Alt-BEAM Archive
Message #13811
To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@telus.net
Date: Fri, 21 Apr 2000 16:50:18 -0700
Subject: Re: My Poor Walker (Its kicking its legs around like awild....)
Bernard Nazari wrote:
>
> Wilf,
> So would your multi diode PNC work or should I use something like
> Bruce's PNC ...
I'll be the first to say it ... if you have a 4 Nv loop, use Wilf's
circuit. I do.
Mine's better suited to big loops, branching networks, etc.
Bruce
13812 Fri, 21 Apr 2000 21:27:54 -0400 (EDT) Galvanic Action to power BEAM devices beam@sgiblab.sgi.com Jeffrey D Spears
Greetings;
I am curious if anybody has fooled around with galvanic action between
dissimilar metals in BEAM applications.
Thinking about the subject outloud, I imagine potential difference
from galvanic reactions comes in the form of an E-field between the
two metals across the electrolyte--similar to solar cells. No doubt
the potential developed is pretty small---perhaps millivolts. However,
if the E-field acts as above, then individual *cells* in series would
sum.
For example, lets fix our design for use in saltwater. A battery
of cells could have a printed circuit board etched with little
rectangular pieces linked in an alternating series type format. One
cell would be left copper clad, the one next to it would have zinc
plating. The board will end up looking like a checkerboard. The space
between adjacent pads would have to be optimized for performance.
I do not know if it is possible to plate zinc onto copper, but lets
just assume we can. Ok, we take two of these boards and have it so
when we put the boards together with a little gap in between, each
copper pad on one board mates with a zinc pad on the other. In
operation the thing would have saltwater flowing between these two
plates.
Lets say five millivolts per cell. Then 100 cells, a ten by ten
matrix, would provide half a volt. Its funny how when fooling around
with BEAM stuff, we think of the flow of charge as opposed to
current eh? Well, imagine in the case of the above cell, current
could definitly be tought of as the amount of charges flowing past
a particular point! :-)
I think Galvin built a similiar arrangement, but instead of salt
water---he used frog guts (eeeww!) :-).
The series arrangment of the individual cells of this battery will
cause the voltages to sum. The individual batteries could be series'd
or paralleled to the BEAM designers taste.
To be sure--Im talking potato clock technology here! :-)
One downside to this arrangment is lifespan--which must be finite
as the copper and zinc pads deplete over time. In fact, imagine the
metal thicknesses could be proportioned to deplete at the same time.
I worked for the US Coast Guard for ten years up in the radio
room at various land and sea billets. Although I did not work with
them directly, was exposed to buoys, which the Coast Guard maintains
tens of thousands of. The lights on buoys are all powered by lead
acid batteries. Buoys must be maintained constantly. There are on
the spot fixes when they go out, and annual maintanance. Recharging
and replacing batteries is very expensive in materials, boats and
people. IF the Coast Guard could replace the lead acid batteries
with some sort of salt-water battery, THEN they would have. I am
willing to bet they TRIED. The reason I say all this is that the
idea outlined above probably isn't practical.
On the other hand, the same experience brought me into contact with
NOAA data gathering techniques. On the IceBreaker I worked on, there
was installed a salinity monitoring outfit. This was NOAA equipment.
It had a little launching tube mounted to one of the handrails near
the edge of the ship. The sensor was a torpedo shaped job, heavy
lead on the nose, plastic tail section--shaped like a torpedo. The
nose had a small sensor and the body had a spool of very fine
copper wire. To operate the thing, they would take a little torpedo,
hook the end of the copper wire to a terminal on some box, stick
the thing in the tube and drop it. The little torpedo would provide
signals up that one wire (and perhaps the hull of the ship) to the
box that would radio the signals to NOAA via GOES satellite.
If the reader is still awake, then perhaps this may pertain to the
subject as well.
I recall reading an article in Scientific American regarding an
autonomous ocean transfersing probe. Here is a sysnopsis of the
opertion: The thing is shaped like a long tube. Think 2 meters
long, 2 decimeters wide. This tube has control surface, rudder,
dorsals etc. When on the ocean surface, it has a density less
then water. By some sort of mechanical motion--I believe a
bladder inside the thing was deflated by some process--the
density would increase so that it was greater than water, and
the probe would sink. While sinking, the fins would control the
attitude so it would sink in the direction of desired motion.
When at some predetermined depth, the thing would once again
mechanically alter its density--inflating a bladder?--and rise
to the surface. The control surfaces would again make the thing
rise in the desired direction. After one cycle, the probe will
have progressed a given distance.
The other day at school, a senior mechanical engineering class was
displaying projects out in the hallway. A group of fellows tried
building the apparatus above. Although I doubt their project ever
got wet it sure did spark a fire in me. I walked away sad that
probably nobody would continue their work as the whole concept
intrigues the hell out of me.
So list--is this salt-water BEAM power supply idea feasable? How
did the BEAM felleh(s) who already tried this idea fare?
ok..jef
Jeffrey D. Spears
University of Michigan
College of Engineering
``Double-E, can't spell gEEk without it!''
-Captain Gerald M. Bloomfield II, USMC
(my brother)
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