Arfa Daily wrote:
"Andrew Gabriel" wrote in message
...
In article ,
Andy Champ writes:
Andrew Gabriel wrote:
In article ,
"The Medway Handyman" writes:
snip
It mentions in the spec "These inverters generate a modified sine wave,
which although not perfect, is considerably superior to the square
waves
which are produced by most other inverters".

Is that a good thing?
Yes, but it's also marketing bull****. I've never seen an
inverter which produces square waves -- they all produce
a modified sine wave. This one basically adds an extended
zero crossing period which is as crude as you can get without
being a square wave. Some more advanced ones have a stepped
sine wave.

All the ones I've ever looked at are made up from a bit of zero volts, a
bigger bit of plus volts, a bit of zero volts, then a bit of minus. If
you draw a graph with a very blunt pencil then take your glasses off and
put someone else on, then turn out the light you *might* think that's a
sine wave.
Yes, that's exactly what this one does.

Nevertheless mine seemed to drive my laptop (which was old enough for me
not to care about killing it) for a week on a canal boat.
Most computer PSU's don't care. Actually, many would run
better off a square wave.

On what do you base that ? A computer PSU is designed to run with a sine
wave input. It's like saying that my diesel car runs better if I put petrol
in it ...


No, it isn't.Its in fact as it happens designed to run off anything
witha peak volatge of between about 300 and 400V,since all the PSU does
to start with is rectify what it sees and smooth it - if that is mains,
thats about 430VDC. It could just as easily BE 430VDC.

In fact I worked on a project once where the same power supply could be
used on 48VDC, 120VAC, 230VAC with no reconfiguration required.

In short everything from 48-250V AC or DC was able to make it work.

It's treansformers that get hot under the collar with non sine mains.
But even then not that much.

Arfa