Inverter question: What is the difference between "modified" or

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rays

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Inverter question: What is the difference between \"modified\" or

"quasi" sine wave and "pure sinewave". The inverters producing "pure" are bloody expensive. Do I need to bother to run my laptop? Also, Maplins are selling a 600watt inverter for £39.99. This beats the chandlery price by 50%. I am tempted! Should I be? Help required!!

Cd
 
Re: Inverter question: What is the difference between \"modified\" or

I think you should be fine with a "quasi" sinewave inverter for your laptop. I think one of these would be fine for most equipment, although some AV-type equipment might be prone to interferance from this kind of inverter. The output from a sinewave inverter is "cleaner", but at the expence of more complex circuit (hence more expensive) and lower efficiency (reduced battery life).

So, use the cheap inverter if it's just a laptop, fridge or toaster, but if you wnt to run TV, radio or hi-fi then sinewave would be better.
 
Re: Inverter question: What is the difference between \"modified\" or

It depends on the laptop. Some (switched mode) power supplies rely heavily on chopping the sine wave accurately to operate. A quasi sine wave confuses them. You can try it, but check the price of a new laptop PSU.

Anything with a transformer in it should be fine. The hysteresis(sp?) of the core of the transformer will sort out the quasi sine wave and you will get a pretty good sine wave out of the other side.

I have tried to give a simple answer to a question that hasn't got an easy and obvious answer.
 
Re: Inverter question: What is the difference between \"modified\" or

A transformer output will have a wave form very simular to what goes in. Thats what I was taught during 43 years of experience in the power industry.

Yes, borrow a non -sine wave inverter and try it, should be ok,run mine`s a a cheapy seems to like it with no interference and is not to harsh on battery consumtion either,use a hand lead light (40 Watt) for evenings and its good for the shaver as well.
 
Re: Inverter question: What is the difference between \"modified\" or

I was lucky enough to buy a 500watt isolation transformer ie 230 to 230voltsfor £15 from a govt. surplus store previous to this I got a horizontal moving line on TV when using a video recorder.The prob. is I think that most modern electronics dont have transformers anymore to get lower voltages.When they did the transformers used to help sort out the sine wave.
 
Re: Inverter question: What is the difference between \"modified\" or

[ QUOTE ]
So, use the cheap inverter if it's just a laptop, fridge or toaster, but if you wnt to run TV, radio or hi-fi then sinewave would be better.

[/ QUOTE ]

I run a Philips 20 inch flat screen off a cheap 350W converter from Maplins - works fine. My DVD player also worked fine
 
Re: Inverter question: What is the difference between \"modified\" or

happily charging the laptop, the phone, the pda and my wife's ipod using a 14.99 inverter from aldi. they're back in by the way.
 
Re: Inverter question: What is the difference between \"modified\" or

[ QUOTE ]
[ QUOTE ]
So, use the cheap inverter if it's just a laptop, fridge or toaster, but if you wnt to run TV, radio or hi-fi then sinewave would be better.

[/ QUOTE ]

I run a Philips 20 inch flat screen off a cheap 350W converter from Maplins - works fine. My DVD player also worked fine

[/ QUOTE ]
To be honest, I didn't think it would be a problem in practise. I was struggling to think why anyone would want to pay extra for a sinewave inverter!
 
Re: Inverter question: What is the difference between \"modified\" or

Ray, we have an elderly Mastervolt inverter on the boat, which runs our TV, DVD Lap-Top, loo fridge etc. no problem.

I also bought the ‘cheapie’ from Maplins which I used to run the same Lap-Top in the car and I’ve run our Video recorder and a studio Colour monitor off it (powered by a battery charger – just to see if it worked) with no issues.

The only thing I have found that doesn’t work off an inverter is the UV/High Voltage mosquito/fly ‘zapper’ which dies in one night, when the tube blackens at both ends and never starts again!
 
Re: Inverter question: What is the difference between \"modified\" or

[ QUOTE ]
A transformer output will have a wave form very simular to what goes in. Thats what I was taught during 43 years of experience in the power industry.

[/ QUOTE ] Interesting idea and I am not sure that I agree with you. Try putting a square wave into a transformer and seeing how square the wave is coming out?

Actually, I was assuming that the quasi sine wave was a 'stepped sine wave' ie slightly more sophisticated than a square wave and approximating to the sine wave curve. How the transformer will affect this wave shape depends on a lot of factors including the nature of the load on the other side of the transformer, but I still think you will find that the hysteresis of the core of the transformer will tend to smooth the waveform. Furthermore, transformer-rectifier power supplies will certainly work with such a waveform, whilst some switch-mode power supplies won't - the answer required by the original post.
 
Re: Inverter question: What is the difference between \"modified\" or

It's very risky to use anything but pure sine wave on anything electronic - even my electric toothbrush chargers blow on modified sine! Some bit of kit are fine and there will not be a problem but others might either not work, or worse, overheat internally and blow some time later (hours or weeks). You are taking a big gamble.

There are technical reasons why this is the case, which I could go into if anyone really wants, but I have been through it all before in the past if you'd like to search in this forum /forums/images/graemlins/wink.gif

Quasi, modified sine and square waves are good for light bulbs, heaters and vibrators.
 
Re: Inverter question: What is the difference between \"modified\" or

Agree with you totally, have blown loads of kit Laptops (ves more than one) hifi. even a power drill and a hoover.

Plus have blown quite a few inverters which seemed to work sometimes for months.

You get what you pay for.

And yes I do (NOW) sort of understand the differences but it was an expensive learning curve

Always go for PURE
 
Re: Inverter question: What is the difference between \"modified\" or

[ QUOTE ]
Yes please explain,I 'd like to know.

[/ QUOTE ]
non-sinesupplydrawing.jpg
 
Re: Inverter question: What is the difference between \"modified\" or

Thanks for that.I'll get a proper one.Cheaper than a laptop...
 
Re: Inverter question: What is the difference between \"modified\" or

Just spoken with Dell who confirm that all their computers will work fine with modified sine wave. Just ordered one up from Maplins.
 
Re: Inverter question: What is the difference between \"modified\" or

[ QUOTE ]
Just spoken with Dell who confirm that all their computers will work fine with modified sine wave. Just ordered one up from Maplins.

[/ QUOTE ]With whom did you speak? There are hundreds upon hundreds of different Dell power suppliers most designed and made by third parties. It would be incredible - unbelievable - that each and every one of them had been designed to work from a non-sinusoidal mains supply!

Furthermore, I blew up the supply to my Dell Inspiron 8600 which blew when I was running from a modified sine - not proof, of course, but some evidence. I called Dell back in 2005 after my failure and they told me that the only solution that they recommend for powering laptops from 12Vdc is to buy the Dell convertor. Others here have posted in the last few months that Dell's convertors are not unreasonably expensive, so one poster said.

Obviously you will do what you think best but my recommendation to folks is to either feed your supplies with sine waves (which is what mains electricity should be) or get your equipment manufacturer's approval in writing (or direct off their website) that using modified sine or square is OK.
 
Re: Inverter question: What is the difference between \"modified\" or

Why do you want a 230V invertor? Your laptop needs a DC supply. To get this from 230V you have some sort of adaptor whicg reduces the 230V down to your required voltage, turns it into DC and probably smooths and stabilises it. On my Sony laptop the adaptor runs noticeably warm, showing that the 230VAC to 19VDC conversion is inefficient. In addition, any 12VDC to 230VAC will also have its inefficiency.

But instead I've bought a Maplin DC-DC convertor, which takes in 12VDC and gives out smoothed and stabilised 19VDC. When it's running it's clearly more efficient than the invertor route, because I can't feel any warmth coming from it. It can give outputs of 15, 16, 18, 19, 20, 22 or 24 volts, one of which ought to satisfy your laptop. I've used it for years with no problems. So I repeat: why go for an invertor?

Oh yes, it cost me about £20 if I remember rightly.
 
Re: Inverter question: What is the difference between \"modified\" or

They are fine for many - maybe even most - but not all. My Dell Inspiron 8600 supply (same as the Inspiron 1501) is quite a complicated little beast with a three wire link down what appears to be a normal coaxial power connector. The pin is one contact, the inside of the cylinder is another and the outside of the cylinder is another. While you can get volts into the laptop, unless some mystical (to me) signal passes from the power supply to the laptop, the laptop runs in slow mode with various functions inhibited - charging is inhibited. I've been down that path and spent a lot of time on it in 2005.

One other problem with a dc-dc converter is if you use a ham or marine SSB radio. The loca rf radiated can send the convertor haywire (did to mine and blew a motherboard, my fault /forums/images/graemlins/frown.gif).

The small extra inefficiency of going from 12> 230V > 19V (or whatever) is pretty small for most yachts unless they have very borderline power systems on board. Since most people like to have a sine wave inverter anyway for 'things', it can make sense to power the laptop direct. That's what we do.
 
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