolarFlare wrote: When a scope is put on the waveform the shape is a "modified sine wave" This is not a hard concept. Actually it's not a modified sine wave, it's still a square wave with many fine steps. Again, it's a marketing term, not a technical one. You don't "modify" the sine wave, you modify the square wave to approximate a sine wave. I like that one, but "approximated sine wave" just doesn't have the same marketing ring to it. :-) Cheers! Rich |
#103
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Wind/Solar Electrics ???
We still use saturable reactor based battery chargers
with a solid state feedback system for voltage and current regulation. Still the latest and greatest, most reliable technology we have in chargers. Not completely mag amps but same idea. Our mag amps use all went out years ago. I don't remember ever having to recal them. Wow! takes me back a ways...LOL "daestrom" wrote in message ... "Roger" wrote in message ... On Wed, 21 Dec 2005 14:29:00 GMT, Matt Whiting wrote: George Ghio wrote: Tell us why anyone would modify a sine wave. To vary the power delivered to a load. Chopping off part of a sine wave cycle is a standard means of power control. That makes three phase SCR (Silicon controlled rectifiers and not saturable core reactors) interesting as chopping off part of the wave form develops spikes and harmonics that tend to make the control of one phase interact with the others. I've built a lot of them for single phase control, but I never once was able to build one for three phase that didn't interact. Turn one up and maybe another would go up, Turn the second down and the other two might go up or down. Twas interesting:-)) which is probably why Saturable core reactors are so popular in industry. Now there is a controller that is a tad on the weighty side. Also, some old systems used self-saturating reactors (magnetic amplifiers, 'magamps') for instrumentation. Things could take some severe environments, but calibration tended to drift a lot. Required fairly frequent 'trip & cals' to keep them in spec. daestrom |
#104
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Wind/Solar Electrics ???
Three risers though.
"Roger" wrote in message ... Or this one: Imagine a short staircase, say to a "sunken living room" or some such, of 3 steps: ------------ | ----- | ----- | --------------------------- There are only two steps. on the stairway. The others are landings Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com |
#105
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Wind/Solar Electrics ???
"MSW is a shysters sales pitch which misrepresents the product. "
Are there deterministic tests that tell when a device has a "good enough" sine wave? Or is there some sort of accepted "spec"? I saw in another post where one of the EU2000 hondas had a beautiful "looking" wave form, but failed to run a furnace. What can we use to "know for sure" that the wave form of a device is adequate BEFORE buying it? Thanks Phil |
#106
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Wind/Solar Electrics ???
On Thu, 22 Dec 2005 22:01:02 -0500, SolarFlare top-posted:
Three risers though. Yabbut, that misses the point of the gag. It's easy to point at the three risers: .. ------------ .. | -- 1 , ----- .. | --2 .. ----- .. | -- 3 .. ------------- And, obviously, the middle one is #2. But, while stepping up or down the stairs, the way most people count steps, if you're going down, (to the right) you'd go: .. ------------ .. | 1 , ----- .. | 2 .. ----- .. | 3 .. ------------- And count 3 steps. But if you're going up, which is right-to-left in this exsample, you'd go: 3 .. ------------ .. | 2 , ----- .. | 1 .. ----- .. | .. ------------- because where you started from is zero in either case, but step 2 is different if you're going up or down. Hope This Hemps!^H^H^H^Hlps! %-} Rich "Roger" wrote in message ... Or this one: Imagine a short staircase, say to a "sunken living room" or some such, of 3 steps: ------------ | ----- | ----- | --------------------------- There are only two steps. on the stairway. The others are landings Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com |
#107
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Wind/Solar Electrics ???
Joel Kolstad wrote:
(I can't tell you how many times I've seen people stating something like, 'The Nyquist theorem requires sampling at at least twice the highest frequency present in the signal," when of course it says no such thing.) What do you think it means? Nick |
#108
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Wind/Solar Electrics ???
philkryder wrote:
Are there deterministic tests that tell when a device has a "good enough" sine wave? Or is there some sort of accepted "spec"? I've seen a 5% total harmonic distortion spec. How many steps is that? What can we use to "know for sure" that the wave form of a device is adequate BEFORE buying it? Try it out? I got a local dealer to start up an EU2000 and run it with and without a muffler. Nick |
#109
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Wind/Solar Electrics ???
On 22 Dec 2005 19:49:37 -0800, "philkryder" wrote: What can we use to "know for sure" that the wave form of a device is adequate BEFORE buying it? I've purchased a couple of ~$1500 machines from a local welding supplier on condition that if there were any problems running them off my SW inverters then the machines could be returned in as-new condition the following day and I'd buy a different model instead. That flexibility, and being able to see the machines in person, made the extra cost of buying locally worthwhile. Wayne |
#110
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Wind/Solar Electrics ???
wrote in message
... Joel Kolstad wrote: (I can't tell you how many times I've seen people stating something like, 'The Nyquist theorem requires sampling at at least twice the highest frequency present in the signal," when of course it says no such thing.) What do you think it means? It means that perfect reconstruction of a signal requires sampling at at least twice the _bandwidth_ of the signal present to insure that no aliasing occurs. Two important points he 1) It's the bandwidth of the signal that matters, not the highest frequency present (this is kind of the analog version of the digitial guys' "it's the edge rate that matters, not the clock speed"). This fact is frequently used to great advantage in radio receivers (and plenty of other designs, I'm sure). 2) The assumption that aliasing is inherently detrimental is not always true. I've seen designs where well-defined bandpass filters were stuck in front of an ADC and the aliasing was used _to advantage_ to let the ADC sample at much closer to 2x then one could have obtained with more traditional filter design. (Although I'd admit that this seems to have been more common when ADCs were slower and you had to use all the tricks you could to get performance out of them.) ---Joel |
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