Author Topic: EEVblog #971 - Zero Standby Power TV - BUSTED!  (Read 30995 times)

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Online james_s

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #25 on: February 11, 2017, 05:59:16 pm »
What about design a power supply where the startup supply for the PWM controller comes from a 5V bias on the secondary side? Then use the 5V from the HDMI input to wake it up. Doesn't work very well with smart TVs, though...

In practice, modern TVs already use very little power in standby.


But where does that 5V come from? Unless you run the HDMI cable over to your neighbor's house and "borrow" standby power from them it's still your power, whether it comes in through the TV's power cord, or the power cord of your BD player or whatever.
 

Offline MasterTech

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #26 on: February 11, 2017, 06:41:05 pm »
IMHO it is kinda interesting to switch something on with the light received from an infrared transmitter even though their examples and demos are half assed.

Sure, it's an interesting chip.
Really? What would be the difference between that chip and a appropriate FET?
 

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #27 on: February 11, 2017, 06:54:27 pm »
But where does that 5V come from? Unless you run the HDMI cable over to your neighbor's house and "borrow" standby power from them it's still your power, whether it comes in through the TV's power cord, or the power cord of your BD player or whatever.
The key is *standby*. Switch the connected device to standby and it would switch off its 5V output, reducing the power draw of the display to an insignificant amount of leakage. In the active state, the power usage of the display itself would swamp out the tiny amount it takes to run the PWM controller.

An easy tweak to reduce the power usage of a display in the active state is to implement an adaptive backlight that actually works well. Some early implementations were very "jumpy" and not very well liked, but it shouldn't be too difficult to implement a good algorithm like what every modern smartphone has nowadays. Going up in difficulty (by a lot) is to replace the white backlight with a RGB one and also remove the color filters, strobing the colors in sequence and switching the LCD in sync. In theory, that would cut backlight power usage to 1/3 but it's very difficult to make it work well in practice.
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Offline Don Hills

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #28 on: February 11, 2017, 08:08:46 pm »
I don't see the chip as bullshit. It does what it says it does. It's just their demo that's flawed. If they'd shown it properly integrated with the TV, and used a TV with internal PSU, it would have been fine in my opinion. Arrange it so that the chip only powers up the IR receiver / decoder, which then decides if the code is for that device and powers up the main PSU.

It wouldn't be very practical as a standalone box plugged inline with the device power. I already have a couple of those. (Mort Bay Standby Killer Switch.)  At least they do learn the IR code for the device power, but they're not goof proof and they do draw some standby current of their own. They do claim it "Saves over 80% power consumption on 42" Plasma TV and set top box." (Assuming 1W for the TV, 7.9W for the set top box.) Where have I heard "80% savings" before?

 

Offline bktemp

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #29 on: February 11, 2017, 08:45:33 pm »
I don't see the chip as bullshit. It does what it says it does. It's just their demo that's flawed.
Yes, it is like the Batteriser: It boosts the output voltage of batteries (so it basically works), but it can't provide the promised 800% increase of battery life (as used for their marketing).

The zero power switch can switch devices on without an auxillary power supply. But it ony works for devices within its supply voltage range where it can use the already existing DC supply voltage for turning on a mosfet. Let's say you want to turn on a 12V device powered by battery, it works fine as shown in their demo.
But for anything mains powered you need to do some level shifting or use some other circuit to switch the much higher voltage. And that circuit consumes standby power. There are ways to keep the losses at miniumum (like the SMPS controller ic Dave found), but it will never be zero. You probably could add a battery or use some other energy harvesting device for providing the initial power to turn the main power supply on, but technically that is not zero power.

Regardless how I think about it, the device and its demonstration is very much like the Batteriser: There are some niche applications where it is useful, but it does not work for every device reducing its standy power to zero.
 

Online rsjsouza

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #30 on: February 11, 2017, 09:04:14 pm »
I went to check the comments on their own video and I saw a response to Mike's comments left a week ago or something. They were bragging about the hudreds of millions times lower current or something.
It was clearly exaggerated marketing.
But all those comments are now gone as they have removed the videos.
One interesting detail is that the DMM on the first demo seems to be set to the 10A range. Given a standby power of 5W, the resolution of the DMM will barely measure the current if it was directly to 240Vac (2mA). At 12V, sure, the 5W would be much more expressive but to claim "zero power" you would need a much more precise instrument (perhaps with your uCurrent).
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Offline Bristol Energy

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #31 on: February 11, 2017, 09:56:41 pm »
Having been Dave-slapped, I've edited the video: https://youtu.be/YQ9py3ArfqI
Let us know what you think please.?
 

Offline firewalker

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #32 on: February 11, 2017, 10:00:04 pm »
Welcome Bristol Energy!

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Offline Zbig

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #33 on: February 11, 2017, 10:36:25 pm »
Going up in difficulty (by a lot) is to replace the white backlight with a RGB one and also remove the color filters, strobing the colors in sequence and switching the LCD in sync. In theory, that would cut backlight power usage to 1/3 but it's very difficult to make it work well in practice.

RGB backlight is nothing new, albeit it's used for reasons other than power saving. Closer matching of the backlight to color filters' spectral characteristics being one of the reasons. Other solutions, as you suggest, do away with the filters altogether. Google "quantum dot display", "Sony Triluminos" for other non-conventional LCD architectures. However, the solution you suggest, to simply RGB-cycle the backlight wouldn't work well in large TV displays. This, too, is being done. My digital still camera's electronic viewfinder works that way and it's called "sequential update viewfinder". It's all fine when you just stare at it spot-on but produces very noticeable (to me) artifacting once you move your eyeball. The effect is similar to DLP-based projectors. Apparently, some people are very bothered by this, some don't really notice it and some do but don't care.

EDIT:
I previously suggested that both "quantum dot" and "Triluminos" are RGB backlight technologies which is not factually accurate. I rephrased my wording.
« Last Edit: February 11, 2017, 10:41:26 pm by Zbig »
 

Offline madires

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #34 on: February 11, 2017, 10:49:47 pm »
I don't see the chip as bullshit. It does what it says it does. It's just their demo that's flawed. If they'd shown it properly integrated with the TV, and used a TV with internal PSU, it would have been fine in my opinion. Arrange it so that the chip only powers up the IR receiver / decoder, which then decides if the code is for that device and powers up the main PSU.

Adding an UB20M to lower the standby power of a TV could be done by modifying the power supply. First we need a controllable power switch at the primary side, which is automatically triggered when the TV is connected to mains. Then we need a cap to store power for some time and a control to keep the cap charged, i.e. triggering the power switch for a few seconds for recharging the cap. The control is powered by the cap. The UB20M can tie into that logic to switch on the TV. But it will never be zero standby power for any mains powered device, just a reduction of it. And with this design we wouldn't need the UB20M anyway, because the cap could also power the IR receiver module plus a MCU. But the UB20M would be handy for battery powered devices with long run times and which could
be triggered by a sensor that creates enough power for the UB20M, i.e. photo diodes, piezo elements and what have you. That only works if the sensor providing power for the UB20M uses the same "input" as the primary sensor of the device.  So a few devices could benefit, certainly not all. It's a niche product.
 

Offline SeanB

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #35 on: February 11, 2017, 11:42:58 pm »
B&O did this in the late 1980's and developed a TV set with true zero power off consumption, though the set itself was a Phillips Vestel chassis ( IIRC) inside the box, with a nearly standard Phillips IR remote control, and a slightly modified Phillips microcontroller board, with just a few tiny changes made to the firmware ,and a single hardware change.

How they did it was to put in a power switch with a 12V solenoid coil to release it, and then put in into the OSD menus as power option, which would either put it intro low power regular Vestel board standby ( power supply would turn all outputs down to a low voltage, the microcontroller would use the I2C bus to disable the tuner, horizontal and vertical oscillators and mute the audio amplifier IC, the power supply running in a hiccup mode to maintain a low voltage on all the rails, the micro being powered from the 36v audio rail via a high voltage rated 7805 regulator) or in the true off state the micro would put the Tv into power off, and then trigger the coil on the power switch to disconnect power from the mains input entirely.

There was also an auxiliary contact on the switch, which made only while the switch was pressed, not while it was latched. This was connected to the microcontroller so it could, on power up, tell if the power had gone out ( thus start up the set in standby) or if the power switch had been pressed, and turn on the set like it had been commanded on via the remote control.

These were touted for use in places like hotels or such where they could be off for long periods, and you wanted the power saving, or for those who did not want the red standby light on all the time.  Free with this control came a timer, so you could turn off the set automatically at night after you fell asleep.
 

Offline nctnico

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #36 on: February 12, 2017, 01:13:20 am »
IMHO it is kinda interesting to switch something on with the light received from an infrared transmitter even though their examples and demos are half assed.
Sure, it's an interesting chip.
Really? What would be the difference between that chip and a appropriate FET?
For starters: a well defined on/off voltage. If you use a single FET and it turns half way on with a large-ish load then it will release it's magic smoke and/or the load will get stuck in an undefined (power draining) state because it isn't switched on properly.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline MasterTech

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #37 on: February 12, 2017, 01:34:41 am »
For starters: a well defined on/off voltage.
Does the UB20M have a well defined on/off voltage?

Quote
If you use a single FET and it turns half way on with a large-ish load then it will release it's magic smoke and/or the load will get stuck in an undefined (power draining) state because it isn't switched on properly.
The UB20M does not turn on the load, remember it has a open drain output (oh, just like the drain pin of a FET!) , it needs another device like a P-channel FET to turn on the load with the always present 12V.
 

Offline nctnico

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #38 on: February 12, 2017, 01:41:18 am »
For starters: a well defined on/off voltage.
Does the UB20M have a well defined on/off voltage?

Quote
If you use a single FET and it turns half way on with a large-ish load then it will release it's magic smoke and/or the load will get stuck in an undefined (power draining) state because it isn't switched on properly.
The UB20M does not turn on the load, remember it has a open drain output (oh, just like the drain pin of a FET!) , it needs another device like a P-channel FET to turn on the load with the always present 12V.
You are trying to find downsides which aren't there. The creators should have showed a battery powered device instead of a TV which runs from 12V and needs an extra FET. I didn't check the datasheet but it is reasonable to assume the open drain output can be used as a power switch directly. You don't always need to switch the positive supply voltage.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Hensingler

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #39 on: February 12, 2017, 02:05:57 am »
You are trying to find downsides which aren't there. The creators should have showed a battery powered device instead of a TV which runs from 12V and needs an extra FET. I didn't check the datasheet but it is reasonable to assume the open drain output can be used as a power switch directly. You don't always need to switch the positive supply voltage.

Then maybe you should have checked the data sheet. Abs max output rating is 5.5v and 7mA. Thresholds are not well defined either, nothing but typical values.
 

Offline nctnico

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #40 on: February 12, 2017, 02:20:44 am »
7mA is more than enough for many battery powered (sensor-ish) devices.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline timb

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EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #41 on: February 12, 2017, 03:17:03 am »
7mA is more than enough for many battery powered (sensor-ish) devices.

It's used to control a MOSFET which could handle much more than 7mA, so that's not even a limitation. (I.e., the Open Drain output can sink a max of 7mA current.)

The 5V limit isn't much of a limit either, since you'd likely pull up the MOSFET's gate with a high value (1M to 10M) resistor, which means you could use a 12V or higher source for said pull-up and most likely not run into any issues (since the current would be in the uA range, it wouldn't hurt the chip despite it being above the absolute maximum voltage ratings).
« Last Edit: February 12, 2017, 03:19:34 am by timb »
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Offline Cerebus

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #42 on: February 12, 2017, 04:13:06 am »
The only thing that is relevant is the total power consumption, the TV is not much use without the adapter.

That said, I've noticed that the standby consumption of quite a few modern TVs is extremely low. My 60" LCD consumes something like 1W in standby IIRC. Some older gear was ridiculous, I have a powered subwoofer that draws a whopping 18W in standby, exactly the same as it draws when it's on and idle. I'd had it for over a decade by the time I realized this and a quick calculation determined it had consumed around 1MWH in standby over the period I'd owned it.

Depending on your utility prices and how good a subwoofer it is, you could have paid for it twice.

When I rewired my living room a few years back I put in separate unswitched sockets on their own circuit for all the AV gear and put a 30A switch next to the light switches. Standby consumption zero (except for the PVR on another circuit, so that it can still record when everything else is off cold).
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Online james_s

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #43 on: February 12, 2017, 04:28:29 am »
The only thing that is relevant is the total power consumption, the TV is not much use without the adapter.

That said, I've noticed that the standby consumption of quite a few modern TVs is extremely low. My 60" LCD consumes something like 1W in standby IIRC. Some older gear was ridiculous, I have a powered subwoofer that draws a whopping 18W in standby, exactly the same as it draws when it's on and idle. I'd had it for over a decade by the time I realized this and a quick calculation determined it had consumed around 1MWH in standby over the period I'd owned it.

Depending on your utility prices and how good a subwoofer it is, you could have paid for it twice.

When I rewired my living room a few years back I put in separate unswitched sockets on their own circuit for all the AV gear and put a 30A switch next to the light switches. Standby consumption zero (except for the PVR on another circuit, so that it can still record when everything else is off cold).

My power is relatively inexpensive, about $0.08 per kWh, but it still adds up over time. It was not a particularly expensive subwoofer but it's not crap either. I still use it but I have it connected to a power strip that I shut off when not in use. I have the same arrangement on the TV and related stuff down in my rec room, it's on a power strip with a switch.
 

Offline Razor512

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #44 on: February 12, 2017, 06:41:14 am »
In thinking about it more, it might work if a TV or product was built around the chip. For example, a toggle where you enable the super low power standby mode, the TV will switch to that circuit, and then change a setting where the TV will automatically turn on when it receives power, thus that single button press, handles everything.

Overall, their product needs to be integrated into something else.
 

Online james_s

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #45 on: February 12, 2017, 06:45:29 am »
I just don't see it as being necessary anymore. Standby power used to be a real issue and it was not uncommon for devices to consume 5-10W or more in standby but spurred by Energy Star requirements and greater awareness this is not really an issue anymore. Standby power on modern devices is extremely low, some are less than 1 Watt. There are diminishing returns on efforts to reduce it further.
 
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Offline Razor512

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #46 on: February 12, 2017, 06:56:57 am »
I wonder, how does it react when powering a device off? For example, suppose it is a device which saves log files to flash storage during the shutdown sequence (like with some entry level NAS devices, and routers), does the circuit wait for the load to drop below a certain threshold, or does it simple toggle on when one pulse is given, and then toggle off when another pulse is given?
 

Online mikeselectricstuff

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #47 on: February 12, 2017, 07:00:01 am »
Having been Dave-slapped, I've edited the video: https://youtu.be/YQ9py3ArfqI
Let us know what you think please.?

The problem is it still has a TV in it, so you're is still using an application for which this is just not an issue, just like any mains powered device. It just doesn't matter if it draws a picowatt or a milliwatt. The PSU is always going to be using much more.
If you really want to make a claim of  near-zero power TV, look at integrating your device  into the switchmode PSU primary side.

The device only makes any sense on devices with extremely low available power -tiny batteries or harvested power.  And even then it's only going to be useful in a small percentage of those devices that can't do just as well using low duty cycles or standard discrete devices.
Even with the smallest battery, battery shelf-life is likely to be more of a limitation, so again, it doesn't matter if it's picowatts or nanowatts.

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Offline Cerebus

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #48 on: February 12, 2017, 07:07:25 am »
Standby power on modern devices is extremely low, some are less than 1 Watt. There are diminishing returns on efforts to reduce it further.

Don't forget Dave's point though, that 1W often represents 3-5VA in generation and distribution capacity. So, that's another 1.5MVA to 2.5MVA of generation capacity for each appliance on standby per household for a population the size of London (500,000 households). That's enough for another 1000+ households in total.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Offline ScottK

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Re: EEVblog #971 - Zero Standby Power TV - BUSTED!
« Reply #49 on: February 12, 2017, 08:27:52 am »
I have a zero standby power device for AC line powered equipment here: (It can even work from your couch if made long enough)



On a side note, the Youtube video within a Youtube video confused me for a couple seconds as the red time bar wasn't moving yet Dave was still talking.

That's actually not a zero standby power device, even if the circuitry draws no power. The dissipation of 6ft of typical power cord at Dave's 240V is around half a milliwatt (measured it long ago here in the US (120V) and have used ~20uW/ft as a guess ever since). There's little benefit in setting the standby power bar lower than that for a mains powered design.
« Last Edit: February 12, 2017, 08:29:49 am by ScottK »
 


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