Boolean logic gates using rotations

[randomwraith]

Hi All,

Mechanical computations has always been an interest of mine and a long time ago under the pseudonym "The goldfish Online" I posted (on Lugnet) details of some mechanical logic gates using push/pull mechanisms (see http://goldfish.ikaruga.co.uk/logic.html - sorry I'm too new to post urls) that I had constructed using my Technic collection. These suffered from a variety of problems, such as intertia & signal decay, but they demonstrated a principle well enough, which was the aim.

Well, now it's along time later, I've changed my online identity and have been busy building. I know many people have been pondering such devices on forums, but I've not seen anything beyond a NOT gate. This surprises me a little given that it seems to be fairly well known that one can add or subtract axle rotations using the differential gears.

By using additions an subtractions rotations I've been able to construct a selection of the most simple boolean logic gates. I take a stationary axle as a logical 0 and a rotating axle as a logical 1. Obviously one has to take care to ensure logical 1s are rotating at the same rate or the addition and subtraction mechanisms, which are key to the gates, will misbehave, but that's fairly easy to ensure.

The logic gates that I've constructed so far are:

A NOT Gate, which includes a power source for the rotations (see http://goldfish.ikaruga.co.uk/rotnot.html );

An XOR Gate (see http://goldfish.ikaruga.co.uk/rotxor.html );

The AND Gate (see http://goldfish.ikaruga.co.uk/rotand.html );

An OR Gate (see http://goldfish.ikaruga.co.uk/rotor.html );

The Half adder (see http://goldfish.ikaruga.co.uk/rotha.html ).

Each page has a video of the gate in action, complete with a cheesy text-speech commentary! And if you're interested details the algebra required to achieve the given logic function are provided.

I've also posted details for the addition, subtraction and absolute value or one-way gearing mechanisms (see http://goldfish.ikaruga.co.uk/rotmaths.html ) that underly the logic gates - you may have seem similar devices posted elsewhere.

In principle, it should be possible to create any number of gates, especially the more complicated full adders, flip-flops etc, but I have a feeling that intertial issues, propagation delays, gear slippages and all the other usual problems associated with things mechanical will come and haunt the roost.

Feel free to contact me with any comments.

Enjoy,

RW.

Edited May 24, 2012 by randomwraith

[lightningtiger]

I don't normally visit this forum, but the magic word 'Boolean' made me visit.....you links don't work.

Oh, by the way....no NAND gate ?

Edited May 23, 2012 by lightningtiger

[Blakbird]

I don't normally visit this forum, but the magic word 'Boolean' made me visit.....you links don't work.

The links can be fixed by removing the ); from the end.

[lightningtiger]

Interesting designs, the NOT gate is actually a NOR gate with an input tied high.

Excellent work 'randomwraith'.

[randomwraith]

Thanks for the comments. I've fixed up the links - well spotted. Note they need the http:// in front of them in case your browser drops it.

re: NAND gate. Well these are the gates I've built so far :-) Everything is there to build one. Actually, I have made one whilst trying, unsuccessfully, to build latch.

re: NOT gate as NOR with inputs tied low, I think, or and XOR with the inputs tied high. But, yeah, the principle is the same. The nice thing about NOTing any of the gates is that it introduces a power source so any output 1s are being freshly driven.

Cheers,

RW

Try the links now ...

RW

Edited May 24, 2012 by randomwraith

[JopieK]

Boolean logic is always nice (although my high school students probably won't agree ;)) Nice job! Creating a NOT is of course quite a challenge.

[jasonsmith]

What a fantastic idea, job well done.