Alt-BEAM Archive
Message #12781
To: beam@sgiblab.sgi.com
From: CIRCITZ@aol.com
Date: Wed, 29 Mar 2000 23:18:55 EST
Subject: [alt-beam] Re: glider. A blimp is easier :-)
yeah, but the point is to do it yourself...I'd try to build one if I had the
time.
Dan
12782 Wed, 29 Mar 2000 20:13:56 -0800 [alt-beam] Re: looking for Stepper motors "'beam@sgiblab.sgi.com'" Wilf Rigter Those stepper photovores would be Steven Bolt's Sun Eater designs and the 2
phase (2 wire) stepper motors are from an electric clock mechanism. They are
normally driven with a series capacitor from an HC output. These steppers
have very low torque so they need a gearbox and are typically used with the
"seconds" output shaft of the clock driving the wheel. Afaik they only turn
in one direction.
regards
wilf
> -----Original Message-----
> From: Leonardo Boulton F. [SMTP:L.Boulton@rocketmail.com]
> Sent: Wednesday, March 29, 2000 11:50 AM
> To: beam@sgiblab.sgi.com
> Subject: looking for Stepper motors
>
> Hi, i found this photovore that works with an oscillator (square-wave),
> and it works with two stepper motors. Now, where can i found such
> motors.... i understand some clocks work with stepper motors, but are
> there any other places?....
> And, i don't have quite clear what the difference is between a stepper
> motor and a usual electromagnetic motor.....
>
> thx.
> Leo
>
>
>
> =====
> I'm here... http://geocities.com/l.boulton
>
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12783 Wed, 29 Mar 2000 23:30:22 EST [alt-beam] Re: glider. A blimp is easier :-) beam@sgiblab.sgi.com SkavenArmy@cs.com ive built it...it hit 10000 ft(remote altimiter) with a mylar case
12784 Wed, 29 Mar 2000 23:26:21 EST [alt-beam] Re: glider beam@sgiblab.sgi.com SkavenArmy@cs.com ive noticed...sorry gang!
12785 Wed, 29 Mar 2000 20:44:47 -0800 [alt-beam] Re: A biocore question???????????????????????? "'beam@sgiblab.sgi.com'" Wilf Rigter the input trigger or switching voltage is lower for a HCT chip
wilf
> -----Original Message-----
> From: Cory Houck [SMTP:riven280@hotmail.com]
> Sent: Wednesday, March 29, 2000 5:49 PM
> To: beam@sgiblab.sgi.com
> Subject: A biocore question????????????????????????
>
> can you use a 74hc240 and 245 instead of 74HCT240 and 245??????
> and what is the big difference with the middle numbers.
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com
12786 Wed, 29 Mar 2000 20:31:23 -0800 [alt-beam] Re: bicore head "'beam@sgiblab.sgi.com'" Wilf Rigter You probably mean those triangles which are symbols for inverters. The
74HC240 chip has 8 of those inverters inside of it. There are usually only 2
connections: one on the flat side, which the input and one on the point,
which is the output. The input controls the output. A positive input voltage
will cause a 0V output voltage and a 0V input will cause a +V output. The
numbers next to the triangles are the pin numbers of the chip. The 240 chip
inverters sometimes show a 3rd connection which are the Tristate enable pins
(1 and 19) and these are usually connected to pin 10 and 0V The inverters
are used for lots of things like amplifiers, oscillators or motor drivers.
As an example, if you connect a motor between 2 outputs and the first is 0V
and the other is +V the motor will turn one way. With the first output +V
and the other 0V the motor will turn the other way.
Does that sound like the answer to your question?
wilf
> -----Original Message-----
> From: Verne & Catherine Rambaud [SMTP:rambaud@worldnet.att.net]
> Sent: Wednesday, March 29, 2000 4:10 PM
> To: beam@sgiblab.sgi.com
> Subject: bicore head
>
>
> i really need to know what this triangle is, i can't find it. it has
> three
> leads and no values. where would a powersorce go. it isn't included but
> i
> think it goes on the opposite side of the motor so the power goes through
> the most parts. the schematic is the basic of basic bicores, it has like
> 8
> parts.
12787 Thu, 30 Mar 2000 14:47:46 +1000 [alt-beam] Re: glider. A blimp is easier :-) beam@corp.sgi.com, Justin Jacob Booth At 02:14 PM 3/30/00 +1000, you wrote:
>
>
>>This maybe a 'cool' idea, but its also a bad idea.
>>An automated R/C aircraft falls under the FAA rules if operating out of
>the
>>pilot's' sight.
>
>Methinks that having the necessary RC gear onboard but choosing not to
>use probably gets around this, because this means the plane is never out
>of your control - even if you're not controlling it :-)
>
>Personally, I'd be more interested in making a miniature helium blimp
>that navigates around the house, and it's a hell of a lot simpler to
>build (you could even use an off-the-shelf photopopper circuit if you
>really wanted to). "TPM" motors with tiny propellers put out a lot of
>thrust for their minuscule weight. (Unfortunately not _more_ thrust than
>their weight though, as far as I can tell...)
>
>Problem - actual balloons are no good for lift - they deflate after a
>while. The expelling pressure the rubber exerts on the gas is obviously
>a big factor, but as well as escaping through the knot, I wonder if the
>rubber itself might not be completely helium-proof. The first problem
>(rubber trying to expel the gas) is easily solved by using a slack
>bladder (reminds me of a Blackadder joke...), but if helium can actually
>pass through rubber, what else can it pass through - what material
>should we use that is helium proof?
>(I don't want to have to refill the thing will helium every few weeks).
>
The problem is that the Helium molecules are so small that they can migrate
through the rather porous (at that tiny scale anyway) rubber. Same with
plastic bags too. They can get around that very easily by 'metalizing' the
plastic. You know what I mean... they use metalized polyester - the shiny
metallic balloons you can get pre-filled with helium. It can take months or
years for them to lose buoyancy. I have thought about using an emergency
blanket (same metalized plastic) from a camping shop or 1st aid supplier to
custom make my own blimp...
cheers
Jacob
------------------------------------------------------------------
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
"Your lack of planning does not make it an emergency on my part"
12788 Tue, 28 Mar 2000 10:46:57 -0500 Re: glider Elmo
> Its been done.
>
> I am trying to find out the details for you, but a bunch of Aussies have
made an
> automated, self guiding aeroplane that is used to sample air quaility,
> temperature, humidity, wind speed and direction as it flys. It uses GPS to
> navigate and has flown itself from Australia to California on one tank of
fuel,
> sending back data as it went.
>
> For anyone in Australia who has Foxtel, they keep screening a short
10minute
> special about it between shows. I think it was done buy some guys at the
> University of New South Wales.....but i will look it up and let you know
when i
> track it down.
>
> Elmo
>
>
>
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