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An Inventor Wants One Less Wire to Worry About

nytimes.com

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Re: An Inventor Wants One Less Wire to Worry About

#51

Post by vacri »

hkmurakami wrote: post #35

Most of us here are discussing the science of this thing. But let's just say that the science somehow miraculously works. Would any of you actually want to buy that big square thing and put it in your rooms? I can't imagine I would.

I don't hate wires so much that I want to be bathed in high-power ultrasound.

And you know what, I have an invention that means your laptop will continue to work in almost any position - you won't have to keep a clear view between charger and laptop. You can turn around, lie down, have a colleague stand over your shoulder. There are some limits, sure, but it gives you a fair bit of freedom to move, and it allows a ton of power to be more effectively transmitted along its full length (with negligible loss), and you can use it anywhere you can find consumer power. It's called a 'wire'.

Re: An Inventor Wants One Less Wire to Worry About

#52

Post by VLM »

gibybo wrote: post #37
Kurtz79 wrote: post #36

Earlier quoted context omitted.

Yes, the radio solution is what I read about in the past. The amount of power needed would really depend on the device and the application, I guess. How many mW are we talking about, in the best case scenario ?

I found some napkin math on stackexchange: http://electronics.stackexchange.com/questions/4664/stealing... One of the answers has the following math: For a large radio tower (100kW), you'd get roughly 80 W per square meter of receiving antenna area at 100m distance. Since the typical distance to a nearby radio tower is probably more like 5 miles, we can reduce that to ~12mW for a 1m^2 antenna. For the size of a phone…

As an off the cuff engineering estimate an AM crystal radio is pretty efficient internally and just barely converts a multi kilowatt transmitter output into barely audible sound inside an earphone, given a substantial antenna and grounding system. So for multiple closer antennas, and something much more electrically demanding than a crystal radio, like a smartphone, its believable.

The biggest problem is going to be PR. So wifi milliwatts of microwave power tens of feet away make hypochondriacs and conspiracy theorists think the government is controlling their thoughts using radio waves... I'm guessing "tens of watts in a ISM diathermy band" is going to substantially encourage them.

Re: An Inventor Wants One Less Wire to Worry About

#53

Post by VLM »

zerohp wrote: post #29
javajosh wrote: post #15

At first I felt awful because I was thinking like part of the establishment: there's no way she came up with something that will replace power cords. I've got a degree in physics, and have always been interested in acoustics, and sound in air has some amazing properties, including the ability to transfer non-trivial amounts of power, especially at nodes, and especially when focused with, say, a parabolic reflector..…

I think that the reason this new idea came from someone outside of Physics or Electrical Engineering is because its poor efficiency is obvious to people with a background in those fields. Sometimes it takes an outsider to challenge assumptions and achieve a breakthrough, but I don't think thats going to happen in this particular case.

"its poor efficiency is obvious"

Train everyone in a discipline that everything must be green. This idea of turning perhaps 99 watts into heat and 1 watt into battery charge is terribly non-green. "Everything must be green" is the cognitive filter which had to be overcome.

In cold climates, especially if you have electric heating, turning electricity mostly into heat is not as much of a loss as you'd think, anyway. In areas of Canada with cheap hydro and electric baseboard heating, its probably a great idea.

Re: An Inventor Wants One Less Wire to Worry About

#54

Post by VLM »

cma wrote: post #49
iyulaev wrote: post #48

Did anyone else read this and immediately wonder, "how many watts?" 1.5 pages of prose and no hard numbers. Years in the industry reading marketing white papers and such cause things like this to really set off the bullshit detector. I'm not saying it's not possible, but, just give me the power (in watts) that is being transmitted by a prototype device. If you don't put that number as a feature bullet, I automaticall…

I was wondering about the watts for a different reason... From Wikipedia: "Although the long term effects due to ultrasound exposure at diagnostic intensity are still unknown,[24] currently most doctors feel that the benefits to patients outweigh the risks.[25] The ALARA (As Low As Reasonably Achievable) principle has been advocated for an ultrasound examination — that is, keeping the scanning time and power settings…

I would imagine the doppler effects of beaming a couple watts at a low freq thru a ceiling fan would be humorous.

Another interesting one is phase noise and distortion and crossover distortion (if you use a simple class-B amp) means you can send a sine wave into a high power amp, but the amplified noise level at audible range might be icky. As a personal anecdote I've noticed this with commercial ultrasonic cleaners. Sure... noise level might be 30 dB down at audible range, but pump a 100 watts at 40 KHz into it and I'm listening to 0.1 watts of noise at audible freqs which is quite loud indeed. Theoretically ultrasonic cleaners should be inaudible, but high powered ones are not. Much as intermod distortion is hilarious with high power RF, noisy/corroded/semi-faulty ultrasound could be loud as heck acoustically thru no fault of the generator, amp, or transducer.

Re: An Inventor Wants One Less Wire to Worry About

#55

Post by iyulaev »

VLM wrote: post #54
cma wrote: post #49

Earlier quoted context omitted.

I was wondering about the watts for a different reason... From Wikipedia: "Although the long term effects due to ultrasound exposure at diagnostic intensity are still unknown,[24] currently most doctors feel that the benefits to patients outweigh the risks.[25] The ALARA (As Low As Reasonably Achievable) principle has been advocated for an ultrasound examination — that is, keeping the scanning time and power settings…

I would imagine the doppler effects of beaming a couple watts at a low freq thru a ceiling fan would be humorous. Another interesting one is phase noise and distortion and crossover distortion (if you use a simple class-B amp) means you can send a sine wave into a high power amp, but the amplified noise level at audible range might be icky. As a personal anecdote I've noticed this with commercial ultrasonic cleaners.…

Did not consider this. Intermodulation and other distortion by-products are going to be difficult to control although I have no experience with the performance of modern amps for sub-MHz frequency ranges.

Building a working prototype that can beam ~1W (or even 100mW) a few feet would be very interesting and would do a lot to lessen my skepticism.

Re: An Inventor Wants One Less Wire to Worry About

#56

Post by tommoor »

etrautmann wrote: post #13

I'd be curious to see a graph of transmission efficiency vs. distance. The technology here is almost certainly acoustic beamforming, and that large square under wraps in the image is an array of small ultrasonic piezo speakers. Beamforming will give you better than 1/R^2 relationship between power and distance, but probably nowhere close to linear. I'd be hard pressed to imagine this working over distances larger tha…

The other thing is that this is probably still transmitting sound when there is nothing to charge? Which would be probably even more of a waste than any transmission efficiency

Re: An Inventor Wants One Less Wire to Worry About

#57

Post by saraid216 »

javajosh wrote: post #15

At first I felt awful because I was thinking like part of the establishment: there's no way she came up with something that will replace power cords. I've got a degree in physics, and have always been interested in acoustics, and sound in air has some amazing properties, including the ability to transfer non-trivial amounts of power, especially at nodes, and especially when focused with, say, a parabolic reflector..…

> I was feeling really bad about myself, but then I realized: without such skepticism the surprise and delight of proving others wrong (not to mention being proved wrong) would be lessened, and so my skepticism does serve a useful purpose, and I could go on living with myself again. This is one skeptic who's hoping that he's wrong and that the inventor is right!

/song

  The world needs people like you and me
  who've been knocked around by fate.
  'Cuz when people see us, they don't want to be us,
  And that makes them feel great!
  We provide a vital service to society
  You and me!
http://www.youtube.com/watch?feature=player_detailpage&v=8Q4...

Re: An Inventor Wants One Less Wire to Worry About

#58

Post by aa0 »

nwh wrote: post #43
tocomment wrote: post #28

Here's what I've been wondering. A transformer provides very efficient wireless power transmission but on a few centimeters. Has anyone considered scaling up a transformer? Would that increase the range? What if we made a house sized one and buried it under the house? Could that provide wireless electricity to the whole house?

You'd still be battling the inverse square law. Wireless power is just too inefficient to ever be used for serious appliances.

You wouldn't if the whole house is metallic would you?

Re: An Inventor Wants One Less Wire to Worry About

#59

Post by EEGuy »

svantana wrote: post #23

I wonder about the health aspect of this. It seems there is very little known about long-term exposure to high intensity ultrasound. Also, there could be a risk of ear damage if a non-linear material came into the sound field, and producing distortion artifacts in the audible frequency range - given that about 1W/m^2 can be enough to cause damage.

This, svantana.

My dentist's ultrasonic dental plaque removing tool produces audible squeals reminiscent of analog tuning of an AM radio. That's one possible example of probable nonlinearities (in my gums an teeth) producing detectible audible power from ultrasonic energy transmission. No reference -- it's just what I hear every time I have my teeth cleaned.

Granted an ultrasonic water stream (dental application) has different physical characteristics than an ultrasonic air pressure wave (ultrasound).

Re: An Inventor Wants One Less Wire to Worry About

#60

Post by acadien »

tommoor wrote: post #56
etrautmann wrote: post #13

I'd be curious to see a graph of transmission efficiency vs. distance. The technology here is almost certainly acoustic beamforming, and that large square under wraps in the image is an array of small ultrasonic piezo speakers. Beamforming will give you better than 1/R^2 relationship between power and distance, but probably nowhere close to linear. I'd be hard pressed to imagine this working over distances larger tha…

The other thing is that this is probably still transmitting sound when there is nothing to charge? Which would be probably even more of a waste than any transmission efficiency

It would be trivial to build in a sensor that detects when a device that needs charging is within range.
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