How green is my green electronics ? Now with improved threshold detection !

Are electronic devices really in a very low power mode when on stand-by ?
Also, how much energy am I wasting for powering devices when not in use ?

I wanted to check it out and decided to build a device capable to detect stand-by mode of my electronic devices and start metering energy used. All this had to be done automatically without my intervention. Metering would start upon entering stand-by and stopped upon exiting.
To do so I needed an energy meter and a current gauge to monitor the current of mains supplied devices and start/stop metering.
For the meter I first looked for silicon, of course. Energy metering is a hot issue with a lot of chip makers and many of them supply cheap solutions.
The project was proceeding when recently I was lucky enough to find two electromechanical meters at a local special trash collecting center (electrical, white goods, furniture).
Actually there should be a plenty of these scrap meters available here as the local electric company is replacing these meters with remotely controlled electronic meters.
I took them along with two VCRs and a printer. The first meter I opened and dismantled to satisfy my inner primary need. The second meter I decided to use in place of the silicon-based one; also, the ready made electromechanical meter solved the calibration issue.
This PopSci contest made me hurry and change priorities in my to-do-list, so here is my design.
Schematic V0.2 is an improved version of the electronic control box over the previous one. I added a potentiometer to set the hysteresis level. This helps discriminate power on vs. stand-by for noisy power supplies like some switchers are. This also helps get firmer metering on/off states.
The schematic shows in red the differences with respect to previuos version.
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saadsms2 years ago
thank you
adam130134 years ago
How much does it really matter anyway when our clothes dryers, toasters, cook-stoves, ovens, refrigerators, irons, blow dryers, and air conditioners all draw 1 KW or more (mostly more)?
Good instructable on building an AC current meter, though.
green is a red herring. there is nothing green about electronics. I propose a title correction! How energy efficient are my electronics projects?
(removed by author or community request)
5Volt (author)  DELETED_dannydutton6 years ago
I understand, the device requires too much work compared to (possibly cheaper) digital devices on sale ! I would never make it either (again !).
It was a sort of divertissement.
The plugs here are very safe as it is practically impossible to come in contact with the live metallic part while plugging in. Also, the sockets in the wall require that all three contacts enter the socket at the same time thus preventing young experimenters from putting wrong things in the socket.
The female (right) can accept 16A larger holes and 10A (smaller holes) plugs. Ground is center and there's no polarity (Line and Neutral can be exchanged). We run on 50Hz while US and some other countries run on 60Hz.
As we run on 220Vac, for a given power requirement we use smaller cords (less Amps are required).
Hola !
Davvik 5Volt6 years ago
That does seem a lot safer than our American outlets, Because like sometimes if you are plugging in an electronic device and your hand slips you will get a nasty shock.
gormly Davvik6 years ago
Davvik no offense, but you are seriously mistaken. It make look safer (and cooler) but really it is no different, it is almost impossible to shock yourself if your "hand slips". It is safe by design. I am a certified electrician and I have worked in electric work shops for 20 years and I have never, ever seen or heard of someone electrocuting themselves with improper use of an "American" style plug.
Bad Maxx gormly4 years ago
WOW! I beg to differ, no offense intended but:

"CPSC document number 524 Electrical Receptacle Outlets" "Electrical receptacle outlets in walls and floors may present shock and electrical fire hazards to consumers. The U.S. Consumer Product Safety Commission estimates that 3,900 injuries associated with electrical receptacle outlets are treated in hospital emergency rooms each year. Approximately a third of these injuries occur when young children insert metal objects, such as hair pins and keys, into the outlet, resulting in electric shock or burn injuries to the hand or finger. CPSC also estimates that electric receptacles are involved in 5,300 fires annually which claim 40 lives and injured 110 consumers........"

So if only 1/3 of the 3900 annual injuries received from electrical receptacle outlets are children, it is fairly safe to assume the remaining 2,601 shock receivers would indeed be adults using an outlet and through some type of mishap were indeed shocked, if not worse. 

 I know in my lifetime I have received two electrical shocks from "slipping" down to the metal prongs while plugging into an electrical outlet, and I know of other people who also have done so, I only mention this as none of us ever reported these incidents to anyone! This despite the first incident knocking me unconscious while plugging in a lamp while reaching behind the couch to do so.
hcold gormly6 years ago
Arr, when I plug in our CRT TV into a multi board sometimes I notice a bright white/blue flash under the plug. I have also noticed this while plugging in a light to a completely different multi board in a different room.
static hcold4 years ago
An arc is most common when unplugging a device that's turn on, but not unheard of when plugging the same in.
5Volt (author)  hcold5 years ago
Oops ! I notice your comment quite late and thanks to Derinsleep reply...
Sorry for overlooking.
Anyways, the blue flash you noticed is pretty common and is due to a very interesting (geek-ly speaking) physical law, the lenz' law where when an inductive circuit like those with motors or large transformers (like the ones in TVs) or some large light bulbs is connected or disconnected from power a large voltage is generated with the white/blue spike you saw.
Physically speaking, the magnetic field generated by the inductive circuit (the motor, the bulb, the transformer) opposes to changes when the circuit is opened or closed generating a reverse voltage such that the current associated to the voltage and the circuit will be such that the flux it creates opposes the change in flux that created it ( quoting wikipedia in part)
Hope this helped
Derin hcold6 years ago
arcing,not that important,I just kick the power bar and my TV works again!
Derin gormly5 years ago
aka NEMA
Davvik gormly6 years ago
I say American but I meant North American, I'm from Canada, and I've never really electrocuted myself, I've just shocked myself because I wasn't paying attention when plugging something in. and a lot of my outlets are broken and very unsafe, so it might just be because my house is old.
Derin 5Volt5 years ago
Hmmm,they don't need the center pin since I can plug my laptop that has the other euro plug into the italy outlet. Italy is awesome,by the way.
5Volt (author)  Derin5 years ago
Ciao D., sorry for not replying earlier but I was on a trekking vacation and couldn't do any Internet stuff. Yes, live and neutral on Schuco plugs are the ones protruding out of the plug handle but plugging it into a regular Italian plug would leave the safety earth unconnected. Also, the diameter of Schuco pins is larger than the italian ones. Oh yes, Italy is awesome as many other countries around the world. Thank you ! BTW, I've just noticed that 'Italy' is not in the Instructbles spelling checker ! :-)
Derin 5Volt5 years ago
That is true for sure,but I saw outlets that can accept both plugs with the earth always connected.
5Volt (author)  5Volt6 years ago
Oops! I meant fewer Amps.
hellcat264 years ago
 se ve interesante este aporte
mrmarshall15 years ago
all of this for a power meter? a hacked GFCI (ground fault circuit interrupter) outlet would give you better results. GFCI outlets work by measuring how much energy goes in and how much comes out, when there not the same it trips.
A GFI doesn't actually measure power/energy, so I'm unsure how a hacked GFI could give better results.  A GFI monitors the current flowing through a circuits line ans neutral conductors. When that currents varies by a preset threshold the GFI assume current is flowing through a human to ground, and trips. That is not to say there aren't components that could be salvage from a GFI that could be used to construct a power meter, but the construction of the circuitry to measure current and voltage will end up very similar to how it has been done here.
5Volt (author)  mrmarshall15 years ago
I'm not sure that a GFCI actually measures anything and what your hack could be. Anyways, why don't you post an instructable on the hacked GFCI ?
im working on it all i have to do is design a circut.(my weak side) in the mean time if you have a broken one or just one laying around take it apart.
Visitor7 years ago
Interesting instructable. Where I live one can borrow a device similar to this "kill-a-watt" meter from the city energy department.

I measured the electricity consumption of my entertainment electronics in the state they are when not used.

  • Monitor (off) 0W
  • Computer (off) 3W (always provides electricity to rear panel USB ports, only keyboard and mouse were attached)
  • ADSL (off) 1W (the mechanical switch is between transformer and the device)
  • Stereo (stand-by) 5W
And also the rarely used bedroom VCR draws 3W when in stand-by.

These are all devices that are theoretically needed only for 8 hours max each day (assuming I spend 8h at work and 8h asleep).

During one year these devices would completely _waste_ as much electricity as a 90W incandescent light bulb does when left on for 1 month (likely more, since I don't need to use all of them for 8 hours every day). Luckily they are all connected with extension cords that are very easily accessible so I can unplug them when I don't use them without causing any decrease in the quality of my life.

Not that I consider quality of life a reason to waste electricity...
Not that I consider quality of life a reason to waste electricity..

Exactly -- now think about it (maybe you have, but for others to see realize this).... Let's say there's one computer per person in the United States (theoretically, 300 million). Each will draw at least 3W (that's an assumption) - That's 900000 kilowatts. For one year, that's 7,776,000,000 Kilowatt hours!

For more perspective - that amount of energy is equivalent to 1,102,000,000 pounds of natural gas ASSUMING we can extract that energy with 100% efficiency (actual numbers are significantly lower). So it's like voting, you're small effort does count - especially if you tell someone else what effect it has :)

All of that so we can keep our computers plugged in and off. And yes, there's some large assumptions there - but even if you divided that in half - that's still a HUGE number. And my significant other laughs at me when I say I'd love to live off grid :P

And to finish off my mini rant... did you know about a third of America's engineers are retiring in three years (at least they're ready to). At the moment, the average engineer work load is something like 47.5 hours per week and rising every year. Of engineers surveyed, ~45% said elementary through high schools get a D or an F for prepping for engineering and prepping for engineering v. other carries. And staggering, 60% said D or F compared to other countries (which means any other country). Luckily the university scores were higher - but, it's still a problem that about half of those that begin in engineering washout typically due to unpreparedness.

Problem: Energy
Question: Who's going to work on this problem?

I dare you - ask a kinder gardener to draw a doctor... then a lawyer.... then ask, draw me an engineer. Here's a hint - one child in that class drew something for an engineer -- a person looking at a car with it's hood up but everyone could draw the doctor and the lawyer o.0

/rant (sorry, it's not directed at you - but energy just gets me fired up)
The problem is actually beyond some of the issues (when we're talking about what's referred to as "phantom power") - the problem is really the low cost of energy versus the high quality of life enjoyed as a result of it.

While I would agree that there is a disconnect between people understanding their energy consumption (in terms of dollars and kWh) there's also a problem with the amount of utility people enjoy as a result of that standby power. They *do* enjoy the ability to turn equipment on by remotes, to come home to an HVACed house set at the temperature that they want, to run large energy-inefficient devices and appliances (look at the prevalence of large trucks in the US and other nations for general transport needs).

When people both have more information on what their using and how much its costing, along with more exposure to the prices of delivering the energy they wish to consume, they will be in a position to make informed decisions on their energy usage. We're a long way from that.

You're absolutely right about the disregard for engineering, but engineers themselves are also to share part of the blame. We need to ensure the community understands what we do and where they receive the benefits of our services. A big part of the problem is the lack of face-to-face time with the community engineers have. Doctors, Lawyers, Accountants etc all spend a lot of time interacting with the community, Engineers generally do not.

Finally, we need to shift people away from being proud of being innumerate and make it something like illiteracy - something that should not be championed.
5Volt (author)  trebuchet037 years ago
As we are approaching the end of the oil age (someone say we are already there) we must keep in mind that oil is a prime matter for a lot of special materials. Burning it into supercars or using it to keep monitors in stand-by may not look very smart in perspective. Energy gets me fired up too. Ciao
Darn, I forgot to include one link... EE Time's on the State of the Engineer
LinuxH4x0r6 years ago
Consider this. The site (google, except black) saved 225,654.349 Watt hours as of September 29 2007 just by being black. Black uses less power on the old school crts. And thats just one site changing it's color! Be Green! - Buy me an LCD ;-)
The articles that Blackle site to back up their claims are old, especially in terms of the technologies available to date.

I wrote up a small article on Blackle and their claims when they first launched. Additionally, the owners of Blackle egreriously claimed (via emails that were forwarded globally) that Blackle was a Google creation and not an entrepreneurial venture using environmental claims as a cover.

End of the day the values that are being claimed are on experimental data from 10 years ago. These need to be rigorously checked for accuracy - as all science requires.

As noted below LCDs use more power to show black (even if only marginally). LCDs are continually backlit (a good portion of the energy goes here) and the RGB components darkened by applying a voltage across each crystal to be twisted to prevent the light being visible.

More interesting will be the energy savings when OLED based displays are widely available at cost competitive prices. Then dark screens really will have the ability to save energy (and money) - and be more efficient than CRTs into the bargain.

and uses more power on lcds
Actually it uses the same
hm a lcd needs power to darken while a crt uses more to brighten.
Azayles Derin4 years ago
Actually most of the power used by an LCD screen is for the back light (whether it's LED or CCFL). The power used to switch the state of the LCD panel itself is so small as to be negligible (it's in the range if micro amps), so for the most part, the power used is the same, regardless of whether black or white is displayed.
However, many modern monitors are utilising a technology which involves dynamically changing the brightness of the backlight depending on whether a dark scene or a light scene is being displayed. This it to give high brightness to light scenes, while still giving good contrast on dark scenes - an overall better gamma throughput.
This means that for these monitors, dark scenes ultimately use less power.
Yes, but in a desktop application it is being powered by a transformer that is always using the same amount of power. What you said is only true in battery powered devices like laptops.
then how does the power save mode work?
duane534 Derin5 years ago
There's a difference between darkening with the LCD and complete black. Think of the electronic method as the dark lines on an Etch-a-Sketch and the power-save as shaking it.
Isn't that when its off? Its sort of like a car. When its not moving it still burns gas in idle.
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