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Subject: 
Re: Brickfest Pneumatic Master and new Pneumatic Gate Circuits
Newsgroups: 
lugnet.technic
Date: 
Mon, 29 Aug 2005 17:14:17 GMT
Viewed: 
9962 times
  
In lugnet.technic, Mark Bellis wrote:

[SNIP]


> I've done some more study in order to investigate the 3-input gate, using the
> 4-switch module in multiple.  This has shown me how the original 4-switch module
> from your sketch is an AND gate in its own right, as long as the differential
> pressure input is one input and the switch position is the other input.  A
> reverser between stages can invert the differential pressure input, making
> endless possibilities for the logic function of the system, by allowing the
> output to be high in 1, 3, 5, or 7 of the eight combinations of three inputs.

The design process here was very simple:

  Mark Tarrabain's wonderfully simple single switch AND gate does not produce
differential pressure.  What do I have to add to this gate to get the other
phase of differential pressure?

  The result is adding three switches.

  I then asked myself "what does it take to make a single pressure OR gate?".
This took 3 switches.  I enhanced to differntial pressure by adding one more
switch.

> 
> Seeing the 4-switch module that way, and using it in multiple, makes for a gate
> without any extra propagation delays due to daisy-chaining.  It's also more
> cost-effective, since only four switches are required.  For a gate with two
> switch position inputs (rather than one switch position and one differential
> pressure), one of the switches driven by "A" can be trimmed from my diagram,
> making a 1+4++4 gate.

Yes, hooking Mark's single switch AND gates in series comprises a multi-input
AND gate.  This is fabulous for making sequencers, because you minimize the time
and the part count.

> 
> I still like the elegance of my 3+3 design, especially because it's symmetrical,
> but the most elegant solution is rarely the sleekest!  In pneumatics there is
> more to be said for reducing parts count because the parts are so expensive.
> That's where 1+4++4 scores over 3+3++4.
> 
> Overall this means that a set of combinational logic can be achieved with
> 4-switch AND modules and 4-switch reversers such that there is only a single
> propagation delay between states, which is good for machines whose timing is
> critical, such as your walkers.

Yes, it makes the slow walkers not as slow :^)  But like I said, I stick to the
single switch AND gates for my walkers.

> 
> Mark

Kevin



Message is in Reply To:
  Re: Brickfest Pneumatic Master and new Pneumatic Gate Circuits
 
(...) Yes, I can see how the 2-cylinder design is more cost-effective, particularly since a Backhoe has 10 cylinders and only 7 switches. That allows more cylinders to be used for AND and OR gates, saving the switches for XOR gates. I've done some (...) (21 years ago, 28-Aug-05, to lugnet.technic)

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