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.

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

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

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

"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

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

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

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

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

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