Anyone have any idea just "how modified" the waveform is on these
inexpensive inverters.
I have the "modified" inverter and a sine wave inverter, too.
"Modified sine wave" is a marketing term. The more accurate term, used
less frequently is "modified square wave". "Effective sine wave", while
not used, has meaning, and the "modified" type inverters have the same
peak to peak voltage and RMS voltage as the sine wave they are used to
replace. What they do *not* have is the same *spectrum*. They have
harmonics, while pure sine power has only the one spike in the
spectrum.
It helps to have both types and test all loads with each type to see if
the "modified" type induces unacceptable heating, or perhaps unsteady
operation in the connected device. Even a sine wave inverter will not
drive the most sensitive loads. But they will drive almost any load.
It makes sense to drive small loads, when possible with a modified type
inverter, as they are substantially more efficient with small loads.
Larger loads that can use either inverter are best driven with the
least expennsive inverter. My inverters are rated in idle current and
full load current. The pure sine wave inverter draws about four times
the idle current that the modified type draws. At the same larger load,
their consumption is almost the same, but you already mentioned the
price....
A true sine wave inverter would be like a class C amplifier, or even
class A. Very ineffienct, but high quality power. It's said this has
been done with high power car audio amps. I cannot confirm it.
I am experimenting with self-excited induction generators, a heavy,
medium efficiency source of extremely pure sine wave power, when
adapted to a particular load. Search "SEIG" for these
mechanical-to-electrical "converters".
Yours,
Doug Goncz
Replikon Research
Falls Church, VA 22044-0394
DGoncz at aol dot com email