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Geek Culture / Mechanical AND Gate Made of Strings

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Dark Java Dude 64
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Posted: 7th Jun 2013 09:11 Edited at: 7th Jun 2013 11:27
Hi all! Over the past few weeks I have been creating a design for a mechanical logic gate based upon strings. Today I have a working prototype that I'd like to show you!



This is what I was working on when I posted my Interesting Math Question thread. In the upcoming future I plan to build more complex stuff out of these gates to hopefully produce some pretty awesome stuff.

What's the point of all this? Fun! No practical purpose here, but why not?

Please feel free to give me feedback if you'd like!
Libervurto
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Posted: 7th Jun 2013 18:01
You should've pulled the right one down at the end, for all we know it's not connected. Interesting though, I'd like to see what's happening on the back side.

The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Dark Java Dude 64
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Posted: 7th Jun 2013 23:06
Ah yes I would have, guess I didn't. Interestingly, all of the action occurs on the front, near the top there is a small bit of fishing line that is crucial to the operation of the gate but you can't see it on camera. Perhaps later I'll do another video describing how it works!
Libervurto
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Posted: 8th Jun 2013 01:57 Edited at: 8th Jun 2013 07:36
Is this roughly how it works?
[removed old image]

So there's enough slack for either to go up on its own, but if both go up they pull up the ring.

Could you make an adding machine out of string? That would be pretty cool.

[edit] No wait, mine wont go down again until both inputs are down. You must have done something different.

The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Dark Java Dude 64
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Posted: 8th Jun 2013 02:41
You are very close! That bit of fishing line I shall refer to as the loop. As far as the output goes, that's pretty close except I have a separate string attaching that slider and the output; it tensions up when one input is raised and therefore actually pulls the output high when both inputs are raised. The ends of the loop are actually anchored to the substrate (the board) and the inputs attach to it by sliders instead of a knot. The reason for that is to ensure that the center slider travels the same distance as the inputs move, if it was attached as in your image it would only move half the distance. Basically it adds the distance of the two inputs. If neither input is raised, the center slider isn't, if one of the inputs are raised, the center slider is raised one unit, and if both inputs are raised, the center slider is raised two units. The raiser is the string that attaches the output and the center loop, it's one unit long and therefore only pulls the output high when appropriate.

Then watching the video it should be somewhat obvious how the output is lowered again. I call those the droppers.

But good job for guessing so closely!
Libervurto
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Posted: 8th Jun 2013 04:42 Edited at: 8th Jun 2013 04:43
Not sure I quite followed that. Like this?

We need to invent string logic notation.

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Dark Java Dude 64
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Posted: 8th Jun 2013 04:50 Edited at: 8th Jun 2013 04:50
You're getting closer! Hell, I'll just create a drawing for ya:

I offset the output a tad to show that 'raiser' string. The ends of the fishing line which I beautifully free handed are anchored.

Libervurto
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Posted: 8th Jun 2013 05:32 Edited at: 8th Jun 2013 07:12
How's this?


Inkscape is a lot of fun to mess around in.
A neat thing about this is that upside down it's an OR gate.

[edit]
I just realised the middle dot in the 111 (top right) diagram should be higher and the lines to it should be tight. Or maybe all three "dropper" dots should be at the same level with tight lines.

The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Libervurto
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Posted: 8th Jun 2013 07:24 Edited at: 8th Jun 2013 07:38
I think I've figured out a NOT gate:


Not really a gate but here's equivalence:

Useful for sending values across.

The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Dark Java Dude 64
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Posted: 8th Jun 2013 07:33
Those images look pretty good! And that's right, upside down it is an OR gate! In that scenario, it's behaving like an AND gate with both inputs and the output negated. One thing I haven't mentioned yet, each bit is transferred by two strings instead of one. For example, each input and output on my gate has two holes that it goes through to the backside with; the string that continues beyond those holes serves as one of the two strings that transfers the bit. Basically, one pulled is a logical high and the other pulled is a logical low. Technically they are they same string as they go through the logic gate as a single unit. But this means that a not gate isn't even necessary per se, simply connecting the gates correctly constitutes a NOT gate. If that doesn't make much sense, all is cool as I'm just about to make a video that will explain stuff and demonstrate this half adder the I'm just about done building at the moment.
Libervurto
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Posted: 8th Jun 2013 07:48 Edited at: 8th Jun 2013 07:49
Would my equivalence actually work, or would the middle string just slope? I feel like if it was tight it would work but maybe it would be hard to get it tight enough and might even cause some resistance. I'm guessing the friction would build up pretty quickly if you added multiple gates together. Will probably need some pulley wheels or something to reduce friction.


The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Dark Java Dude 64
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Posted: 8th Jun 2013 08:13
I am beginning to realize that... They aren't so much of an option however...

Lol I just rage quit on that half adder. Got all the gates done but connecting them made me lose it. I shall go back and finish it soon, hopefully tonight!

That said, am I sane to want to build a computer with these? :/
Libervurto
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Posted: 8th Jun 2013 08:29
Quote: "am I sane to want to build a computer with these?"

I'm the guy who made up his own number system so I don't think I'm qualified to comment.

Do you have any chicken wire? That would make a pretty good "breadboard" for this, and the metal might reduce friction.

The difficulty in learning is not acquiring new knowledge but relinquishing the old.
Dark Java Dude 64
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Posted: 8th Jun 2013 09:03 Edited at: 8th Jun 2013 10:25
That is a good idea! Well, originally I started out using all regular string, the loop was as well. I then switched to entirely fishing line which worked great as far as friction goes but the fishing line was pretty much impossible to work with for something like this which requires so much precision. Then I had the idea of using line only where I needed it, the loop, and everywhere else I used string. That is what I'm currently doing and it works nicely. The real friction issue I have now is just with the string and the cardboard as it goes through those holes, so I'm thinking of managing that by maybe lining the cardboard holes with plastic wrap or foil and maybe even oil it up a bit. The chicken wire is certainly a great idea, it would probably work a treat.

For now I'm going to put off my half adder until tomorrow maybe, but I'll likely record a video explaining the workings of the gate and such in a few minutes here.

Edit: Aye, I'm finding it quite tough to verbally explain how my logic gate works with the diagram, I suppose I'll let people continue to be in mystery until more ask how it works.
Indicium
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Posted: 8th Jun 2013 20:16
Completely off-topic - sorry, but Obese - how do you create your drawings? They're consistently fantastic.


They see me coding, they hating. http://indi-indicium.blogspot.co.uk/
Libervurto
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Posted: 9th Jun 2013 00:32 Edited at: 9th Jun 2013 00:36
@Indicium - Gee thanks. I use Inkscape, which is a vector drawing program. It's very simple to make nice looking things with it because it's so easy to tweak everything since it's all vectors. It's free to download too!

The difficulty in learning is not acquiring new knowledge but relinquishing the old.

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