It's is not alternate energy but like to build one

[Hero999]

You're better off looking at the current rating on the power supply, better still use a true RMS meter and measure the AC side.

 

[Thunderchild]

I measured between the 12 DC output and the power conector of the monitor, yes I cut the wire to put in my tester set to amps I measured it as DC, as for the wattage of the CRT I used a refurbished electric board meter the same one used to measure and bill you for you mains power consumption i got it at the electric shop as they are switching to digital meters now and puting the old mechanical ones on the market reset to 0.

 

[Thunderchild]

my LCD power supply does say 100-240 V 1.0 A of course as I said before it draws nothing of the kind

 

[Hero999]

Just because you're measuring DC it doesn't mean that you can ignore the RMS meaurement, if a load isn't drawing a constant current then the reading using a DC meter multiplied by the voltage won't necesarely give you the power consumption. The only way you can gaurantee you're reading an accurate power reading is to use a power meter on the mains side because it will take into account of the power factor which a meter won't.

 

[Thunderchild]

well if you consider most of the power is used by the back light I think thats a pretty constant load isn't it ? as the monitors crystalls are refreshed 60 times a second that's a pretty constant figure it's not an electric car is it I think your being a bit too picky here the fact IS that LCD use a lot less than CRT, also the same power adapter has been used for other things as well, I have also used it to run a fan drawing around 3 amps and it go quite warm at the moment it is cold wile powering the monitor, any other silly exscuses to disbelieve my readings ? how would I measure RMS ? I only have a DC amp meter can I use it for ac with a rectifier in any way ? I could send 220 VDC to the power supply as the AC is getting immediately rectified any way.
Also remember my monitor is an old LCD (3-4 years) so possible comsumptions have even improved

 

[Sceadwian]

A good general rule of thumb is a CRT use around 120 watts of power and an LCD users about 20. There's no need to get any more precise than that

 

[Nigel Goodwin]

A good general rule of thumb is a CRT use around 120 watts of power and an LCD users about 20. There's no need to get any more precise than that

The first is really too high, and the second really too low. Over the last decade or two, CRT set consumption has come down a great deal.

 

[Pommie]

The easy way to measure power consumption is heat. If it's warm it's using power. CRTs are warm LCDs aren't. I can't believe anyone is arguing different. If CRT's were power efficient they would use them on mobile phones.

As for not measuring true RMS. Are there no capacitors in them there power supplies? DC in is normally smooth and so is very close to true RMS.

Mike.

 

[Nigel Goodwin]

The easy way to measure power consumption is heat. If it's warm it's using power. CRTs are warm LCDs aren't. I can't believe anyone is arguing different. If CRT's were power efficient they would use them on mobile phones.

LCD's do run warm - the smaller ones take less power than CRT's, but it's not a huge amount less - and larger ones take more than CRT's.

As for not measuring true RMS. Are there no capacitors in them there power supplies? DC in is normally smooth and so is very close to true RMS.

As you say, measuring DC is the same as measuring RMS - but obviously doesn't account for the PSU losses (but it should be pretty efficient anyway).

 

[Thunderchild]

oh thank you oh gods what suddenly made you change your minds ? I do have to say I erred in comparing the 19" (got mixed up with what the original poster said) I was refering to 17",
My dads 17" CRT as stated by the manual uses 105 W my 15" monitor that is only 0.5 cm (0.2") smaller than the 17" CRT uses 20 watts AT MOST !
now I hate to immagine what that guys kids 19" CRTs are using more like 120 watts each at least so we are looking at 360 W for the monitors before counting 80-120 W for the computers he could easily be using 700 W for his kids computers and then wonders where it goes....

 

[Nigel Goodwin]

oh thank you oh gods what suddenly made you change your minds ? I do have to say I erred in comparing the 19" (got mixed up with what the original poster said) I was refering to 17",
My dads 17" CRT as stated by the manual uses 105 W my 15" monitor that is only 0.5 cm (0.2") smaller than the 17" CRT uses 20 watts AT MOST !

Try comparing like with like! - you're reading the value off the manual for the CRT, but actually measuring your LCD - what does your LCD manual say?, it won't be 20W. My 19 inch LCD says 50W - I haven't measured it, but would expect it to be usually less than that in normal use - just as a CRT will be less than it says in the manual.

now I hate to immagine what that guys kids 19" CRTs are using more like 120 watts each at least so we are looking at 360 W for the monitors before counting 80-120 W for the computers he could easily be using 700 W for his kids computers and then wonders where it goes....

 

[Thunderchild]

well when measuring the CRT with an ex electric boards meter it was 90 or more watts I think

 

[Hero999]

Did you just use a current meter again?

If so you might be incorrect, sure it's using 90VA but it doesn't mean it's using 90W.

 

[Thunderchild]

no for the CRT i used an ex electric board meter so it measured what the electric company will read and charge for

 

[Tim_B]

Going back to the original post on knowing how much energy your using this is a very nice device about to be launched in the UK

http://www.currentcost.com/

I want one!

 

[Tim_B]

In fact I was in the process of doing my own when I can across it.

As a general offer I'm offering my time free for a project that needs coding help if it will have an impact on saving energy and global warming etc

 

[Nigel Goodwin]

Check the last two issues of EPE, they have a suitable project!.

 

[Oznog]

Well, back to the original question:

Voltage and phase MUST be measured along with current to produce an accurate reading. Otherwise you will be including reactive power along with the real power and you only have an interest in real power.

The power company's glass bubble meter uses a mechanical, yet surprisingly accurate mechanism that inherently takes into account voltage, current, and phase angle. Pretty neat, actually. In fact a digital device has to be well-designed and a bit complicated to approach the effectiveness of the bubble.

You can manually read the dials to find you consumption day-by-day, and read you power company's KWH cost to figure out what you use over a fixed time period.

There's a device called a "KILL-A-WATT" meter that Harbor Freight Tools sells now. These are quite nifty. They'll measure the consumption of anything you can plug into a 110V outlet. It'll show real power consumption, power factor, total KWH consumed since it was reset, just about anything you could want. This may even be more helpful than a "whole house" meter because that would not clearly spell out what each device costs. Well, the KILL-A-WATT can't measure your room lights that don't plug in, but then a 100W bulb pretty much takes 100W, doesn't it?

I've measured my PC and monitor. IIRC that thing was well over 200W, pretty hefty cost being left on all the time.

 

[Thunderchild]

and what monitor do you have ?

Just to spell it out to the disbeleiving people that practically called me a liar:

My dads 17" CRT said in the instructions 105 W
My new 19" flat screen in the instructions says 42 W so there you have it straight from the mouth of the manufacturer now am I a liar ?
considering that my monitor has photo and video inhancement ability's that I don't use it is likely that I use less than 42 W or at least I hope so if this thing was green mindedly designed

 

[mramos1]

Shoot was in Harbor Freight today, forgot to look. I will check the web as well. I toy I must have.

Thanks Oznog..