Is this inverter ok for laptops?

[kinetic]

Hi all,

not really knowing what the definition of 'modified sine wave'
means in the definition of this Jaycar 12v 200W inverter....
I was wondering if anyone had any experience with this unit.
http://www.jaycar.com.au/productView.asp?ID=MI5103&CATID=8&form=CAT&SUBCATID=680

or could advise on another unit suitable for running laptops from
12v battery in the field? (in the <100-200$ mark)

PS I know what sine wave etc means (I'm a sparkie)...I just have not
had experience with these 'modified sine wave' type units.
Is it a rough as guts square wave rounded off....or closer to a sinewave?....
or good enough for the task I describe above...
That's what I'm on about, sorry! :)

cheers,

Steve

[tlgerdes]

Not quite a sinewave

http://www.bdbatteries.com/inverterconsiderations.php

It is more a modified squarewave rather than modified sinewave. They are electically noisey, lots of harmonics.

Go for the pure sinewave, but they are 3 time the price

[erick]

I got a real cheap one and plugged in my laptop power supply. It worked, but the supply gave out quite a buzzing sound! A bit worrying - I suspect its life expectancy was shortened. Finally went for DC-DC converter instead running off my 12V supply.

[DavidTrap]

I got a DC-DC one from Jaycar for $29 recently.

I have run a laptop from a modified sine-wave inverter, but want to avoid the inefficiency of DC-AC-DC conversion and operating "indoor" equipment outside in the dew at 240VAC.

DT

[bojan]

Hi Steve,
it should be OK for laptop (power supply for lap directly, without transformer, rectifies 240VAC into DC as a first step).
The amount of harmonics could be a problem for supplying of audio equipment, and nearby receivers, radios, TV's and so on.
Perhaps, you should not supply your camera from this (again, because of noise).

[MrB]

Like David, I have a DC to DC converter, for the same reasons.
Makes sense to go from 12v to 19v
Silly to go from 12v to 240v.. then from 240 back to 19(ish)

[mithrandir]

I've got a Targus power "brick", and that takes both mains or 12V as input.

Not cheap though.

[kinetic]

Ahhhhhh thanks fellas. You blokes are fantastic.:thumbsup:

I would agree it seems silly to go 12v DC--->240v AC then back to
19v DC within the laptop PS. Probably very inefficient.

I was really sorta only worried about the shape of the square wave
in the 'modified sine wave' types and how well lappy supplies go..

As there hasn't been a wave of 'bloody thing blew up my laptop' stories,
initially I thought they must be fine.

But , yes, I suppose it all comes back to efficiency. You would want the most life in a battery from a remote site. So less steps the better.

Looks like DC to DC it is...thanks guys....off to Jaycar I go :)

ps: Trevor...I'd love to get the pure sinewave job but , yeah they sure are
pricey.
I'd be curious to see just what that waveforem looks like on my CRO.

[tlgerdes]

Well Jaycar offer a 7 day money back guarantee.
Although not obligated to do so, at Jaycar Electronics we appreciate that you may have second thoughts about your purchases and will give a 'Change of Mind' refund if goods* purchased from one of our stores are returned within 7 days
Buy one, measure it and post some pictures. Either that or go into the store and ask them to put it on CRO for you.

[AstroGuy]

Why don't you just ask Jaycar?

In most cases the RMS Power of a "modified sine wave" is less than Squarewave. Originally Squarewave was not recommended for most electronic appliances such as computers because it overdrives their power supplies. They were ok for heaters, some motor driven appliances etc...

Modified Sinewave was is a way to create a more compatible RMS power level of the 240VAC 50hz envelope structure. Primarily created to accommodate most sensitive equipment, such as computers etc...I would say yes it probably is ok, but I don't know how reliable or robust your computer's power supply is, or the drawbacks (if any) of the enviroment you plan using in, so I cannot vouch for that aspect of your question.

All I can say is that your computers power supply will most likely be overdriven a little with "Modified Sinewave" and overheat just that little more than if mains power was used under the same conditions.

Secondly, if used on a hot night or day, the extra heat generated by the computers power supply, may cause it to burst into flames and/or damage the computer or those surrounding it.

If you are going to use it, plug it into the computers plug pack first for an hour or so (without the computer plugged into it) and see if it heats up to uncomfortable levels that are more than usual. If heating up is not an issue , then it may be ok to use it by connecting the PC to it.

Just bare in mind, these devices do not have earth connection, and if compromised out in the field, they could result in human injury.

hoped that helped.


Regards...

[Hagar]

Shouldn't be a problem Steve. Your laptop most probably uses a switch mode power supply which will provide all the filtering needed.

[White Rabbit]

I use something similar to that with no problems.

[kinetic]

Thanks all.........I know, I know....
I went against all the good advice and got this unit instead :)
http://www.jaycar.com.au/productView.asp?ID=MB3594
Well my daughter said it looked cool...and it had a lot more features
useful for our camping holidays, so blame her. :)

It has 400w 'modified sine wave' output, a compressor, jump starter
cables and a work light. 2x cigarette lighter outputs too.
12v 18AH SLA battery inside.

Well I put the CRO on it today and it is a pretty poor sinewave with
some scary switching spikes/transients.
Waveform doesn't change shape noticeably with resistive( incandescent
lightbulb), switchmode power supply (laptop) or a slight inductive load
(hairdryer on cool only)
Ive hand drawn over the 2nd pic to estimate what the sinewave would
possibly be as an estimate......note the spikes :)

Works fine though....I ran a webcam on a Dell laptop this arvo and there
were no noticeable noise issues in LX mode or normal mode.

Steve