Re:Stupid Smart Stuff
by darkmighty on Sunday March 09, 2014 @11:44AM
(#7368706)
The energy requirements are magnitudes away, you could never do that for a "smart" device. By the way, we also have the much older self-winding mechanical watches which harvest body movement; those are pretty reliable and can also run indefinitely without maintenance.
> you could never do that for a "smart" device.
That sounds overly pessimistic. Computing power per watt has improved by several orders of magnitude over the last couple of decades already. Combined with more energy-efficient displays (anyone wants to improve on e-ink?), who knows what we could pull off 5-10 years from now, even without a significant change in battery capacities?
Re:Stupid Smart Stuff
by marcosdumay on Sunday March 09, 2014 @03:20PM
(#7369555)
Well, I opened a calculator to prove you wrong, and guess what?
300K * k * 1GHz = ~4pW
Or, in other words, you are right, we can in theory reduce the power consumption of our computers so much that a current watch will last for a lifetime.
Re:Stupid Smart Stuff
by darkmighty on Monday March 10, 2014 @05:25PM
(#7375788)
Computing power is not the limiting factor. Far more relevant are the display, which has efficiency physically limited by its luminosity -- and we're less than a magnitude away from the limit.
Even disregarding that for e-ink, there's the radio, which is limited by the channel capacity, from which I'd say we're also less than a magnitude away for isotropic radiation.
My Casio watch has two tiny solar panels built into its face. According to the manual, 5 minutes of sunlight each day (or a few hours of indoor lighting) is enough to compensate for normal use, and the battery will last 6 months even without any sunlight.
I've had the Casio for 9 years now. It still works fine, and I've never had to manually charge or replace the battery. The battery does get a bit low in the winter when the watch spends a lot of time covered by thick clothing, but that problem is easily fixed by leaving the watch in the sunlight for a few hours when spring comes.
Sure, it's not "smart", but it can display the time in several different timezones, act as a stopwatch, and even has a button that lights up the display at night (which will probably drain the battery faster). All running off of two solar panels the size of the nail on your pinky.