Alt-BEAM Archive
Message #12375
To: beam@sgiblab.sgi.com
From: "Pat Wehren" makegofar@hotmail.com
Date: Wed, 22 Mar 2000 23:02:15 PST
Subject: [alt-beam] Re: "Living Machines" question & an experiment
You're beautiful. Thank you.
>From: Bruce Robinson
>Reply-To: beam@sgiblab.sgi.com
>To: beam@sgiblab.sgi.com
>Subject: Re: "Living Machines" question & an experiment
>Date: Wed, 22 Mar 2000 17:48:45 -0800
>
>Pat Wehren wrote:
> >
> > The paper says that if the times of the neurons are roughly the
> > same, they will converge on 100100. I can't for the life of me
> > see why.
>
>Who says there's no feedback/implex? Well, I did once.
>
>OK, I decided to test out this assertion as follows. I set up and ran,
>not one, but two 6Nv loops, completely independent except for a share
>power supply (6 V battery). Decoupling caps all over the place, no
>floating inputs, everything "by the book".
>
>I first selected components that had as nearly identical values as
>possible (helps when you buy resistors and caps by the hundred). Then I
>set up indicator LED's in two lines of 6, each line driven by a separate
>Nv loop, and ran one impulse around each loop just to check that the
>timing was close for all the Nv's. I could watch the two impulses
>marching along their respective rows, and by fiddling with the phase
>shift, I was able to cross-compare the delay times for all the Nv's.
>
>Having satisfied myself that the times were, in fact, "roughly the
>same", I rearranged the LED's so each loop had them set up in two rows
>of three, with the LED's for each loop physically separate (to aid
>observation). Then I introduced two impulses into each loop in a 101000
>configuration, and let them run. The two rows of three made it easy to
>observe the pattern: in a 101000 configuration the impulses would appear
>at opposite ends of a row of three, whereas in a 100100 configuration
>they would march in lock-step down the two rows.
>
>What I found after about 6 hours was that both circuits had evolved to a
>1-0-3/4-1/4-0-0 pattern. In other words, the leading impulse would move
>ahead just a little before the trailing impulse.
>
>Twentyfour hours later, the pattern had not changed. So for the heck of
>it, without disturbing or interupting the pattern in any way, I plugged
>a low current gearmotor (10 mA) directly into one pair of adjacent Nv's
>on ONE of the loops. This completely disrupted the pattern in the
>affected loop ... it reverted back to the saturated state (101010)
>immediately. As I had not put any kind of capacitor across the motor
>leads, this almost certainly injected a lot of noise into the chip.
>
>But what was fascinating was what happened to the other loop. Mounted on
>a separate breadboard, but sharing the same power supply. In about 4
>forward-reverse cycles of the motor, the second loop shifted to a 100100
>pattern. Just like that, perfect synch, no overlapping. And it is still
>doing that, an hour later.
>
>So a noisy, low-current motor hooked directly to the Nv outputs in one
>loop affected the impulse pattern in an independent loop, with the only
>connection between them being the supply lines. Fascinating.
>
>Bruce
______________________________________________________
12376 Wed, 22 Mar 2000 23:12:25 -0800 [alt-beam] Re: Why isn't the HC4066 used for h-bridges? beam@sgiblab.sgi.com Bruce Robinson Justin wrote:
>
> Dumb question for the day:
No such thing. I hadn't seen this chip before, and it's kind of
interesting ... 4 bidirectional analog switches. Definitely something to
add to the databook.
> Why build h-bridges out of a heap of transisters and stuff instead of
> using a single HC4066 or 4016? (Quad bi-laterial switche)
Power. Like most non-driver HC chips, these can handle a maximum of 25
mA per gate. You could just as easily drive low current motors directly
of the microcore/bicore chips.
The basic h-bridge can handle 100 mA, and by substituting some higher
current transistors it can cope with 800 mA. That'd be 32 stacked chips
:)
> I haven't used a 4066 (or 4016), so I'm wondering if the current
> ratings are enough to drive a motor. If the switches don't provide
> enough current, surely stacking some chips would still be a lot
> easier than transistors?
You'd be better off using 74xx245 chips (stacked as needed). I poked
around to see if the 74HC4066 was available in a higher current family
than the HC version, but couldn't find one.
I do like this chip, though. It's very much like a low-current, solid
state relay, and I'll probably end up using it for something.
Bruce
12377 Wed, 22 Mar 2000 23:27:25 -0800 [alt-beam] Re: Exclusive club or am I being blocked? beam@corp.sgi.com Ken Hill hehe...didn't want to start a spam debate :) No one likes that!
Thanks for the input all and I'll start posting to
"beam@spindle.corp.sgi.com" as suggested instead of through the E-groups
website "alt-beam@egroups.com".
If that's not the correct address, let me (us) know.
Figured that it's easier to scan group in browser than waiting for mailbox
to fill everyday :(
BTW, Is there a "real" newsgroup location for use in a newsgroup
reader? Tried a search for alt-beam but nothing came up.
Ken
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