Alt-BEAM Archive
Message #07304
To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@bc.sympatico.ca
Date: Tue, 02 Nov 1999 17:31:02 -0800
Subject: [alt-beam] Re: aquabots - 'sealed' motor
Bob Shannon wrote:
>
> Asking the heat of a light bulb
> to change the density of a gas
> sufficiently to displace enough
> water to matter is not an efficient
I agree. But since we're tossing around all kinds of ideas, here's
another. Build into your aquabot a couple of thin plastic chambers, open
at the bottom and filled with (not entirely pure) tap water. In each
chamber place a small copper electrode. Hook up one electrode to the
positive pole of your power source and the other electrode to the
negative pole.
To increase bouyancy, apply power to the electrodes. You'll start
converting your water into hydrogen and oxygen (don't mix them!!!)
driving some water out the open bottom of the chambers. It shouldn't
take much for fine trimming.
To decrease bouyancy, simply wait (go do something else for a day or
two). They hydrogen will slowly bleed through the plastic and let water
back in to the chamber. (Yes, skeptics, it will. It even bleeds through
steel vessels, given enough time and a little pressure).
I know, it sounds kind of far out. Lots of potential for fooling around
though -- just keep matches away from it .
Bruce
7305 Wed, 03 Nov 1999 12:40:46 +1100 [alt-beam] Re: aquabots - 'sealed' motor Wilf Rigter Jacob Booth At 12:29 PM 11/3/99 +1000, you wrote:
>
>
>
>There was a post not long ago of a sub-bot that used wax heated through
>it's
>solid/liquid phase to change the buoyancy.
>
OK what about the bulb submersed in some LOW boiling point liguid. Like
that stuff in the 'drinking bird' toy... I think that may have been
something nasty like freon though. Maybe something like liquid butane may
be the go. It doesn't take much to get that stuff to boil.... (don't flame
me about safety! I think I outgrew burning off my eyebrows about 10 years
ago...)
>> Wouldn't it be a lot more efficient to drive a bimetalic strip attached
>to
>> a bellows?
>>
>> Store up power, then activate the ballast bladder, change depth, then as
>> the
>> strip recovers you return to your trimed depth.
>>
>> Asking the heat of a light bulb to change the density of a gas
>> sufficiently to
>> displace enough water to matter is not an efficient process.
>>
I still think a small bulb would use much less power than bimetalic,
cuprothal, nichrome or any other way of heating by current. Same goes for
actuators such as solenoids and nitinol. Maybe a used rocket igniter has
thin enough resistance wire... but I still think they need more current
than a bulb. The main principle I am trying to get here is a low power
source of heat, and using this heat in some way to effect buoyancy. Oh, and
I wanted to try something different :)
------------------------------------------------------------------
Jacob Booth BIS, MCP Web http://www.its.mary.acu.edu.au/
IT Services Email j.booth@mary.acu.edu.au
Phone (02) 97392235 Fax (02) 97392924
Australian Catholic University - MSM Campus Strathfield NSW
7306 Tue, 02 Nov 1999 18:25:01 -0800 [alt-beam] Re: directional antenna? beam@sgiblab.sgi.com Bruce Robinson Evan Dudzik wrote:
>
> okay, then, what is fast enough????? anything???
>
> --- Bob Shannon wrote:
>> Radio waves move at a foot
>> per nanosecond, TTL is not
>> fast enough.
Not too much. You're getting down toward the range where the length of
the traces on a circuit board can effect the accuracy of your
measurement.
Some systems (police radar, survey instruments) measure the phase shift
between two sources. In other words, the signals leave a transmitter
perfectly in phase and are received by two receivers. When the two
signals follow different length paths, there is a slight shift in the
phase of the signals, which can be measured.
If you can translate these ideas to a BEAM level, you have all sorts of
possible applications: distance sensors, speed sensors, position
sensors.
Bruce
7307 Tue, 02 Nov 1999 19:46:13 -0700 [alt-beam] MWT on PBS tonight - don't forget! beam@sgiblab.sgi.com Dave Hrynkiw If it isn't too late, check out PBS's "Scientific American Frontiers"
tonight. Robots, with a segment with our own MWT.
Later,
Dave
---------------------------------------------------------------
"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
2 vowels. Pronounciation? _SMITH_".
http://www.solarbotics.com
7308 Tue, 2 Nov 1999 22:18:22 -0800 [alt-beam] Re: MWT on PBS tonight - don't forget! "Rik" i just watched it --- no BEAM not even a mention!!!!
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