If you say so... (giggle) perhaps not quite lucky with that statement, but see what you meant to say

hee ! hee ! hee !

My switches does not need power to work.

 

So what is the expected energy savings costs VS price of the device payback time to break even estimate?

If the ROI is more than a year you're boned on the practicality of the device.

Got any real works numbers to back this project up?

 

As others have said, it's a school project, give the guy a break!

I used to have a device that plugged into the scart connector on a Sky box and would trigger a PVR to record by playing back the IR from the remote control to the PVR.

So whilst it might not end up as a marketable product, I can see that you could have a device which for example cut the power to a TV (and possibly all the other boxes associated with it) when the TV was powered off either by power sensing or by detecting the IR from the remote control. When it receives a Power on signal from the remote control it could switch the power on, wait a short while for the TV to come up and then replay the TV power-on IR signal to cause the TV to switch on, all with one push of the TV remote power button.

 

Limiting the scope is certainly an option for a school project. If your professor agrees, make your smart outlet work for devices that don't need anything but power to turn back on.

Then I believe you could set your device to poll the outlet, by briefly applying power to it, for say 10ms every 3 seconds or some such scheme. The vampire power would be cut by the duty cycle reduction. If an "on" condition is detected by polling the smart outlet could leave the power on. The user would only need to know that a device might require a few seconds to turn on once the switch is thrown.

 

A lot of replies on this thread don't seem to realise the magnitude of the standby power problem. As most of you are based in the US, check this out
http://standby.lbl.gov/standby.html

So give the kid a break - he is trying to solve a real problem.

Old TVs and appliances had a true on/off switch that disconnected the power. Now users want to be able to turn them on/off with a remote control, however this requires that at least some of the circuitry in the device stays operational. As power consumption is rarely considered by the buyer, manufacturers can save money by powering this from a good chunk of the main power supply, and so they leave a considerable chunk of the circuitry running when in standby. My TV/DVD draws over 50W when "OFF". My desktop computer/monitor draws about 35W when shutdown.

Now 1W of standby power represents 8.76kWH a year, so at a power price of 11.4c/kWH, 1W of standby power costs $1 pa. My power price is a bit over 20c/kWH, so being able to really turn of my TV/DVD would save close to $100pa.

This is a case of market failure which could be addressed by government regulation mandating that standby power should not exceed 1W (for example). It may add a dollar or two to the price, but clearly would benefit everyone. In the medium term, look out for solutions like that proposed by the OP.

To the OP, look at adding additional (cheap) sensors such as an IR receiver (you could activate simply when IR codes are detected, a more complex unit could learn the actual on / off codes), light (disable overnight when room dark), microphone (to detect when people have stopped listening), possibly a PIR movement sensor (may be costly). Remember that to pay for itself it doesn't have to be perfectly synchronised with the user but simply to significantly reduce the standby power. To be useful though, it shouldn't annoy the couch potato too much.

 

Then I believe you could set your device to poll the outlet, by briefly applying power to it, for say 10ms every 3 seconds or some such scheme.

The little solid SMPS units that keep the standby mode working in modern electronics equipment would not take that sort of supply power cycling for very long before the whole device decided to never turn on again.

Bad idea.

 

As others have said, it's a school project, give the guy a break!

Interesting concern considering that during my senior projects the practicality of the real life application of our ideas was very much part of the overal grade.

Do they now not care if the chosen project has near zero real life application or even if any level of the practicality of application of the project when doing a senior project?

Oh wait obviously they do being how many billions of our tax dollars get spent every year on government funded AE and energy savings projects and programs that end up ultimately having zero practical return on their invested time effort and money.

Carry on.

 

Limiting the scope is certainly an option for a school project. If your professor agrees, make your smart outlet work for devices that don't need anything but power to turn back on.

Then I believe you could set your device to poll the outlet, by briefly applying power to it, for say 10ms every 3 seconds or some such scheme. The vampire power would be cut by the duty cycle reduction. If an "on" condition is detected by polling the smart outlet could leave the power on. The user would only need to know that a device might require a few seconds to turn on once the switch is thrown.

I think a lot of today's devices would not respond well to that kind of power cycling.

This would also run into problems with many power switches on modern stuff. They often are not the static switches of old, but rather just momentary push buttons. So if the device isn't powered at the time that the button is pressed, there will be nothing to detect the next time that the power is cycled.

The thought I had (but I don't know how harsh it might be on modern electronics) would be to turn the device "off" by putting in a high impedance element (switch in a resistor or a suitably biased FET) so that the vampire load pulls the power down to a pretty low level. The question is whether trying to turn on the device in this condition would result in a further lowering of the level that could be detected (and whether this risks damage to the device). I'm far from certain on either point.

 

Yeah, OK, I concede that power cycling would be ineffective or downright bad for too many of the things users would want to use this for.

My point about reducing the scope of the project is still valid. How about limiting it to only old-fashioned wall warts, as an alternative to replacing them outright with a modern SMPS? Unfortunately this ignores the bigger target items; TVs, monitors, and such.

 

Unfortunately this ignores the bigger target items; TVs, monitors, and such.

Actually the 'and such' is where the vast majority of power usage and potential waste is where the big numbers come from.

An average electric dryer draws around 3600 watts and if it ran an extra hour a week more than was needed for the combined loads it dried that one hour of wasted electricity would equal the equivalent of a dozen wall power packs running idle for roughly 10 - 14 days non stop.

My point is one large load device can waste more power in one hour than a dozen smaller devices may waste in two weeks.