### Where is it?

The K'NEX Calculator is now located in the Olin College library. If you are interested in a demo, feel free to visit!

Grant Hutchins said...

Great to hear!

Dan said...

I discovered the phenomenon of mechanical logic gates a few years ago and have been looking for anyone who has done anything with it. This and two others are the only ones I found that implement at least a 4-bit adder; this does the most by far though.

I have been toying with this idea myself, and I have worked out some designs as best I could using moving rods to represent bits. I have thought about it a lot and I think I have a good design, or that I am at least getting somewhere with it. This is the first place that I see a possibility for my effort to be worth anything, so I would love to show you what I have thought up.

If you could PLEASE email me at DanCook1021@aol.com then I could send a picture that I sketched out in paint and do my best to explain it. DanCook1021 is also my AIM account, so I can recieve IM's as well.

Most of this is based off of the fact that an "OR" can be simulated by a set of rods pushing up against a common plate which pushes out another rod, and that a "NOT" can be simulated using a cog or lever. The issue this initially presents is that it relies on a constant force (gravity, or a rubber-band if you want to use different orientations) to keep an "OR" at zero/false when no force is present. When adding "NOTS" and chaining gates together, you end up with a bunch of resisting forces, and you need more & more counter force. HOWEVER, I have designed a "buffer" where an output is affected by an input, but the input is not affected by the output. This involves a couple of cogs, one which must be continuosly turning; the input moves a third cog into place to connect the 2 cogs, and in turn, move the output rod up until it loses contact with the cog and just "floats" at the top. When the input is released, the output falls back into place because the cog holding it up becomes free again. To make sure that a momentary input ("edge") creates at least a momentary output, a device holds the connecting piece in place until the output is fully extended. This buffer will not need to be used in every single connection, just where it is necessary. This buffer ALSO allow for feedback, as the output is slightly delayed from the input. Buffers placed side-by-side will allow a single axle to power them all. Combing nots and ors provide the other gates, though I do have a design for an XOR gate which is difficult to describe without a picture. All of these seem suitable for lego-technic, though K'NEX is also feesible.