Alt-BEAM Archive

Message #12639



To: beam@sgiblab.sgi.com
From: Richard Piotter richfile@rconnect.com
Date: Tue, 28 Mar 2000 00:50:53 -0600
Subject: [alt-beam] Re: Sold Out, and a note on selling things on the list.


OK! I'm thinking of 2 designs. one is basicly the same function as the
Lynxmotion Quadrapod & Hexapod kits, but with a different linkage
system, and the other idea incorporates a 3rd motor on each leg that
would add more mobility. Depending on demand, and if i can actualy
produce the materials, I will then determine if and when I can do this.
I hope it works out. (the complex design would use 12 motors for a 4
legged walker and 18 for a 6 legged walker!, the simpler is 8 and 12 respectively).


David Simmons wrote:
>
> Richard,
>
> I might be interested, depending on the price. Trying to workout the
> mechanics with Kyle on some of the more difficult projects is getting
> more difficult all the time. But right now I have to put together the
> cash for a few of Dave's kits at Solarbotics.
>
> Keep me on mind if you decide to put it together.
>
> Later,
> Dave
>
> Richard Piotter wrote:
>
> > I personaly am thinking of doing a Quadrapod/Hexapod style kit in
> > limited runs. It's just an idea. I'm not sure if people would buy into
> > it, but if there was interest, I'd do them!

--


Richard Piotter The Richfiles Robotics & TI web page:
richfile@rconnect.com http://richfiles.calc.org

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12640 Mon, 27 Mar 2000 21:52:43 -0800 [alt-beam] Re: 2nd - Reverser drawing - attn. Bruce beam@corp.sgi.com Ken Hill Bruce, could you elaborate on the "fry it" part?
(or direct me to a suitable link maybe?)

The '139 use I refered to is the Z-drive in the Beam Tek's - motor
drivers paper. Mark later mentions that the ACT version works
well for this purpose but you should have a "47k pull-down resistor
for all enables and A & B inputs."

Would that be "down" to ground or just in series with the enables/inputs?

Terms like this, and positive edge, and positive logic, etc. are a
gray area here. I've been a "tech" for 20 years but never had to get
my hands (brain?) dirty till now :)

There seems too little written about the multi-chip interfacing
aspects, but plenty on the individual component designs.

Thanks for the help, Ken

>The combination of the 74HC139 and H-bridge (one chip'll drive two
>bridges) can replace the '240 reverser plus '245 driver. If you're going
>to go this route, use the complete schematic shown in the Tilden paper
>... the BEAM on-line H-bridge has positive logic and the '139 outputs
>will fry it. If you have very low current motors, you can do it all with
>just a '240 using the BEAM-online schematic.

>Bruce

>> Also, I found the circuit for the 245 H bridge and the 139
>> reverser / H bridge circuit. If I use the 139 I can eliminate
>> both the 240 reverser and the 245 H bridge, correct?
>>Ken

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