Alt-BEAM Archive

Message #05973



To: beam@corp.sgi.com
From: "Jason -" evenflow88@hotmail.com
Date: Sun, 05 Sep 1999 13:25:53 GMT
Subject: [alt-beam] Beam chat


Hie i would again like to host a chat at the yahoo club at the 6th of
september 1999 at 4.ooPM mountain standard time...see you guys there
again....the topic is mobile robots with beamish brains..thanks

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5974 Mon, 06 Sep 1999 02:13:04 +1200 [alt-beam] Wilf Rigter's solar power smart "head" beam@corp.sgi.com Justin Hiya,
I'm attempting to build the impressive head at
http://home.pacbell.net/wundoba/psh.html
and I have a few questions regarding it and bicore heads in general.
I sent email to Wilf, but haven't got a reply, so I was wondering if
anyone here had any thoughts on the following points.
I have never built a head before so first things first:

Do you use a gear motor? If so, what kind of ratio is the "Escap 16 DC
motor" mentioned (or a suitable ratio in general)?

Would I be correct in believing that motor drivers (not shown in the
diagram) are needed for this circuit?

The resistor values on the bicore seem potentially odd - would these
have been determined by adjustment pots, tweaked, then replaced with
matching resistors? (ie should I expect to have to adjust mine, or are
the given values likely to fine for all?)

Also, I don't quite grok the 6.2M vs 10M difference between resistors in
the bicore. Is this because that's what the hypthetical pots turned up,
or is there a reason for it that I'm missing?

Can anyone me a rough idea what the LDR's should be like - I'm using
cheap ones, and since I don't know what sort should be used, I don't
know if they're suitable.

If there is advantage or necessity to use good LDR's, what constitutes
good? Specs for ones I'm using are as follows:
Dark resistance {ie pitch black} >10 Mohm.
At 10 Lux - 48-140 k ohm
Resistance vs illuminations is R = AL^-0.85
where R is ohms, L is Lux, and A is constant "340-991 x 10^3"
(which doesn't look all that constant to me... :)

(I've got it up and doing stuff, but not particually directional stuff.
It's an annoying behaviour that could be any of several things, from too
much inertia acting on an ungeared motor, to cheap LDR's that don't make
the grade. I'm fairly sure I know how to fix it, but as it involves some
changes that would difficult to reverse, I'm asking first in the hoe of
having my suspicions confirmed before I act...)

Thanks for any help
Seeya
Justin



5975 Sat, 04 Sep 1999 22:37:34 -0700 [alt-beam] Re: tech am beam@sgiblab.sgi.com Senior Bumper314@aol.com wrote:
>
> Did you all hear that radio shack is now being stocked by Tech america, so
> now hopefully they will have good parts =)
>
> steve

Praise those darned people! No more "I went to rat shack but only found
'npn style transistors'"
Evil grin


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