Naked Science Forum

Non Life Sciences => Technology => Topic started by: lean bean on 21/02/2013 16:28:02

Title: Is listening to radio on the tv using less energy than watching a tv programme?
Post by: lean bean on 21/02/2013 16:28:02

Does a tv use less energy when used for listening to radio than when used to watch a programme?

Title: Re: Is listening to a radio channel on tv using less energy than watching a program
Post by: David Cooper on 21/02/2013 18:22:31

I suppose a very dark film might use less energy than a radio station which fills the screen with a bright banner, but then it might use more energy processing the signal for the moving images, so that's a hard one to work out without a lot of knowledge of power usages of screen and processor. There's also the screen type to consider - CRTs and OLEDs will only use energy to light up pixels, whereas an LED backlit display is lighting the whole screen equally all the time, which leads to the other issue of how much energy it takes to switch the pixel RGB LCD filters on and off and whether energy is required to keep them in one of those states.

Title: Re: Is listening to a radio channel on tv using less energy than watching a program
Post by: CliffordK on 21/02/2013 18:45:16

If you control for sound, age of the device, etc, then your TV does more signal processing, and has a larger display, so it should use more juice.

It has been noted elsewhere that it is possible to build a "crystal radio" that is powered 100% by the captured radio waves. 

I don't believe it is possible to do the same with a TV, at least not without a HUGE antenna.

However, as David mentioned, you can also get compact versions of both radios and TVs that use very little power.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fcdn.ubergizmo.com%2Fphotos%2Ftv-watch.jpg&hash=0b56b957a035840d2bc66bd1648edf35)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbp1.blogger.com%2F_76IUaRvRoMU%2FRlHn89b3idI%2FAAAAAAAAAIo%2Fd3TtleOHZPQ%2Fs1600%2Fsubwoffer_stereo_huge.jpg&hash=01d899ebc95142fbf0d689c580e597a1)

Title: Re: Is listening to a radio channel on tv using less energy than watching a program
Post by: lean bean on 22/02/2013 18:13:30

Thanks chaps.
I think whatever that is in the lower picture would make a good alarm clock, especially for me. :)

Title: Re: Is listening to a radio channel on tv using less energy than watching a program
Post by: syhprum on 26/02/2013 16:50:03

The remote control on my LED TV has a button that permits you to switch of the light source when using it as a radio saving a large proportion of the power.

Title: Re: Is listening to a radio channel on tv using less energy than watching a program
Post by: graham.d on 26/02/2013 17:12:33

I would expect the TV to always use more power because, in general, there wouldn't be sufficient incentive to engineer the design to save the power and to do so would increase the cost of design and, probably, also the component cost. However the difference may not be very much if, as alluded to above, the screen backlight and some of the video processing can be turned off. I assume this would be comparing radio received via the digital, over air, channels through a TV aerial with DAB radio. If comparing with FM radio then the radio wins hands down as the digital processing in DAB radio is significant (and not dissimilar from that needed in a TV) and consumes a fair bit of power.