# Invertors



## 88860 (May 9, 2005)

Has anyone got some basic information to new comers about invertors please. What are the pros and cons and how does one instal them. Can any one reccomend a manufacture. Are they really cost effective. I am thinking about ruuning my Toshiba Tecra 8000 linked to some GPS software on the passenger side for my wife to navigate.


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## 88838 (May 9, 2005)

I think electricity is magic, like Gandalf time,
but
http://www.maplin.co.uk/
i have found these guys helpful in the past


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## 89425 (May 23, 2005)

You asked for basic information?

Well they take in a small dc voltage, usually 12volt to suit our vehicles, and poke out a much larger voltage, usually about 220 - 240 volts alternating at 50 cycles. The more load you want to put on it the more the cost.

However the load is an important consideration with invertors as not all give out a perfect waveform like you would have on a national grid style electrical installation, commonly referred to as 'mains electric'. some are almost square like, others are saw tooth and so on. So before you shell out, do tell the supplier what you intend to run on it, as some invertors will damage the equipment plugged in to it. Cheap is not always best with invertors

If your only running inductive loads, there’s not a lot to worry about, however not strictly in that category, I do run the mobile charger and the power supply to my laptop off mine.
.
.


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## autostratus (May 9, 2005)

Averywildwildcamper said:


> .........as some invertors will damage the equipment plugged in to it. Cheap is not always best with invertors
> .
> .


We wish we'd had your advice before we bought ours.
It did for the toothbrush charger with us.

Gillian


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## 88797 (May 9, 2005)

Steve, couldnt you put a 'choke' inline with the inverter to smooth out the wave? I think I know what Im talking about :dontknow:


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## 89425 (May 23, 2005)

You could add a choke, but ideally you need a scope to check on your results, but invertors are so cheap these days its not worth the hassle, besides experimenting with your new inverter before the warranty is out, isn't recommended.

I still think its best to shop around for the appropriate capacity unit and check its the supplier that their model is suitable, then if something happens the onus is back to them.


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## Anonymous (Nov 10, 2000)

*Cheap Invertors*

I recently purchased a Belkin 300 watt invertor primarily to power the portable colour TV, charge up the laptop etc. The manufacturer's literature said it was fine for these uses but when I used the TV the picture had a green hue across the top of the screen.
I checked both the battery input and the invertor output voltage with a digital multimeter, all was ok. I tried other mains accessories and they were fine.
As this invertor produces a modified wave I can only assume that the TV doesn't like it  I spoke to the dealer who said that some TVs were more suseptable to modified sine waves than others.
It got me thinking, what if it damaged other electronic devices such as the laptop or DVD 
Guess what I'm buying now !! ...an invertor with a true sine wave output. Yes, it's a lot more expensive but for peace of mind it's worth it.

Has anyone else had problems with cheap invertors ? This one cost around £50 and as far as I'm concerned it was a waste of money.

Jim


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## Anonymous (Nov 10, 2000)

I run a 600w cheapie with no problems and use it for my laptop, I admit I get the occasional line across the TV screen but it does no worry me. As for the colour tinge on your screen Jim that sounds more like a magnetic influence and is typical of the degauser not working correctly on startup, from my limited knowlege of the matter I would not have thought it would be the modifide sine wave doing it but more likly to be the extra surge needed for the degauser, hence my reason for useing a 600W.

There must be a TV engineer out there that knows the answer?

Ken S.


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## Anonymous (Nov 10, 2000)

Thanks for the input Ken, 
it sounds quite possible that it is the degauser that isn't working properly on start up , I never thought of that, but it still begs the question why a manufacturer of invertors can say that their product will operate up to a 19 in TV, (mine is a 14 in and is rated at 45 watts. ) when it obviously doesn't take into account of the high surge on initial start up and fails to degause properly. 
Your advice about buying a 600 watt unit is good advice for anyone contemplating buying a unit and using a TV.
Before I posted here I had already sent off for a 600 watt true sine wave unit which I don't regret as I think in the long term will be safer for delicate electronics and give better performance. 
Anyone want to buy a 300 watt invertor, one careful owner, little used .?? .... lol

Jim


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## Anonymous (Nov 10, 2000)

All good advice above.

We started our 'flirting' with inverters by trying a couple of from Maplin. The first one we bought was a 100W 'modified sine wave'. Now although that sounds better than a 'pure sine wave', it isn't! In truth the output's never seen a sine wave, let alone been modified from one! It blew up BOTH of our toothbrush chargers, and overheated trying to recharge our walkie-talkies.

The seond one we bought was a 100W sine wave version, a LOT more expensive but didn't blow anything up. Anyway, we needed more juice for our desktop PC so returned it and went for a 300W Mobitronic sine wave inverter (we sell them on our shop)

We've had NO problems at all with that unit, it's usually very quiet (some load types make a bit of a hum) It's been reliable and is a good German build.

Another thing to watch out for is the continuous load compared with the surge capacity (the Mobitronic is 300W / 600W) A large surge capacity allows item (like fridges) to startup without overloading the inverter. Most are overload protected these days.

Another bit of advice is that inverters run at their most efficient at about 1/3 of their stated continuous load.

Hope this helps


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## majvs (May 9, 2005)

*Inverters - problems, problems!*

:?: Having weighed up the pro's and cons we eventually decided that an inverter would be the best way of powering our new 15" Sharp flat screen TV. 
We bought a Nikkai 600w modified sine wave inverter costing a very reasonable £40+ from Maplins. We were assured that it was more than capable of running not only the TV but also a digibox and a camcorder recharger.
We wired it up to our twin battery set up for a quick test but found to our dismay that it didn't work!
It produced a clicking sound from the TV transformer (240v to 12V) and produced nothing but a blank screen. There was a similar reaction from the camcorder recharger unit which also resulted in a pulsing red light on the camera itself (its normally a steady red light for 3 seconds or so before turning to green to show its charging up)
Luckily there appears to be no damage to either unit.  
Before we return the inverter, I'm wondering whether its the modified sine wave thats causing the problem? Any ideas anybody?


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## Mike48 (May 1, 2005)

We have a 15" Sharp flatscreen also. It runs perfectly on a Moore 300watt modified sine wave inverter. Your 600 watt Maplin must be faulty. Moore inverters are expensive but from speaking to people they always seem to deliver.


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## 89122 (May 14, 2005)

Why not get the Lap Top Power adapter from Maplins and run it of the 12v system.  
It is made by Kerio


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## 88790 (May 9, 2005)

I run my Sharp 15" Aquuos LCD from a cheap 150w inverter, never a problem.

Still beats me that this is a 12v TV and there is not available a lead we could just plug into the 12v suppply! Seems Sharp are missing out here. Surely there must be somebody who can produce a lead for these popular TVs?

John 8)


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## 88724 (May 9, 2005)

Hi 

Buy modified sine wave and it as a few limitations very few but here they are.

It cannot run the toothbrushes, It cannot run Automatic washing machines due to (thyristors) It doesnt like Combined TV Videos (thyristors in the joint power supply)

Occasionally the no name brands version of modified sine wave is bad far nearer to square wave.

I have run the following all from modified Sine wave invertors with no problems(Good brand Sterling, not that dear either)

Fridge full size domestic

Microwaves 3

Heaters (just testing)

Hot water Truma Boiler

HairDryer

Computers several

Chargers many NOT toothbrush

TV 17 " Flatscreen LCD

DVD Player

Paystation 1 and 2

Printers

Fax

There are several ways around the toothbrush Charger charge when hooked up, buy a small Pure sine invertor.

Pure sine wave should be you last resort for several reasons in general use they cost you far more ah (ie batteries flatter quicker) Expensive if they are not the only answer.

Your motto should always be 

Modified (Quasi sine) wave first Choice.

Pure sine wave LAST resort.


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## 88724 (May 9, 2005)

BTW I have recently tested the Cheap Nikkai Invertors from Maplins


150W £14.99
300w £19.99
600w £39.99

Checked most of the above items and again no problems. Now in the last 3 days have had to buy 7 for friends and family!

All definately work OK with sterling Quasi sine wave.


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## 88790 (May 9, 2005)

GeorgeTelford said:


> Hi
> 
> Buy modified sine wave and it as a few limitations very few but here they are.
> 
> ...


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## 88724 (May 9, 2005)

Hi 

No no big auto washer in mine, but it is done in some Yatchs and motorhomes.

George


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## Mike48 (May 1, 2005)

Jabber. 

It is not just a question of a lead to enable a Sharp Aquos to run on 12 volts. I e mailed Sharp on this point some time ago and they informed me that, because of fluctuations in voltage in motorhomes, their particular TVs need to be run through an inverter. 

G


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## Boff (May 10, 2005)

Hi!



Averywildwildcamper said:


> ...If your only running inductive loads, there's not a lot to worry about...


I think you wanted to say "non-inductive loads" here... :wink:

I have a cheap (Taiwan-made) 150 W inverter. It says "modified sine wave", but I haven't checked that with a 'scope yet. (Strange, I actually _own_ an oscilloscope but have not yet thought of it... Will do next days.) So far I have tested it with:

- Laptops (Compaq, Dell and HP, but no Siemens)
- Charger for electric shaver (Braun)
- Mobile phone chargers (Siemens, Nokia, Panasonic, Samsung)
- Digicam (still photo) chargers (Sanyo)
- Portable cassette player (Sony kids version)

No problems occured so far. Except that on hot summer days the inverter goes on overheat with the laptop. And with the cassette player there was an audible hum on the speaker.

Don't know why but it seems that especially toothbrush chargers are sensitive. And I have heard several reports about Siemens laptop power supplies not working on modified sine.

Best Regards,
Gerhard


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## AutoK (May 1, 2005)

jabber.
Did you not get a 12v lead with your Sharp tv when you bought it?

I wouldn't worry too much you are probably just as well using it at 230v
bearing in mind any voltage drop at the 12v socket might cause some problems.

Being in the trade I use a number of companys for spares, you could try contacting CPC in Preston Tel 08701 20 25 30
www.cpc.co.uk
They are mainly for the trade but I think they would be able to supply you with the correct lead. the amount of leads they list in their catalogue is unbelievable just quote your tv model number.
Hope this helps.

AutoK


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## 88790 (May 9, 2005)

There was no 12v lead. I contacted Sharp and they said they did not supply one and I also tried Road-Pro and they said I would have to use an inverter because there was not one.

Thanks for the web site I will have a look.

John :?


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## 88724 (May 9, 2005)

Hi Gerhard

Its probably the Kids electronics causing the hum (ie its not smoothed and filtered as good as a "proper" hifi )


BTW I have tested on an Hifi no probs hum etc.

One other thing didgital timers and clocks are not 100% on quasi, actually they can run fast/slow on Pure sine too.

Hi AutoK

It may not be a good idea to run via 12v anyway in reality to be safe you would need to buy a regulator these cost in the region of £30 £35 for 12v the reason is that when sharp say 12v they mean 12v

a leisure battery that is not flat is 12.4 to 12.9 Volts

The problem doesnt end there tho when on charge eve naff Zig and Plug in systems units put out 13.8volts (I hate calling them chargers, its a falsehood) and a proper charger can be putting 15v in so its not a good idea to connect any electronics that require 12v to a battery

The only time a battery reaches a real 12 volts is when its flat.

Here endeth the Sermon. Matthews Chapter 1 Verse 11


© George Matthews


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## Boff (May 10, 2005)

Hi George!



GeorgeTelford said:


> Its probably the Kids electronics causing the hum (ie its not smoothed and filtered as good as a "proper" hifi )


Yep, that is what I thought as well.



GeorgeTelford said:


> One other thing didgital timers and clocks are not 100% on quasi, actually they can run fast/slow on Pure sine too.


But this is independent of the wave form. Background is that many mains-only clocks use the 50 cps frequency of the mains as time base. This frequency is normally kept very accurate by the power companies. Much more accurate than the inverter will do.



GeorgeTelford said:


> It may not be a good idea to run via 12v anyway in reality to be safe you would need to buy a regulator these cost in the region of £30 £35 for 12v the reason is that when sharp say 12v they mean 12v


Correct. What I do not understand here are the high prices for such a regulator. It is no problem to cut down the van voltage (12.4 to about 15 volts) to precisely 12 volts using a Zener diode (if anybody here still knows what that is... :wink: ). Necessary components from the hobby electronics store would be below 1 quid (including VAT). Quite a margin for the makers of these "regulators".

Best Regards
Gerhard


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## DABurleigh (May 9, 2005)

Jabber,

Although the Sharp Aquos doesn't come with a 12v DC lead, you can purchase one their Spare parts centre.

Sharp Parts Centre - 0161 204 2222
Part number: 12/24VPSAQUOS
Price: £41.20 inc VAT

Dreadful value, but at least you can pays yer money and takes yer choice.

Dave


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## 88724 (May 9, 2005)

boff said:


> One other thing digital timers and clocks are not 100% on quasi, actually they can run fast/slow on Pure sine too.
> 
> But this is independent of the wave form. Background is that many mains-only clocks use the 50 cps frequency of the mains as time base. This frequency is normally kept very accurate by the power companies. Much more accurate than the inverter will do.


Hi Gerhard

I think you may have misread my post, Some digital clocks will not work at all on Quasi sine wave, those that do mey be running fast or slow.

All will work on sine wave, however they may run fast or slow too.

I cannot find a Zener that will cover the low end perfectly but










If we specify : Vin 16v Max
: Vin 12.8v Min
: Required output 12v +- 5%
: Load current 5 Amps

Then we arrive at

Resister = .16 Ohms 100 Watts
Zener Diode =12v 300watts

It also leaves us with the problem of what to do when the charger is off and the battery settles below 12.8 v

The only solution that quickly springs to mind is a relay DP relay that defaults the positive directly to load when charger switched off and when the charger is switched on the positive is fed via the mini circuit.

Any offers or improvements ?

George


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## 88790 (May 9, 2005)

Dave, many thanks, when we got the TV a year ago I phoned Sharp HQ and they said they did not do one. 

Perhaps then if Sharp do one there will be a compatible.

John


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## 88724 (May 9, 2005)

Re the 12v lead

do check that it is a regulator not just a lead.

if it is not beware that any decent charge voltage may destroy the TV, 15v is 25% more than the nominal voltage.

George

PS if you are thinking if they make it it must be OK think again, it may state that you cannot use it ( the lead) while charging, this would preclude any time while on hookup or even driving.


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## 88790 (May 9, 2005)

I am very interested in this idea of the STB and have looked on the net at various boxes. I notice Hauppage do a small box that looks ideal but does not possibly have the feature set of some of the others. It does take 12v and 240v though.

I would be appreciative of your input on the type of STBs and size etc. you have.

Many thanks,

John 8)


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## Anonymous (Nov 10, 2000)

I've had no problems running a slow cooker via a 300 watt inverter.


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## Bazbro (May 9, 2005)

Sorry to interfere with the inverter thread, but in reply to Jabber's post, this STB
http://www.fiammaonline.co.uk/erol.html#1x0&& (go to 'Electrical', then 'Televisions' and it's at the bottom)
seems to have all the features, AND runs on 12v. I've never heard of the make, though, only in respect of 'toilet paper' when it's 'Soft' too! 

Barry


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## 88790 (May 9, 2005)

Many thanks Barry, looks interesting.

I have also found the'Hauppauge DEC 1100T at www.shop.bt.com this is quite small and looks interesting.

When I put it into Google, there is one chap who comes up all over the place saying how pleased he is with it and he is buying one for his father.

This also works off of 12v and has a power pack to plug into the mains.

Once again many thanks for taking the time to find this for me.

John :wink:


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## Bazbro (May 9, 2005)

This DEC 2000 looks good, too - 
http://www.dabs.com/uk/productView.htm?quicklinx=24M4?refererid=t5 
use it at home on the telly, then take it with you in the m/home to use on the laptop?

Barry


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## 88790 (May 9, 2005)

I have ordered that one from BT Shop and will report back!

It is £49.99 post free.

http://www.hauppauge.co.uk/pages/products/data_dec1100-t.html

Watch this space!

John 8)


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## 88790 (May 9, 2005)

Reporting back, got the DEC 1100T and tried it, Wow! nice clear pictures and lots of different stations.

Very small box about 150 x 180 mm. The power supply is a 12v mains plug-in pack, so maybe it is possible to connect straight to the MH supply. The remote is not too directional - it worked even tucked behind the television.

I think we are going to be very pleased with it.

If anybody has one and runs it straight from the MH battery please let me know.

Delivery from BT was next day.

Hope this helps!

John 8)


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## 95144 (May 1, 2005)

so many inteligent blokes talking round n round the truth

its electronics, leave it to the kids.

years ago when me dad were a lad you could call a power supply a transformer with a fair degree of certainty, now days its more likely to be a switchmode power supply. many of thies are quite rough like phone chargers, because there not the charger at all, there the suppy to the charger in the phone and its output need only be higher than needed and lower than meltdown, regulation is not really an issue. 
the shaver charger again is rough and drives a coil with the cheapest electronics possible so if it starts surging it soon kills the coil driver. 
the tv uses switchmode tech to produce many voltages, tv's by nature need good timing, go upsetting it and.......there you go.
hi-fi is very unlikely to be upset, unless you know what hi-fi is, in which case its no good and your mains filter wont touch it.

you can get me a pint when im older


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