Wind/Solar Electrics ???

On Mon, 19 Dec 2005 23:51:48 -0800, philkryder wrote:

Steve - How many equal "steps" are necessary for the MSW inverter to be
a sufficiently close approximation to a "rotary" sine wave?

It depends how you count "steps". I once worked with an inverter that
used two, count'em, two, output transformers, each driven by a plain
vanilla square wave, but they were in series, and the regulation
took place by controlling the phase of the two square waves - 120
times a second, the two secondaries flipped from "buck" to "boost".
The output waveform was essentially a positive pulse, then zero, then
a negative pulse, then zero, then another positive pulse, and so on.

It ran everything we plugged into it, even an induction motor bench
grinder. Lamps are trivial, and series motors, like a hand drill,
don't care.

We didn't plug a computer into it, however, or anything with an SMPS,
so I guess my recommendation would be to check the spec on what it
is you're plugging into it.

Good Luck!
Rich

"....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...

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...

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

On Wed, 21 Dec 2005 15:48:32 GMT, Rich Grise
wrote:

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?

(100/10)+1 = 11
I used to farm.


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

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

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

With risers it is the same confusion.

"Rich Grise" wrote in
message
news
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