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Author Topic: The uBeam FAQ  (Read 168018 times)

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Offline Fungus

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Re: The uBeam FAQ
« Reply #900 on: July 05, 2017, 10:19:49 AM »
Do people 'charge' their TVs? It seems a weird turn of phrase for somebody who complains about uBeam's grammar.
You never used to charge your phone, either - it had a line for both voice and power.

Yes, but the time we started using the term 'charge' was when phones ran off batteries and needed charging.

People still have fixed landline phones today and nobody says they're being 'charged' by the cables. People will look at you weirdly if you do.
 

Offline PaulReynolds

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Re: The uBeam FAQ
« Reply #901 on: July 05, 2017, 11:32:43 AM »
Do people 'charge' their TVs? It seems a weird turn of phrase for somebody who complains about uBeam's grammar.
You never used to charge your phone, either - it had a line for both voice and power.

Yes, but the time we started using the term 'charge' was when phones ran off batteries and needed charging.

People still have fixed landline phones today and nobody says they're being 'charged' by the cables. People will look at you weirdly if you do.

To continue with your analogy, my use of the term 'charge' refers to the TV equivalent of the modern smartphone, not the TV equivalent of the old landline phone. And yes, that TV equivalent of the modern smartphone does not currently exist, nor is it likely to ever exist. So it's something of a pointless discussion to talk about developing terminology for something that just won't happen. I think I'll move on now to talking about more important things like safety.
 

Offline PaulReynolds

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Re: The uBeam FAQ
« Reply #902 on: July 05, 2017, 11:40:25 AM »
I think this has the potential to drive animals insane, cause depression in pets, effect wildlife, etc.

No matter what the achievable specifications are, this could very well turn your house into a torture chamber for a family pet.



It's rather sadistic.

And now that I've mentioned safety...

Murata style devices tend to work between 40 and 68 kHz so that's all the land based animals on that chart from the raccoon on down it would seem.

Here's an interesting quote from a peer reviewed paper on ultrasound safety for animals and humans. "Effects of Ultrasonic Noise on the Human Body—A Bibliographic Review", International Journal of Occupational Safety and Ergonomics , Volume 19, 2013 - Issue 2

Found here: http://www.tandfonline.com/doi/abs/10.1080/10803548.2013.11076978

"Studies in small animals showed that thermal effects of ultrasonic noise appeared at relatively high sound pressure level. According to Allen, Rudnik and Frings, a mouse dies from overheating after 10 s to 3 min of exposure to a signal of 20 kHz and level of 160 dB [10]. According to Danner, a lethal level for signals of 18–20 kHz for an unshaven mouse were 144 dB and for a shaven mouse 155 dB [21]. Acton obtained similar results and extended studies to larger animals such as guinea pigs and rabbits [22]."
« Last Edit: July 05, 2017, 01:06:55 PM by PaulReynolds »
 

Offline Howardlong

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Re: The uBeam FAQ
« Reply #903 on: July 05, 2017, 10:39:16 PM »
Two or three weeks ago, I extended my experiment with a pair of Murata devices at 40kHz, this time with the matching transmitter/receiver MA40S4S/MA40S4R units, rather than relying on the presumed reciprocal functionality of the MA40S4S for the receiver.

In addition, I used an L293 H bridge driver to produce a 64Vpp square wave signal (~10dB more than the 20Vpp I'd used from my AWG). Adjusting the H bridge power supply voltage, things seemed to be reasonably linear when measuring the Vpp at the receiver, but the driver became pretty warm and the MA40S4S also became noticeably warm. From memory, I measured about 1.5W of power was being supplied from the power supply, so possibly about half that was being radiated as sound judging by the toastiness of the devices.

Anecdotally, my cat (about 12yo) was sitting about six feet away during the tests. He could tell when it was switched on and off as his ears twitched in correlation, but he wasn't otherwise perturbed, which is more than can be said when I play my sax, when he scampers away to the furthest place he can find.

From the technology demonstrations we've seen, it would be reasonable to conclude that the aggregated power is 20 to 30dB above what I was using, and certainly operating close to medium saturation especially with beam forming.

 
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Offline StillTrying

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Re: The uBeam FAQ
« Reply #904 on: July 06, 2017, 03:40:19 AM »
Anecdotally, my cat (about 12yo) was sitting about six feet away during the tests. He could tell when it was switched on and off as his ears twitched in correlation, but he wasn't otherwise perturbed,

After I'd done 40-60kHz 'tests' with the cat (many pages ago), for weeks afterwards I only had to move my hand towards the SG to get the cat to quickly disappear. :)

Online PA0PBZ

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Re: The uBeam FAQ
« Reply #905 on: July 06, 2017, 04:44:51 AM »
After I'd done 40-60kHz 'tests' with the cat (many pages ago), for weeks afterwards I only had to move my hand towards the SG to get the cat to quickly disappear. :)

In ancient times I worked in a Philips store and one of the things I had to do was delivering and installing TV's and explaining the functionality. Sometime in the lifecycle of these products they had an ultrasonic remote, and I remember quite well that while demonstrating the remote the cat that lived there decided to bite me in the back of my head because apparently he was very annoyed by the remote.
Keyboard error: Press F1 to continue.
 

Online djos

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Re: The uBeam FAQ
« Reply #906 on: July 06, 2017, 06:38:40 AM »
After I'd done 40-60kHz 'tests' with the cat (many pages ago), for weeks afterwards I only had to move my hand towards the SG to get the cat to quickly disappear. :)

In ancient times I worked in a Philips store and one of the things I had to do was delivering and installing TV's and explaining the functionality. Sometime in the lifecycle of these products they had an ultrasonic remote, and I remember quite well that while demonstrating the remote the cat that lived there decided to bite me in the back of my head because apparently he was very annoyed by the remote.

Are you sure it was the remote? Cats are funny about who they like.  :-DD

My wife has a black fluff ball that likes me more than it like her.  :palm:
« Last Edit: July 06, 2017, 06:40:17 AM by djos »
The impossible often has a kind of integrity which the merely improbable lacks.
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #907 on: July 06, 2017, 08:09:08 AM »
Someone who has a dual output FG should drive two US transducers a few hundred Hz apart to see/hear if there are positions where the beat frequency is audible.

Offline Gavin Melville

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Re: The uBeam FAQ
« Reply #908 on: July 07, 2017, 01:35:44 PM »
This phone might, just might, be chargeable with uBeam.  Not needing any power is a real step forward. 

http://newatlas.com/battery-lees-phone/50356/

Quote
In addition to the power harvesting problems, the team is also working on how to encrypt messages and stream videos, and adding a low-power E-ink screen for a display.

Video on an E-Ink display - just wondering if the marketing guys have got ever so slightly ahead of engineering.
 

Offline Howardlong

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Re: The uBeam FAQ
« Reply #909 on: July 07, 2017, 06:45:35 PM »
Someone who has a dual output FG should drive two US transducers a few hundred Hz apart to see/hear if there are positions where the beat frequency is audible.

I was wondering that myself, I have quite a few here,  it might make for an imteresting experiment, although I'm not expecting much, even driven hard I don't think I can hit non linearity in air with a couple of transducers.
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #910 on: July 09, 2017, 01:18:50 AM »
Someone who has a dual output FG should drive two US transducers a few hundred Hz apart to see/hear if there are positions where the beat frequency is audible.

I was wondering that myself, I have quite a few here,  it might make for an imteresting experiment, although I'm not expecting much, even driven hard I don't think I can hit non linearity in air with a couple of transducers.

I don't think you'd need any high power to produce and hear the beat frequency, these things seem very loud in the beam at 4m.

Offline Howardlong

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Re: The uBeam FAQ
« Reply #911 on: July 14, 2017, 07:22:15 AM »
Someone who has a dual output FG should drive two US transducers a few hundred Hz apart to see/hear if there are positions where the beat frequency is audible.

I was wondering that myself, I have quite a few here,  it might make for an imteresting experiment, although I'm not expecting much, even driven hard I don't think I can hit non linearity in air with a couple of transducers.

I don't think you'd need any high power to produce and hear the beat frequency, these things seem very loud in the beam at 4m.

I spent an hour or so this evening on this, couldn't hear anything. If I understood acoustics and materials science beyond noob status, I might be able to suggest a means to introduce some non-linearity to mix the signals appropriately. According to the transducer specs, there's not a significant degradation a couple of hundred kHz outside the nominal 40kHz.

I ran one transducer at 39.8kHz and the other at 40.2kHz, with 65Vpp, 80mA total current draw from the PSU. I used a PIC24 to generate the two frequencies from a pair of output compares both running in half bridge mode, fed into an L293 giving two full H bridges, one for each transducer (MA40S4S). The L293 and the transducers get quite toasty!

 

Online edavid

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Re: The uBeam FAQ
« Reply #912 on: July 14, 2017, 07:42:33 AM »
I ran one transducer at 39.8kHz and the other at 40.2kHz, with 65Vpp, 80mA total current draw from the PSU. I used a PIC24 to generate the two frequencies from a pair of output compares both running in half bridge mode, fed into an L293 giving two full H bridges, one for each transducer (MA40S4S). The L293 and the transducers get quite toasty!

This article claims you need > 100dB SPL to get nonlinearity: https://en.wikipedia.org/wiki/Sound_from_ultrasound
 


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