« Bogus Bearings Seized, Cunning Counterfeiters Thwarted | Main | The Sparking Light Switch »

Link This | Comments (21)

Karen Field

Digital Radio Sucks Power While it Sleeps

June 18, 2009

While carrying out an energy audit on the various appliances within his home, Brit Mike Meakin was a little surprised by the power consumption of his year-old digital radio –particularly when it was supposedly “off” or more correctly “sleeping”. How, he asked himself, could it possibly consume some five and a bit Watts while doing nothing apart from being plugged into the socket?

“I had previously noticed that the radio’s mains adaptor got a little warm when it was plugged in. But a quick check on the manufacturer’s website confirmed that this was “normal”. In my mind anything that gets warm must be consuming energy, so I thought to myself “time for some more detailed investigation.”

My bench power supply (carefully set to 9V output) and connected directly to the radio reported a current consumption of about 200mA during normal reception at low volume (1.8W), which only reduced to 140mA when it was “sleeping” (1.3W).

I have heard that digital radios are power hungry and was reminded that my boyhood six transistor radio only consumed about 15mA from its puny 9V, PP3 battery at full volume and did the same thing (well, sort of) as my flashy digital box!

My measured power consumption figures roughly agreed with the manufacturer’s published figures, but I was measuring the DC input power to the radio–not the AC mains input power. The manufacturer appears to have done the same and perhaps conveniently “forgotten” about the power supply losses in its quoted figures?

Digital Radio Power Consumption

	Disconnected	Sleep Mode	Normal Operation	Notes
Specification		1.4W	2.7W
Bench PSU		1.3W	1.8W	DC ammeter
Transformer	2.9W	5.2W	5.7W	AC Power Meter*
Switcher	0.2W	2.1W	2.3W	AC Power Meter*
*AC powered measured with plug-in power meter

The radio is supplied with a (cheap) conventional, copper wire, iron core transformer power supply. Wikipedia informs me that such small transformers may be “‘no more than 85% efficient, with considerable loss even when not supplying any load.” This seemed to be the case as I measured a power consumption of 2.9W when the PSU was not even connected to the radio, and a further loss of about 1W during standby or normal operation. So, in standby, the radio consumed 1.3W and the power supply three times that amount = 3.9W. In comparison, my 32″ LCD television consumes a total of just 2W in standby.

The manufacturer’s web siteboasts of its “Green Credentials” and a May 2009 press release trumpets that its radios “use much less energy than a low-energy light bulb”. While this is true it seems a pity that they don’t use a more efficient power supply with their product.

As an experiment I substituted the supplied transformer power supply with a low-cost, 9V switcher power supply. This reduced the total standby power to 2.1W - easily halving the “wasted” power–albeit at an increased capital cost.

Although these small amounts of power may seem insignificant, multiplied by hundreds of thousand of users it all adds up. Surely minimizing the losses would be a good thing?

I am still curious to know just what the radio is actually doing in this sleep mode. All I can see is an LCD display showing the current time, which I assume requires activity of the radio circuitry to receive time data.”

Posted by Karen Field on June 18, 2009 | Comments (21)

September 18, 2009

In response to: Digital Radio Sucks Power While it Sleeps
TakeALook commented:

Someone at work has a portable Sony Am/FM /CD/Cassette Player that plugs in the wall with a regular plug and not a transformer plug. It has no battery back up, yet it keeps the digital AM & FM stations in memory, even after being unplugged. I always unplug my cell phone charger when not in use. Boy, some transformers stay pretty warm even when the device is in "off".... watch out for those !!!

August 4, 2009

In response to: Digital Radio Sucks Power While it Sleeps
bob13122 commented:

The major problem with copper/iron transformers is that they are designed for minimum cost, which means only enough iron that you're near saturation at peak voltage, and have considerable core losses. Take a 240v/24v transformer and run it on 120v in to get 12v out, and measure the efficiency -- and the transformet temperature. Quite an improvement, but again at an increased unit cost.

August 3, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Gunnar commented:

A low-voltage DC standard may be the way to go as Mac states above. Almost all household equipment runs internally on DC including equipment with motors. The iron core transformer has served us in more than 100 years but it is time to retire it as modern switching DC-DC convertes are smaller and more efficinet. The logistics around such a change is however quite formidable.

August 2, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Radu commented:

With all the disatvantages of old transformers noted above, using a switching power supply for any AM radio (LW, MW, SW) is a very bad idea, given the RF noise figure of any switching converter.

August 1, 2009

In response to: Digital Radio Sucks Power While it Sleeps
William Ketel commented:

The radio continues to draw power when switched to "sleep" mode in order to keep the memory from losing everything. Although it can run on a battery the high draw would certainly discharge them in a fairly short time.
I see the explanation of why it is OK for it to do this in the Jason Voice entry.
BUT the real answer is that the radio is CHEAP JUNK! Memory with a much lower current draw has been available for a long time, but evidently was not considered by the designers of this device.
The real solution to the "vampire power" problem is a power switch in the AC-mains input circuit, ( the AC line input.) The challenge is then that the product becomes much more expensive since now the full 120 VAC enters the product, and must be handled acording to strict rules, instead of being converted to DC outside the box, by a wall-wart certified by somebody else. So it really gets down to MONEY.

July 31, 2009

In response to: Digital Radio Sucks Power While it Sleeps
RayJ commented:

I too did an energy audit around my house with a Kill-a-Watt. The biggest surprise? My Dish TV DVR box - 25W ON, 25W OFF! Apparently the only things that actually powers down are the status LEDs!

July 15, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Jason Voice commented:

Hi
I'm writing in response to the findings posted in 'Digital Radio S*cks Power While it Sleeps' by Mike Meakin's.
While some of the points raised in Mike's article are valid, the piece is generally misleading with regards to PURE's DAB radios and does not provide a fair assessment of the actual situation. It's important to point out that the DAB equipment being referenced isn't entirely reflective of where DAB technology is today, and particularly where we (PURE), the designer and manufacturer of the product used in Mike's article, are at too.
In 2006 PURE undertook a drive to reduce the environmental footprint of all our radio products in the form of a reduction in power consumption (while playing and while in standby), using materials from recycled and sustainable sources, optimizing packaging size, and using components that minimized environmental impact. It set an entirely new standard of design and development within PURE which was named 'EcoPlus' and it was our intention that all future products would (and do) adhere to these new standards. On top of this EcoPlus development was extended to included the redesign and manufacture of some existing PURE products too - like the Élan DX40 used in Mike's article - and it's here where we need to draw attention to a couple of points raised.
The description and readings of the PSU in Mike's article are being taken from the older - pre EcoPlus product but are being cross-referenced and compared to published figures for the newer EcoPlus radios found on our website. One of the many EcoPlus modifications to the Élan DX40 forced a change to the PSU type and it now ships as standard with a 12v switch mode power supply rather than the older 9V linear, non EcoPlus version used in Mike's article - and the difference is considerable (and not because we 'forgot' about power supply losses in our quoted figures). The off-load power consumption of the EcoPlus switch mode PSU is 0.3W rather than the 2.9W stated in the article, and to make easier reading I've broken down the specifications of the two types of PSU under discussion.

Using the linear PSU (9v, 1.5A), non EcoPlus radio used in Mike's article:
PSU OFFLOAD: 2.7W
Standby: 4.95W
Operation: 4.95W (zero volume, for consistency across PSU measurements)

Using the switch mode PSU (12V 0.8A) supply, new EcoPlus radios.
PSU OFFLOAD: 295mW
Standby (energy saving OFF): 2.05W
Standby (energy saving ON): 1.15W
Operation: 2.2W

Mike's findings are mostly correct for the older non-EcoPlus versions of the radio but at the same time highlights exactly why PURE embarked on the new EcoPlus standard of design, and EcoPlus development hasn't stopped either. PURE now test to EN62087:2003 (the measurement for the power consumption of audio, video and related equipment) and many of our products now meet the strict Energy Saving Trust (EST) requirements of sub 1W standby, sub 3.5W operational (with 50mW of audio). If you consider the power requirements of modern EcoPlus DAB products like the PURE Siesta (0.7W standby\ 2.5W operational) and the PURE Evoke-1S (0.7W standby\ 3.3W operational) then you start to see a clear picture of just how far DAB technology has come - and in what is a relatively short period of time.

You can read more about our EcoPlus standard by visiting our website.
Regards

Jason Voice, Technical Support Manager
PURE, Home Park Estate,
Kings Langley, Herts, WD4 8LZ, UK
PURE is a division of Imagination Technologies Ltd.

June 24, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Mike Meakin commented:

Interesting comments. My concerns were the relatively high power consumption for a device in standby/sleep and the poor efficiency of the supplied power supply. But, as commented, cost is the driver !

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Gary C commented:

The average power cost is $.10 per KW/hr.
Which means a 100 watt light bulb costs $.01 per hour (a penny) and your radio cost $.0005 while on and even less when sleeping.
Sure, multiply that by 5 per household and 10 million households in the US and your talking real money.

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
jhankwitz commented:

Switch? Why double the cost of the power supply when it's just as easy to unplug it as it is to flip a switch?

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
DavidPL commented:

Please note that this is not in Califorina, or the USA at all. Look at the plug, not to mention the term 'mains'. I have a CD player/Radio/iPod device that has a very bright display and a bright indicator that goes from green to orange when on standby. There need to be an off option. Note that this device loses all its programming if disconnected.

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
DavidPL commented:

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Petri commented:

If there would be a power switch on those wall warts, who would use it? Even with older analog radios that have the mains transformer inside, the on/off-switch is located usually at the secondary side of the transformer. Therefore the device does take some even when it is switched off. Only way to get more energy efficient devices is by mandating certain specs for those. Off time energy efficiency is possible to do to any device, regardless of it's size, but the added cost is more noticeable in cheaper devices. Then one thing that has to go is transformer, if it is not equipped with primary side on/off -switch.

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
ZZMike commented:

All those DC adapters draw a little power all the time. Industry people call them "vampires" (search for 'reduce vampire power').
The reason is obvious: one side of a transformer connects to the mains. Even if the output side is open, there's a current flow.
Rather than switches, just unplug when not in use. You've got to reach over and get to it anyway.

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
TheMANwithNoName commented:

There are federal efficiency standards (to which I would refer you but this site does not allow links in the post) which apply to wall -warts since a few years ago. It must be either an older radio or illegally imported. The standards do not apply to the standby power of the radio, only to the efficiency and no load consumption of the power supply. California has addressed the 'standby' consumption of entertainment electronics and the manufacturers and some consumer groups are screaming bloody murder. Seems we want to do lip service to efficiency, but not if it raises the cost by a few pennies.

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
TheMANwithNoName commented:

August 31, 2009

In response to: Digital Radio Sucks Power While it Sleeps
TheManWithNoName commented:

I thought there was already an efficiency standard for \’wall warts\’ either in place or being formulated. I believe that there is also an agreement or regulation that these devices consume minimal power when no load is connected to them.

ht_tp://www.powerint.com/blog/mrgreen/great-wall-wart-efficiency-hunt-%E2%80%A2-edit

ht_tp://blog.mises.org/archives/008537.asp

July 30, 2009

In response to: Digital Radio Sucks Power While it Sleeps
TheManWithNoName commented:

June 22, 2009

In response to: Digital Radio Sucks Power While it Sleeps
cvb commented:

you say 'more environmentally beneficial than the whole RoHS debacle.'
Isn't the RoHS 'debacle' keeping heavy metals out of landfills?

June 21, 2009

In response to: Digital Radio Sucks Power While it Sleeps
Mac commented:

The Chinese power supply manufacturers would gladly install those switches if Western companies would request them. The problem isn't with China, it's with Western buyers who are obsessed with cost.
Anyway, the real solution is to standardize on a household low-voltage DC power standard. This would eliminate most if not all of these wasteful power bricks and would be far more environmentally beneficial than the whole RoHS debacle.
Unfortunately it will probably be at least another decade until we see this happen. Sad.

June 19, 2009

In response to: Digital Radio Sucks Power While it Sleeps
MakeItBetter commented:

We need to start demanding China to install switches on the external power supplies. Those little black boxes are big enough to hold one.

Design News Partner Zones

Light Matters: The Unsung Heroes of Modern Health Care
First, let's define "no-compromise." In an ideal configuration, this lamp would use a high-brightness LED (HBLED) that is built into a small, integrated package and is able to produce a large quantity of focused light, operate with a high level of reliability and generate no audible noise. Is this difficult? Yes, but it is possible.
Read More

Design Engineers' Portal for Sensing and Machine Safety
Whatever industry you're in, or whatever product you manufacture, the right sensors to automate your plant, and to improve your overall efficiency, quality and safety are a must. You'll find Banner Engineering to be an amazing resource of products, training and people with expertise.