
Logic Gates as Pulley Systems [video] - vinchuco
http://vimeo.com/93042377
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baddox
That's a cool implementation. It reminds me of domino logic gates:
[https://www.youtube.com/watch?v=SudixyugiX4](https://www.youtube.com/watch?v=SudixyugiX4).

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chas
This is incredible! After hearing about the MIT tinker toy optimal tic-tac-toe
machine[1], I built a half-adder out of dominoes[2] around the same time
period as that video and hadn't ever heard of anyone else messing with the
concept.

[1]
[http://museum.mit.edu/nom150/entries/1215](http://museum.mit.edu/nom150/entries/1215)
[2] [http://imgur.com/a/qq7Kl](http://imgur.com/a/qq7Kl)

~~~
hedgehog
I was curious about other mechanical digital logic projects and this stood out
in the reading:

[http://www.elazary.com/index.php?view=article&id=46](http://www.elazary.com/index.php?view=article&id=46)

The rest of the blog is pretty interesting too.

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shagie
This reminds me of an article written for the April (first) edition of
Scientific American many years ago... 1988.

The key thing to look for is the word 'Apraphul' which is the name of the
island this was 'discovered' in. The part of the text of the article can be
seen at Google Books [1] (many of the articles are behind a paywall)... though
finely digging enough, I found it in a forum with part of the article [2].
Still, searching on 'Apraphul Pully' can take you to a number of other
interesting pages (including one discussing the article's system).

[1]
[http://books.google.com/books?id=0Rb5jBg6sJwC&pg=PA117&lpg=P...](http://books.google.com/books?id=0Rb5jBg6sJwC&pg=PA117&lpg=PA117&dq=Apraphul&source=bl&ots=UIPD1t3jff&sig=gKTprj2YA8TcF_WpRu6G30QvJlA&hl=en&sa=X&ei=F1SJU_fpDIONyATyoYK4DQ&ved=0CC0Q6AEwAA#v=onepage&q=Apraphul&f=false)

[2]
[http://s10.zetaboards.com/The_New_Coffee_Room/topic/7132776/...](http://s10.zetaboards.com/The_New_Coffee_Room/topic/7132776/1/)

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lalos
Fun fact, if you can build a NAND gate or a NOR gate, you can derive all other
functions. This is called functional completeness.

~~~
vampirebat
And you have to be able to compose gates.

Not to detract from a very cool demonstration, but it appears that all of the
energy comes from the "inputs" which have to overcome all of the frictional
forces in the system. With semiconductor gates, each gate provide the energy
required to drive the gates it is connected to which facilitates composition.

~~~
GauntletWizard
Yes, this system is also prone to 'fuzzy' states due do slight variances that
would multiply quite a bit if used for a full computation. It'd be cool to see
a rectifier for this system, which will guarantee a full 1 or 0 state given a
marginal state, though I'm not entirely certain how you'd build one.

~~~
bigiain
Mechanical engineers have been solving that problem in various ways for
hundreds of years. The gate in a film projector(or camera), the steam valve
block on many steam engines, even the gear selector drum assembly on a
motorcycle gearbox - and the mechanical gubbins inside every lightswitch
displays the sort of hysteresis you need. I bet a typical 1950's engineer
would solve that problem for you in a dozen ways in 20 minutes. (these days I
suspect many engineers today would reach for a microcontroller and a
servomotor or solenoid...)

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aetherspawn
Extremely impressive. Almost tempting enough to try and build an adder, but I
fear for anything larger than a few gates the concept starts to become clunky
to implement (see the gates at the end of the video ..)

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michaelmior
I was just wondering how long it would take someone to build an adder. I
wouldn't be surprised if someone went for it.

~~~
aetherspawn
Adders are curiously simple! You just need a clock, otherwise they kind of
break. How you clock weights ... hnng, no ideas there.

~~~
qbrass
Pendulum clock. [http://electronics.howstuffworks.com/gadgets/clocks-
watches/...](http://electronics.howstuffworks.com/gadgets/clocks-
watches/clock4.htm) Was the best illustration of a simple one.

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saint-loup
To file in the list of unconventional computing
[http://en.wikipedia.org/wiki/Unconventional_computing](http://en.wikipedia.org/wiki/Unconventional_computing)

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duncanawoods
Nice. It made me think of this piece of art by Michael Craig-Martin. A
confounding pulley system:

[https://www.youtube.com/watch?v=9yQdFX7BgzA#t=354](https://www.youtube.com/watch?v=9yQdFX7BgzA#t=354)

edit: btw I can recommend every engineer watches this BBC series "what do
artists do all day". The thinking processes of artists share a lot more with
engineering that I expected and I found all episodes absolutely fascinating.

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sudhirj
Obligatory XKCD: [https://xkcd.com/505/](https://xkcd.com/505/)

