Subject:
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Re: Binary Pneumatic addition with two pistons
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Newsgroups:
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lugnet.technic, lugnet.robotics
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Date:
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Mon, 9 Jun 2003 19:29:16 GMT
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Viewed:
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1516 times
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In lugnet.technic, Mark Tarrabain wrote:
> Kevin L. Clague wrote:
> > In my continued quest to develop pneumatic computing capabilities (what can I
> > say, I'm a geek), I created a combination AND and exclusive or (XOR) gate using
> > two pistons and five switches. This combination lets me add to bits using just
> > two pistons, 1/3 of the pistons used by me previously.
>
> Hey Kevin. Big fan here.
Hi Mark,
>
> I'm not sure if anyone has ever observed this before, but if one is only
> ever wants the pneumatic switch to be at one of the two extreme ends, it
> appears as if the LEGO pneumatic switches behave exactly like electrical
> SPDT relays. Since Kevin seems keen on making logic gates from
> pneumatics, it got me thinking... and I know it's possible to make
> Two-Input AND, NAND, OR, and NOR gates from 2 relays, and a Two-Input
> XOR gate from 4 relays if no floating output state is desired, or 2
> relays for the XOR gate if one wants one of the output states to be
> floating. Has anyone else ever tried doing mappings like this to see
> how well they work in practice? I realize that if no floating states
> are desired for pneumatics, one would need both a positive and negative
> air pressure supply, but that shoudln't be too difficult, should it?
I've maded two pneumatic adding machines (http://www.users.qwest.net) and I can
attest that it works quite well.
With LEGO Pneumatics, the pistons are double acting. They have a port to make
them expand as well as port to make them contract. This is an alternate
solution to your positive and negative pressure, right?
The pneumatic switches can be in one of three states:
pressure on left port, release of pressure on the right port
pressure off on left port, pressure off on right port
release of pressure on the left port, pressure on the right port.
My pneumatic logic gates always provide pressure and release, they don't put the
output switch into off state.
I can make AND and OR using two gates and one switch, and XOR with two gates and
5 switches. I can also make a two input two output multiplexer with four
switches. The NOT function can be achieved for free just by swappping the hoses
at a piston's input ports.
A single large piston with a single switch act as a memory, due to the fact that
when no outside force acts upon them (pressure at inlet ports or weight), they
do not change shape.
I've figured out how to make J/K flip flops also.
>
> With enough pneumatics, one could even build an entire air-powered computer!
I've been working my way there. I've got all the computing elements that I
need, except RAM, which would be too expensive to model using pneumatic memory
cells.
I'm going to try to make memory cards out of technic beams with pins stuck in
the holes for ones, no pin means zero. This could be a very difficult thing to
build though.
I looked up some information on the first microprocessor, the 4004. It was a
four bit processor that took 1000 transistors to make. Something on that scale
might be doable.
>
> Geeze, I wish I had the pneumatic components to try some of the stuff
> I've seen here out.
Try bricklink.com
>
> > > Mark
Kevin
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