Subject:
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Re: New 3-Input Multi-function Pneumatic Logic Gate
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 6 Sep 2005 22:05:41 GMT
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Viewed:
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3739 times
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In lugnet.technic, Kevin L. Clague wrote:
> In lugnet.technic, Mark Bellis wrote:
> > Here's my latest pneumatic logic gate with differential inputs and outputs.
> >
> > This one has 4-switch reversers to make it configurable for almost any
> > combination of inputs. Replace the reversers with permanently swapped hoses
> > when you have the function you want.
> >
> > It uses two of Kevin's 4-switch AND modules.
> >
> > You can make the output go high in 1, 3, 5 or 7 of the eight combinations of
> > inputs A, B and C. A table shows which combinations of reverser settings do
> > what.
> >
> > http://www.brickshelf.com/gallery/mbellis/Technic/Pneumatics/Building-Blocks/pneumatic_3_input_multi_function_gate_circuit.jpg
> >
> > PLMKWYT
> >
> > Mark
>
> Mark,
>
> Aren't Reversor R1 and Reversor R4 redundant? R1 can reverse the A input,
> which drives a piston which controls a switch, who's output is reversed by R4.
> I see no reason for the piston and switch between R1 and R4, unless you are just
> showing that something has to be feeding the rest of the circuit.
>
> The differential pair coming out of R4 are merely delayed versions of A or
> inverted A, right? There is no real computing happening there.
>
> Kev
Yes, R1 and R4 are redundant as shown in the table notes :-)
The idea was to start with A, B and C all being either differential inputs or
switch positions. The use of a switch for A means that its input is buffered to
the gate output, otherwise the output cylinder takes pressure direct from A and
that might have an effect upstream (like another load-bearing cylinder losing
pressure when the output of this gate changes). If you're not driving anything
that's load bearing, you can eliminate R1 (use R4 instead) and the switch for A,
and feed A's differential pressure directly into R4.
Using buffered A means that the propagation delays are more comparable between
A, B and C, though A should be loaded with another switch for more exact
equality (a load of 2 switches per cylinder).
BTW Have you found any problems with new cylinders not pulling very well when
contracting? I was trying this rail point actuation scheme (by Jon Reynolds)
and found that the top of the cylinder leaked enough to require 11 pumps of a
hand pump to move it, whereas it expands within 1 press of the pump:
http://www.brickshelf.com/gallery/mbellis/Trains/Others-Models/GWLTS3/jons_pneu_points_1_gwlts3.jpg
http://www.brickshelf.com/gallery/mbellis/Trains/Others-Models/GWLTS3/jons_pneu_points_2_gwlts3.jpg
Mark
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Message is in Reply To:
 | | Re: New 3-Input Multi-function Pneumatic Logic Gate
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| (...) Mark, Aren't Reversor R1 and Reversor R4 redundant? R1 can reverse the A input, which drives a piston which controls a switch, who's output is reversed by R4. I see no reason for the piston and switch between R1 and R4, unless you are just (...) (19 years ago, 6-Sep-05, to lugnet.technic)
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