Alt-BEAM Archive

Message #09635



To: beam@sgiblab.sgi.com
From: "Leonardo Boulton F." L.Boulton@rocketmail.com
Date: Sun, 30 Jan 2000 12:46:48 -0800 (PST)
Subject: [alt-beam] Re: robot idea.




--- Evan Dudzik wrote:
> this is a case of what I call "beginner syndrome" that
> I think everyone goes thru... I know, solarollers and
> things don't seem very interesting, everyone wants to
> move right on to making walkers and the most advanced
> things they can... although it may be possible to
> make a walker as your first bot, I think that you
> should start out with simple stuff and then LEARN
> about bigger stuff, then build big stuff

Yes. I agree. I know my goal is a little high. However I'd like to
start with them, because if I can do it, then I would have made a big
step forward. So, Any idea of a basic walker?. I want to find them
online (some complete webpage), where i can go and get the whole (or
the most) info i can get... I've been to many sites, and non of them
have a complete instruction set, i mean, I've found pic's, i've found
schematics (alone), but i haven't found schematics "and" Pic's "and"
explanation of the schematics...

Thanks. I apreciate the help.


=====
mind the gap...
http://www.geocities.com/l.boulton
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9636 Sun, 30 Jan 2000 13:35:25 -0800 [alt-beam] Re: Walkers beam@sgiblab.sgi.com Bruce Robinson > Geoff Waters wrote:
>
> What is the difference between a microcore and a Bicore? They do the
> same thing, right? And could you post a schematic of the microcore.

Hi, Geoff.

A master-slave bicore and a microcore can both be used to drive a
2-motor walkers (among other things) but they behave differently. It's
interesting to compare the two just to see how the walker behaviour is
affected.

Have a look at Andrew Miller's tutorial at:

http://vsim.freeservers.com/amiller/microcore.html

Regards,

Bruce



9637 Sun, 30 Jan 2000 14:52:35 -0800 [alt-beam] Re: Bicore question beam@sgiblab.sgi.com Bruce Robinson "Phillip A. Ryals" wrote:

> ... I breadboard it, and it works fine. I solder it all
> together, and it refuses to work. I've checked all my
> solder joints, and made sure everything's touching where
> it should, but I still can't manage a working model.

Hi, Phillip:

Fast checklist:
- are you absolutely, 100% SURE that every solder joint is good?
Dave at Solarbotics reports that the vast majority of non-working
robots they repair for people are due to solder joint problems.
- is anything touching that shouldn't be? Solder accidentally
bridging a gap? Leads touching in some obscure place? I like to
run a dental pick between adjacent wires just to be sure (with
power off !!!)
- wash/clean off the soldering flux. Some fluxes are ever so slightly
conductive. When you are using resistor values in the Megohms, the
flux can sometimes make a difference.
- did you install a decoupling capacitor across your + and - supply
near the chip? Suggested value is between 0.022 and 0.1 uf. You
rarely see this mentioned in circuit diagrams.
- did you "do something" with any unused chip INPUTS? Do something
means connect them to either ground or Vcc. Unused outputs are NOT
connected to anything.
- are you using LED's to check your microcore behaviour? Are they
installed right way around?

> All I'm left with now, is perhaps that I ruined the chip with heat.
> Are the 14's more sensitive than the 240's?

No. Most chip datasheets give specifications for soldering temperature.

For both the 74HC14 and the 74HC240: "Lead temperature, 1 mm
from case for 10 seconds" = 260 degrees Celsius

Lead/Tin solder typically melts at 220 degrees Celsius, so 260 is a
typical soldering temperature.

CMOS (HC, HCT) devices are relatively sensitive to temperature -- excess
temperature causes the semiconductor metallurgy to change. However, you
would have to get the chip pretty darn hot to make it fail right off the
bat.

Using chip sockets as others have suggested is always a good idea,
especially for first time efforts. They add bulk, but it's a lot easier
to pull a chip and test it when something doesn't work.

Regards

Bruce



9638 Sat, 29 Jan 2000 18:11:33 -0500 [alt-beam] A neophyte enters the BEAM realm.... "BEAM" "William Cox" Hi Folks,
I just getting interested in this beam stuff. Solar stuff etc. has
always fascinated me, but I've been to busy with regular robotics to really
delve into it, not to mention the prices of kits I see. Personally anything
over $50 is too much for me. I MUCH prefer to do it myself. You learn a
whole bunch more. Frankly what really set me upon trying out BEAM, is the
article in Febs. Smithsonian about Mark Tilden. Fascinating. Anyway.... I
had some questions....
1. Me as a total neophyte, what do I do?? I read that a good starting place
is with a Solar Rover, BUT, it seems well ... simplistic ... a photopopper
typeish design seems so much more interesting. Yall's (Ok, you know I'm from
the South now) opinion?

2. One thing that greatly disturbs me about this whole hobby is that I can't
get everything from Rat Shack! (Sorry, I know you EEs and such are gagging
:) I'm a first class tight wad, and the thought of paying $6.00 S/H for
$2-$3 of parts is like pulling teeth, or worse! Isn't there anyway to build
a solar engine with RS parts?? Bicore? I mean, $1.00 - $3.00 is not SO bad,
but $6.00 with Solarbotics is a bit over the limit. Any thoughts?

I think that's about it. Thanks so much for your help.
-William
Snowed in in Raleigh, NC
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