Alt-BEAM Archive
Message #12433
To: beam@corp.sgi.com
From: Justin JAF60@student.canterbury.ac.nz
Date: Fri, 24 Mar 2000 19:19:24 +1200
Subject: [alt-beam] Logic puzzle - cool! Try this tougher one... :-)
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What can I say? Wow...
I followed everyone's solutions, and even breadboarded one. I made lots
of mental notes and points to discuss, but that will take a back seat
because I discovered I made a er... typo in the truth table... (doh!)
So - here is a tougher puzzle (and another chance to beat Wilf, unless
you happen to be Wilf, in which case beating Wilf might be difficult :-)
The mistake I made was in the two states that gave HIGH/Irrelevant - I
got the HIGH and Irrelevant back to front. Unfortunately, this cuts out
the super-optimisation of permanently tying one output low, making it
more difficult.
The revised puzzle is attached below.
I thought someone would be able to come up with a better solution than
me, but I was quite amazed at how _much_ simpler (and Richard thought
_his_ design could have been more elegance - ha!). As it turns out
though, my behemoth circuit finds a loophole to justify itself - those
elegant solutions were solving a simpler puzzle. If you guys are still
enthusiastic though, I suspect (and hope) it will be put to shame once
more :-) If enthusiasm has waned, or it's too tough , I guess I'll
have to use an XOR chip.
If you're interested in what this bizarre gate is for, it's like this:
A motor controlling an extra leg articulation needs to be turned on and
off, and have its direction controlled by from specific combinations of
the two switches. The outputs go to separate 240 enable pins, one bank
of inverters acts as motor drivers (thus this output controls when the
motor is on) and the other bank acts as a reverser, switching the signal
before it enters the drivers, thus controlling the direction the motor
turns. Both input switches are normally closed. The motor should turn in
the direction of an open switch, thus it should stop turning when both
or neither switch is open. There might be a much easier way to do this,
as I haven't been getting much sleep... :-)
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12434 Fri, 24 Mar 2000 09:14:08 +0100 [alt-beam] Re: Cricket "Thomas Pilgaard" I'd like it aswell.
- Thomas
>
> Me too...
>
> Timothy...
>
> >
> >That sounds pretty cool. Could you send me the schematic?
> >
> >Rusty Jones
> >
> >email- toby503@aol.com
>
> ______________________________________________________
>
12435 Fri, 24 Mar 2000 09:14:10 +0100 [alt-beam] Re: 1381 DLSE "Thomas Pilgaard" I'm building a beam-ant from the excellent ucoba schematics right now.
I've had no luck with the 1381DLSE - I never had it do anything, so I
settled for the PM1 SE, which should be just as efficient. plus the
component-count is a bit lower than the DLSE.
If you've got a 1F gold cap rated at 2.5v please mind that you may get in
trouble with the 1381L. In ref. to an earlier thread on this subject the
diode (of the PM1) adds about .7v to the triggervalue of the 1381.
The trouble is, the cap could leak more current than it would recieve when
overcharged, which means that it probably would never hit the triggerpoint.
I've had no luck in using a 1381J and a 3733 Sunceram with a 1F goldcap so
I'll go for a 1381C which I gotta order first thing when my paycheck
arrives.
Cheers,
Thomas
> So, i've been looking to power my unicore circuit with this, i've
> got this
> and a ALS245 motor drive to plug this sucka into. Now, 1 farad
> cap and a 1381
> L CMOS, what kinda power out am i gonna get from this, i got this off of
>
> http://www.geocities.com/ResearchTriangle/Node/3904/pictures/ucoba.html
>
> does anybody have any experience whatsoever on this circut? ThAnKs!
>
> -Spencer
>
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