
Tin Can Phone Modem - todsacerdoti
https://www.mikekohn.net/micro/tin_can_phone_modem.php
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razakel
Tangentially, a UK ISP managed to get DSL to work over wet string:

[https://www.revk.uk/2017/12/its-official-adsl-works-over-
wet...](https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-
string.html)

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EvanAnderson
Reminds me of gigabit Ethernet over rusty barbed wire:
[https://news.ycombinator.com/item?id=15910263](https://news.ycombinator.com/item?id=15910263)

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dfox
One thing of note is that 1000-base-T and G.991 (marketed as SHDSL/HDSL/SDSL
depending on country/telco) is somewhat similar technology that is hard to
classify as being baseband or broadband. One of my somewhat more absurd
networking experiences was using SHDSL as “LAN with cheap wire” on anime
convention. We had few hundred meters of flat phone “tinsel wire” left over
from previous project and I had somehow acquired bunch of Cisco 17xxs and
WIC-1SHDSL line cards. It worked well enough for our purposes and I learned
one thing: plain G.991 works over random wire reasonably, while G.991bis with
enabled channel bonding does not (probably because of crosstalk).

Edit: one notable thing was that we tested the whole setup beforehand with
same cables, but coiled. And all the links were capable of at least 3Mbps.
Once we unraveled the cables on the site most of the links were unable to
train at more than 512kbps in two-pair mode, but worked reliably at 1.5Mbps in
single-pair mode.

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taneq
This reminds me of an old magazine article (Acorn User?) that described how to
use a pair of BBC Micros with wired in LDRs and flashlights to transmit data
wirelessly.

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afandian
And that reminded me of a childhood project where I hooked the user port (8
bit parallel) of one BBC up to another and wrote a chat program that sent data
from one machine to another by POKEing ASCII values IIRC. Not a million miles
from what you could do with an IBM PC printer port.

Not much use, the cable was about a foot long.

My child's generation won't be able to do that, but I'm glad we have arduinos
and ESP32s to fill the same niche.

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Nybercanjo
netcat on a lan can do it for kids today

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afandian
it's less exciting just plugging an ethernet cable in

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ape4
Very fun. Now for the next step, replace the cans with quantum entangled
objects ;)

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aspenmayer
I don't know much about entangled particles or objects; that being said, the
one thing I keep hearing is that quantum decoherence cannot violate causality
or allow communication faster-than-light. Not that you were saying that, but I
keep hearing that people think a kind of quantum walkie-talkie or one-time-pad
is possible. I honestly don't know either way, as I'm not in this field.

It certainly is interesting, though!

[https://sci-hub.tw/https://doi.org/10.1038/nphoton.2007.22](https://sci-
hub.tw/https://doi.org/10.1038/nphoton.2007.22)

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behnamoh
I don't know why this hasn't been upvoted much so far. It's literally the
definition of hacking (da, Hackernews). I'm always hesitant to use "literally"
where it means figuratively, but this can modem literally _is_ hacking.

And to think that the concept is so simple and yet, so much fun, makes it yet
more interesting.

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TedDoesntTalk
What do you think is the maximum transmit distance with error correction bits?
Obviously it would be affected by string tension and string material, but do
you think it would work strung between two nextdoor neighbors child bedrooms?

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dfox
If you assume some kind of error correction the question stops being “would it
work” and instead becomes “how slow/fast would it be”

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tartoran
We used to string talk back when we were kids, we built a poorman's network of
those in my neighborhood and worked well until the next storm took them down.
It is very rewarding to actually experience first hand how the vibration turns
in to sinewaves and back into vibration. The problem with the current
generation of kids is that most of their playtime is digitized, which may have
some advantages but also I see quite a few disadvantages. Well, I don't want
to take the conversation in different direction, this is about hacking modems
over wire and is pretty cool project.

