Inverters & Laptops
 

"Hobbs" wrote in
:

Thankfully, we don't have WalMart in Australia at this time. (at least
as far as I know we don't)


No wonder prices are so high!

Larry
--
Have a little fun in the checkout line....
Ask the nearest American, "Did you see the ICE
agents chasing those Mexicans out the back door?"
....Shortens that checkout line right up...(c;

Inverters & Laptops
 

Larry wrote:
"Hobbs" wrote in
:

Thankfully, we don't have WalMart in Australia at this time. (at least
as far as I know we don't)


No wonder prices are so high!

Larry

And the wages!

--
Kees

Inverters & Laptops
 

I didn't say true sine wave, I said modified sine wave.
I can't remember the last time I saw a square wave inverter for
sale. With digital control, modified sine wave is ASMOP (A Simple
Matter Of Programming).

A square wave inverter goes to +120V (or whatever) for 1/120 second, then
to -120V (or ...) for 1/120 second.

A modified sine wave inverter goes to +120V for a bit less than 1/120 second,
then to zero for a bit, then to -120V for a bit less than 1/120 second,
then to zero for a bit. The net is that the area under the curve is the
same as a sine wave. (Note: the above assume 60Hz. at 50Hz it would
be 1/100 second).

West Marine (they ship international) has a 700W continuous, 1800W surge
modified sine wave inverter for US$69.99

As I said, no excuse for a square wave inverter these days.

"Shaun Van Poecke" wrote in message ...

"Chuck Tribolet" wrote in message ...
There's no excuse for using a square wave inverter these days. Modified sine wave inverters
are cheap.

sigh~ not everywhere in the world is as lucky as the USA ;-) here in australia we're still a bit backwards. small square wave
inverters at 150watts start at $AU50, while something as exoting as a 1000watt square wave costs about AU$400. a sine wave
1000watt inverter costs about AU$800.

Shaun

Inverters & Laptops
 

On Sat, 10 Mar 2007 08:14:11 -0800, "Chuck Tribolet"
wrote:

I didn't say true sine wave, I said modified sine wave.
I can't remember the last time I saw a square wave inverter for
sale. With digital control, modified sine wave is ASMOP (A Simple
Matter Of Programming).

A square wave inverter goes to +120V (or whatever) for 1/120 second, then
to -120V (or ...) for 1/120 second.

A modified sine wave inverter goes to +120V for a bit less than 1/120 second,
then to zero for a bit, then to -120V for a bit less than 1/120 second,
then to zero for a bit. The net is that the area under the curve is the
same as a sine wave. (Note: the above assume 60Hz. at 50Hz it would
be 1/100 second).

I must admit that I have always felt that the above should be called
"Modified square wave" as its resemblance to a pure sine wave is zero!
However that terminology would probably reduce sales.

--

Richard

Nb "Pound Eater" Parkend G+S
"Governments are like Nappies, they should be changed often."
(For the same reason)