# led power draw

Discussion in 'General Electronics Chat' started by tpas23, Apr 8, 2008.

1. ### tpas23 Thread Starter New Member

Apr 8, 2008
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I am trying to quantify the power draw of a monitor (sony sdm-s204) when it is plugged in and the on-off rocker is in the 'on' position, but its signal source (the computer) is off. In this state a single 2mm LED is illuminated red. The spec indicates that in 'stand-by' mode, the sdm-s204 draws 2.4 watts (vs 58 max) , but I find it hard to imagine that that much power is expended lighting a single LED. i find it convenient to turn on the computer and have the monitor fire up without doing anything else, but my wife worries about energy use over the year and it's getting a little contentious.
Does 'stand-by' describe plugged in w/o signal and is the 2.4 watts accurate? (If so, she's right -20hrs a day, 1.5kw a year adds up)

2. ### Wendy Moderator

Mar 24, 2008
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2,540
The extra draw is more than the LED. Mostly it is the circuitry that monitors the computers video output.

I don't see 2.4 Watts being that expensive though, given that power companies talk in terms of Kilowatt hours. 2.4 Watts X 24 Hours = 57.6 Watt Hours per day. Per year it would be 57.6 Watt Hours * 356 = 20.5KW Hours. I paid 11.2 cents per Kilowatt hour this month (and we have higher than usual electric rates), so at my going rate you spent \$2.30 for the priviledge of standby per year, or 19 cents per month.

Lets talk about a 100W light bulb left on. That works out to 876 KWH per year. At the above price that works out to \$98.11 per year, or \$8.06 per month.

Hope it helps. You may need to get your current electric bill and figure out your prices for electricity to prove your point, but be gentle, there is more than one way of ending a marrage.

3. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
Do you have one of those "night lights" that contain a 7W bulb similar to an old Xmas-tree light?

If so, show it to the wife, and inform her that the night light uses nearly 3 times the power that your monitor does on standby.

I "catch it" when I have the garage lights on for more than a half-hour if I'm not actually in there (I have several 32-Watt flourescent fixtures out there). However, my spouse continually leaves the vanity lights in both bathrooms blazing, along with the closet light on when the door is closed. You can't win an arguement with them, because men have this innate need to use logic to make sense, whereas females are simply out to win the arguement...

4. ### Audioguru New Member

Dec 20, 2007
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I am blamed for "stunting the growth of our garden" by the small amout of sunlight that is stolen by my solar garden lights.

I have two 7W incandescent night lights. I should replace them with LEDs.
All other lights except in the refrigerator are low power compact fluorescent type.

5. ### tronics Member

Apr 16, 2008
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is it a cathode ray tube monitor,there may be other circiuts to with the electron gun involed

6. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
With a CRT monitor, it's likely that the tubes' heaters are kept on at a low current. This would minimize warm-up time along with the thermal shock of being cycled on and off.

However, his monitor is of the 20" TFT LCD variety, so it has no CRT. It would have CCFL's, though they wouldn't have power applied during standby.

7. ### DC_Kid Distinguished Member

Feb 25, 2008
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do you have a cable box? those f'ers are always hot (wasting power) even when it is "off". tell her you now have to either get rid of the cable boxes or they must be plugged into a switched outlet so you can power them off for real when not needed. she'll need to wait until the box boots everytime, so tell her she needs to power-up about 8 minutes before desperate housewives starts....

8. ### nomurphy AAC Fanatic!

Aug 8, 2005
567
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Plug the computer and monitor (and printer/scanner and anything else related) into a power strip, and use the switch on the power strip to turn everything on/off (on power down, once the computer switches off, turn off the strip). You may need to set the BIOS for the computer to turn on when power is applied (rather than pushing the on button).

You may want to get a power strip that also includes spike and power protection circuitry, they're not very expensive.

9. ### tonycova New Member

Jan 12, 2009
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I live in california and my state is having a budgget chrisis so every other night I leave my poirchlight in to help pay for school books or arnolds cigars which ever one spends it first.