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#71
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Wind/Solar Electrics ???
George Ghio wrote:
Tell us why anyone would modify a sine wave. It's called "engineering," George. Nick |
#72
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Wind/Solar Electrics ???
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. Matt |
#73
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Wind/Solar Electrics ???
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#74
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Wind/Solar Electrics ???
On Tue, 20 Dec 2005 23:00:43 -0800, philkryder wrote:
"....It depends how you count "steps"." Indeed. I suppose something like "the number of distinct voltage changes per cycle" might be a good first approximation of something to call steps and to count. In your example I would count something like "3" or maybe "2" or "4" - I always have trouble with boundary conditions... Heh. Programmers run into this all of the time - it's called "the fencepost effect". If you have a 100' fence, and there's a post every 10', how many posts do you need? Or this one: Imagine a short staircase, say to a "sunken living room" or some such, of 3 steps: ------------ | ----- | ----- | --------------------------- Now, if you had three apples, you'd be able to count them, 1, 2, 3, and point at the middle one. OK, now go up those three steps, counting along, and point at the middle one. Then go down, counting again, and _now_ point at the middle one. Isn't that cute? ;-) In any case, it seems that the device you had was effective. And the only thing I could imagine as having fewer steps would be a similar device that didn't have the pause at zero... And yet it was effective - I wonder if it would have worked with the light dimmer mentioned above... I think very probably not very well, if at all, based on what others have said. But, if you're on an inverter already, I think there'd be a more efficient kind of light dimmer that you could find, maybe that runs off the battery voltage. Or sync up your triac or SCR dimmer to the inverter itself - hmmmm.... (this one had a sync in/out so that they could be paralleled.) Thanks! Rich |
#75
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Wind/Solar Electrics ???
On Tue, 20 Dec 2005 23:35:15 -0800, meow2222 wrote:
Steve Spence wrote: philkryder wrote: Steve - How many equal "steps" are necessary for the MSW inverter to be a sufficiently close approximation to a "rotary" sine wave? That depends on what you are driving. A laser printer requires closer representation than a computer. The manufacturer of a particular load could tell you that information. The old test of whether something was sine or some version of square was a lamp dimmer. On a square wave unit the light goes full bright. We have a touch lamp that will not change state on MSW, but will on generator. A lot of ac loads are quite happy on dc. Almost anything that rectifies the mains waveform will run fine on dc of V_mains x 1.414. NT Well, don't plug a 120VAC wall wart into 170VDC! Or should we alert the Darwin committee? ;-) Thanks! Rich |
#76
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Wind/Solar Electrics ???
wrote....
"A lot of ac loads are quite happy on dc. Almost anything that rectifies the mains waveform will run fine on dc of V_mains x 1.414. " ....unless there is a transformer at the input to the power supply. Only thing that'll happen then is the transformer might get hot. Randy |
#77
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Wind/Solar Electrics ???
philkryder wrote:
"....We have a touch lamp that will not change state on MSW, but will on generator" Do you know if these new smaller Inverter style generators are a close enough approximation for things like the laser printer? Just how good are the "sine" like waves on them? I thought someone was going to put a 'scope on one... I don't have one (inverter/generator) to test. If it's a SW then yes, it will work. The HONDA EM50is claims to be a sine wave unit. -- Steve Spence Dir., Green Trust, http://www.green-trust.org Contributing Editor, http://www.off-grid.net http://www.rebelwolf.com/essn.html |
#79
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wrote:
George Ghio wrote: Tell us why anyone would modify a sine wave. It's called "engineering," George. Nick Really... Wouldn't they rather modify a square wave to approximate a sine wave? What would be the point of modifying a sine wave, when a sine wave (or close approximation) is the required result? -- Steve Spence Dir., Green Trust, http://www.green-trust.org Contributing Editor, http://www.off-grid.net http://www.rebelwolf.com/essn.html |
#80
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Wind/Solar Electrics ???
On Wed, 21 Dec 2005 14:06:05 -0500, Steve Spence wrote:
philkryder wrote: "....We have a touch lamp that will not change state on MSW, but will on generator" Do you know if these new smaller Inverter style generators are a close enough approximation for things like the laser printer? Just how good are the "sine" like waves on them? I thought someone was going to put a 'scope on one... I don't have one (inverter/generator) to test. If it's a SW then yes, it will work. The HONDA EM50is claims to be a sine wave unit. It seems pretty obvious that a mechanical generator should put out a relatively pure sine wave - it's just this big rotating magnetic field and a couple of coils, after all. :-) As a matter of fact, it's a little hard for me to visualize how someone would make anything _other than_ a plain vanilla sine wave using just a rotating magnet and a coil. Thanks! Rich |
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