Worried about using an Modified Inverter

[DRAYCO]

Hi,

after reading alot of the past postings about inverters, it gave me worry about what i should get, i'm just basically starting out, i want to see if i can, not at the same time, run my computer and all its seconardy units, and at most run a 5amp A/C window unit. Ah, maybe a 300VA 5.1 surround sound system if i can

I read that noise, damage, all sorts of things can happen to your stuff, mainly stuff with high amount of electronics inside, TVs, computer, bla bla, when using a mod sine wave inverter

Well, what should i do ?

what is highly recommended for Pure Sine Wave? and what will run just fine on Modified Sine Wave?

example, lights (CFL), toaster, hot plate, heaters, battery chargers, router, modem, comp speakers, monitor, computer, standard 5.1 sys, high curren 5.1 sys, fan, A/C, anything really?

much thanks for any feed back

[drdongle]

If in doubt use pure sine, however.......... many of the devices you listed will work just fine on modified sine, the CFL lites, stereo, and possibility the battery charger MAY prefer pure sine wave, all the rest probably won't care. You could have two slightly smaller inverters one modified, one pure, there are several benefits, reduced expense, redundancy ( two are always better than one, in case one burns out), if the modified sine, burns out their cheaper to replace.

Carpe Vigor

Dr.D

[TomW]

DRAYCO;

I have run lots of stuff fine from mod sine inverters for over 2 years now. All my computer equipment [thats a wide range of stuff] 27" TV ceiling fans CF lites pretty much anything without a motor seems to be fine and many things with motors are ok. No inverter related failures to date.

Don't let the theoretical paranoids out there scare you off mod sine inverters. Many of us use them fine for almost everything. Admittedly motors do run a bit hotter and use more power than on pure sinewave power. Fact is anything electronic like a TV stereo or computer actually uses DC inside.

Anyway bottom line is if you are rich or paranoid then waste money on pure sine wave gear but otherwise you probably will be fine. I know from real world experience that they power most stuff just fine.

I know I addressed this in great detail before so a search may turn up the same diatribe elsewhere on the site. I only relate my actual real world experience but as usual your mileage may vary and no warranty expressed or implied. Use at your own risk, etc.

Cheers.

TomW

[kurt]

just don't plug your cordless drill battery pack charger into a mod sine inverter there the one thing that for sure looses there magic smoke when you try to run them off mod sine.

[TomW]

Yeah, Kurt is right. I kinda forgot that issue since it was way in the beginning when it happened to me.

Standard disclaimer applies to all my posts.

Cheers.

TomW

[hvirtane]

What is actually the reason, some appliances

like battery chargers are not happy with the modified sine wave? Can something be done for

the problem? Is it possible to 'smooth' the current

wave form somehow? With some capacitors, maybe?

- Hannu

[StanB]

Are computer UPS battery backups modified sine wave or full sine wave?? I have a shelf full of them I want to use.

Thanks

[stm]

This depends on the make and model - The APC smartups is a "true" sine inverter with a battery - check the manufactor's web-site - you will usualy find the information in the spec's.

/Steffen

BTW: somebody once taught me that modified sinewave is usuable for any resistive loads ie heating, standard lightning (not cfl!)

True sinus is required for any inductive load such as motors (some motors will run with a modified sine wave, but it is not efficient), anything with a transformer, and switchmode powersupply's

[Demetri]

CFL lights will run just fine on mod sine power. Mine seem to buzz just a little bit more than on pure sine when they are cold, and I've heard that some brands or older, more primitive, bulbs will die horribly in a matter of weeks. I've not had that problem, and light my entire house with them, 18 bulbs or so. My Harman/Kardon amplifier sounds clearer and more crisp on mod sine power than it did on grid power, but does get warmer. This computer I'm typing this on is powered by mod sine power, no problems. HTH.

Demetri

[12volt dan]

I've used a mod sine wave to charge my 12v drill with no problems. should I be worried?

[(unknown)]

As far as I know about AC electronics, which isn't that much as I am still studying, modified sine wave will not make a difference in normal traditional coil transformers. Modified sine wave goes in with it's plateaus and all & due to harmonics pure sine comes out. Great!

However, switchmode transformers do not do this harmonics business. So technically for such devices to work properly a pure sine source must be used. As is my understanding of this subject so far, correct me if you need to.

But aren't switchmode transformers used in computer power supplies & monitors just about everywhere? So really, exactly how crucial is a pure sine source for switchmode devices?

[hvirtane]

modified sine wave will not make a difference in normal traditional coil transformers. Modified sine wave goes in with it's plateaus and all & due to harmonics pure sine comes out. Great!

If one would put there a 1:1 transformer

after the inverter,

it would make of the modified sine wave

AC current quite like a sine AC current out?

- Hannu

[TomW]

Hannu;

modified sine wave will not make a difference in normal traditional coil transformers. Modified sine wave goes in with it's plateaus and all & due to harmonics pure sine comes out. Great!

Just to test this theory I grabbed a 12 volt AC wall wart which is simply a 10:1 stepdown transformer. With a square wave going in I get a square wave coming out with ever so slightly rounded corners on the waveform. Hardly enough difference to be worth any transformer losses and certainly no pure sine wave.

Just a 5 minute quickie test on one transformer and not a 1:1 setup which perhaps could alter things but I wouldn't bet on it.

Cheers.

TomW

[(unknown)]

I said modified square wave.

A normal square wave does not flatten out at zero for any period of time.

The first fundamental of a modified square wave is a sine wave. Or som,ething very similar. Grab a pencil & paper & draw it out to see.

If you draw a modified square wave and overlay a pure sine wave on top, you will see (assuming the drawing is more or less even/accurate) how the sudden changes in the modified sqaure waveform correspond to the sine waveform.

[TomW]

Tarzegaljaavan;

Well, excuse me! I neglected to say modified. I didn't count the steps but what you put in is what you get out. No corners or angle junctions in a true sine wave which is a smooth waveform.

Probably mostly semantics but a sinewave is fairly well understood to be devoid of steps and has smooth curves.

Just grab your trusty o-scope like I did and do some observation and you will see the reality here which is "You get out what you put in". If all it took to make a stepped wave into a sinewave was a transformer everyone would be adding transformers to their cheap inverters so they could toss out that pure sine wave designation and jack the price.

Theory and real world often clash and at that point you need to trust your observations. This I know from over 30 years in the field.

Good luck with your continuing education.

Cheers.

TomW

[(unknown)]

TomW,

Hey don't take me for being narky or jumping down your throat in any, the way I found this thread was through a Google search as I am not exactly sure about this subject.

What I posted was what was explained to me by one of my lecturers when I asked him about this modified square wave/sine wave business. After all, I am shopping for a UPS just like the 1st person in this thread.

So it seems like square one again. No pun.