
Battery-Free Cell Phone - jacquesm
http://www.techradar.com/news/this-phone-needs-no-battery
======
make3
Related, this spying microphone bug first used by the Soviets in the 50s that
has no battery or electricity wire and can keep listening "forever", which was
discovered by accident in a "gift" eagle sculpture given to the US ambassador,
after years of staying in that embassador's office, listening
[https://en.m.wikipedia.org/wiki/The_Thing_(listening_device](https://en.m.wikipedia.org/wiki/The_Thing_\(listening_device)

~~~
flyGuyOnTheSly
The Thing could not receive transmissions, though.

Which makes this all the more impressive!

The Thing actually needed power to operate, btw. The power was just beamed in
externally.

~~~
chris0x00
As far as prior art on the receiving side lets not forget about good old
fashioned crystal radios
[https://en.m.wikipedia.org/wiki/Crystal_radio](https://en.m.wikipedia.org/wiki/Crystal_radio)

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IncRnd
There were earlier discussions on this.

> _Right now the battery-free phone needs a custom base station to transmit
> and receive calls. But the team says there 's no reason why the technology
> couldn't be integrated into standard mobile network infrastructure._

This could only be called a cell phone, if the cell phone network changes to
accommodate this radio. It's not a cell phone, because it doesn't work with
cellular phone towers.

~~~
chris0x00
I agree calling it a cell phone sets the wrong expectations, but it's still
neat and I think a good application could be an elder care pendant (help,
fallen, can't get up, yadda yadda) where close promity and custom base station
aren't an issue, but never needing to worry about the status of battery would
be a big plus.

~~~
IncRnd
I agree!

Those applications are called medical alert systems, and there are various
kinds. Some of the systems contain GPS, while other work with a radio base
station to inform if the person has fallen and can't get up.

For example,
[http://www.best10medicalalertsystems.com/](http://www.best10medicalalertsystems.com/)

------
jimrandomh
When tech writers write about things they don't understand, they tend to omit
all the caveats, like "cripplingly short range" and "probably illegal to
operate as a consumer device due to RFI".

~~~
userbinator
Probably legal due to the frequencies involved, but also useless in anything
but a completely radio-quiet environment (the ISM bands are specifically
allocated to common interference sources --- and the only reason other
wireless devices like WiFi and BlueTooth can survive there are due to
processing techniques that can transmit/receive below the noise floor, like
spread spectrum.)

~~~
retSava
Even if it operates in the unlicensed freq. bands, ie ISM bands, there are
still limitations to how much you may interfere with others, expressed in eg
duty cycle requirements (ie not sending too long at a time) and energy levels
(ie not sending too strong). That's what the FCC/ETSI/CE etc etc regulations
do.

------
chris0x00
So this uses vibrations caused by our voice to change the effectiveness of the
antenna to absorb power from the base station right? Base station then
interprets the varying current draw as amplitude modulated audio and Bob's
your uncle? If I'm correct (no sure that I am) wouldn't this require being
pretty close to the base station?

~~~
agumonkey
Thinking about this I wonder why there's no kinetic charger.

~~~
bduerst
I'm suddenly picturing a shakeweight or crank cell phone

~~~
fish_fan
I would definitely buy a crank cell phone if I were allowed to clone my sim
(for emergencies).

~~~
radarsat1
[https://www.amazon.com/Peach-Dynamo-Charger-Emergency-
Supply...](https://www.amazon.com/Peach-Dynamo-Charger-Emergency-
Supply/dp/B01NBM5S0C/)

3.99 with free shipping.

------
magnat
> _The biggest step was eliminating the analog-to-digital converter that turns
> your voice into data. Instead, they took advantage of tiny vibrations that
> happen in a microphone when a person is talking into it, or a speaker when
> someone is listening. An antenna converts that motion into radio signals in
> a way that uses almost no power._

Does it mean the voice is transmitted in plaintext using analog modulation of
(reflected) carrier wave? Privacy concerns aside, how can it handle calls from
multiple stations over same frequency range?

~~~
gregman1
Voice is always transmitted in a "plain text" is it radio or phone except if
you use some special device (it's never easy to get one) and protocol (good
luck to access it for cheap).

~~~
Synaesthesia
But GSM is fully digital and encrypted

~~~
locusofself
poorly encrypted

~~~
Synaesthesia
Yes but it’s not just a naked signal of the audio as this is.

------
grizzles
I'd like to try to make a mobile device like this that can run with ~100mA
input power from a solar cell. I thought about using the Particle Photon & an
E-ink display, but my knowledge of hardware isn't the greatest. Any EE out
there think it's possible?

~~~
duskwuff
How large of a device do you have in mind? 100 mA is more than enough power
for the Photon module, but would require a relatively large solar cell --
probably at least 3 to 4 inches square under ideal conditions.

~~~
grizzles
That's roughly the size I was thinking. I was thinking of adding a battery
too, less as a storage bank and more as a way of papering over the ideal
conditions issue.

~~~
KGIII
Have those graphene supercapacitors become commercially available? If so, you
may be able to do without a battery at all. Well, depending on use, available
charge, and efficiency.

------
sly010
Battery-free wireless headset would be a better name I believe.

~~~
exikyut
Wait. Depending on how loud this thing can go, it could be 100% effectively
pivoted as "world's first battery-free wireless headphones". Start a company
selling that and use it to fund R&D to remove the PTT switch from the
communicator design etc.

~~~
p1esk
The main problem with wireless headphones currently is unreliable/lossy
connection, and latency. This would make it worse.

~~~
exikyut
Is this design analog or digital? If it's analog, all those issues are
replaced by static noise, which could very probably be largely mitigated by
amplification power and possibly audio processing on the transmitting side.

------
0xdada
Previous discussions:

[https://news.ycombinator.com/item?id=14659236](https://news.ycombinator.com/item?id=14659236)

[https://news.ycombinator.com/item?id=14716986](https://news.ycombinator.com/item?id=14716986)

------
carlesfe
This is an incredible feat.

It runs on 3.5uW, and the homemade cellphone I built last year with off-the-
shelf components drew 2A when syncing with GSM antennas.

Some people don't realize it, but GSM is very expensive power-wise, especially
on boot when it has to find antennas. Having a device that can be solar
powered or even with ambient radios is extremely useful!

    
    
      Right now the battery-free phone needs a custom base station 
      to transmit and receive calls. But the team says there's no reason 
      why the technology couldn't be integrated into standard mobile network infrastructure
    

Well, there's the trick. But an awesome proof of concept nonetheless

~~~
mkroman
I'm a bit puzzled by the statement “But the team says there's no reason why
the technology couldn't be integrated into standard mobile network
infrastructure”

There's obviously many reasons. Transmission range, security, privacy,
reliability, ...

------
sscarduzio
Here I am in 2017 reading this, and yet I can only dream of an iPhone with a
battery life greater than one day.

~~~
valuearb
Apple is building this so they don’t have to give you a battery at all.

I’m always confused by people complaining about iPhone battery life. My wife’s
iPhone 6 lasts days, it’s called a battery pack. And she gained this
incredible battery life without forcing me to carry a heavier bulkier iPhone.
That’s what Apple understands, making their devices heavier and thicker to
please a minority of users while inconveniencing the majority makes no sense
when battery packs exist.

------
mcdevilkiller
Is this what Tesla dreamt about? It's incredible.

------
flukus
The low power usage of the device is impressive (I think), but the battery
free part not so much. It seems as though this is just the modern day version
of the crystal radio sets many of us built (or tried to) when we were kids.

------
squarefoot
Nice, but then what about a thousand miles using a voice powered transmitter?
[http://soldersmoke.blogspot.it/search?q=El+silbo](http://soldersmoke.blogspot.it/search?q=El+silbo)
[http://qrznow.com/amateur-radio-transmits-1000-miles-on-
voic...](http://qrznow.com/amateur-radio-transmits-1000-miles-on-voice-power/)

------
brownbat
My dream phone would have a small e-ink display that can maybe read wikipedia
or text based websites, simple physical buttons, and a 5000 mAh battery, maybe
even some low discharge chemistry instead of lion, shooting for a charge maybe
once a month.

Naturally GPS would be right out...

Pretty sure the potential market size is in the single digits, but I'd be
happy.

------
CiaranMcNulty
Is this sort of passive device practical for applications such as wireless
mouse and keyboard? It would seem like a great selling point (similar to
Logitech's attempts to make solar powered peripherals)

------
odammit
Looks like it doesn't support snapchat or texting, so Im sure the "festival
goers" aren't going to be doing backflips over it.

I could use this in my spy operations though. Not that Im a spy or anything.

Definitely, not a spy.

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e19293001
I've been wondering. Is it possible to build a logic circuit out of a radio
frequency? If so, it would be possible to build a computer out from it.

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yellowapple
If this is basically push-to-talk, then I wonder if it might have some good
applications as a walkie-talkie / handheld radio?

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DiabloD3
Makes you wonder if this was what was being tested in Cuba that attacked the
diplomats.

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PascLeRasc
This has been posted here earlier and HN couldn't get over how it's not
perfect, just like Atom. HN isn't the audience for "big-picture" technologies
that will get more efficient over the years and have broad applications
eventually.

~~~
jamestimmins
Agreed. Given YC's "launch early and iterate" mindset, it's surprising how
little that is reflected in the HN comments for new projects.

------
jlebrech
what about using this tech to create a backup pager.

I'd love a device that ONLY does sms or text based comms (fb, whatsapp etc..)
but only the text. and nothing else.

that would sip battery.

------
jug
Time to start optimizing Android and iOS, haha...

