HDTenEightyP/NetNews huggingface dataset:
From: tedpan@techbook.com (Teddy Panarto)
Subject: Re: micro-stepping
Organization: TECHbooks of Beaverton Oregon - Public Access Unix
Date: Thu, 16 Apr 1992 19:27:14 GMT

litwack@dccs.upenn.edu (Mark Litwack) writes:

>I've got some questions on micro-stepping
>a stepper motor.

>First, how is it accomplished?  My first guess
>is that you would step the current in the active phase
>down a little bit as you stepped up the current in
>the next phase.  This would make the armature sit
>rotationally between the two phases.  Is this right?

Yes.


>If so, is there a linear relationship between the current
>in the two phases and the rotational position?  I.e.,
>if I applied 2/3 the current to phase A and 1/3 the current
>to phase B, would the armature sit 1/3 step away from A?
>If not, I guess I would have to use some kind of rotational
>feedback.

No. The current applied to each winding varies cosinusoidally
with the intended position where torque is proportional to
phase current, and the phase torque varies sinusoidally with
rotor position. Here's more detailed explanation if you're
into math:
Assume that TA = peak static torque at phase A
	    TB = ........................... B
	    iA = current at phase A
	    iB = ................ B
	     p = rotor teeth the motor has
	     a = intended position
	 theta = rotor displacement from one step position

Then,		 TA = -k iA Sin(p*theta)
		        T
		 TB = -k iB Sin(p*theta - pi/2)
			T
Note: Positive and negative currents are used to give a step length of
      pi/(2p) on each excitation.


And,
		 iA = I Cos(a)
		 iB = I Cos(a - pi/2)

The total torque T, from TA + TB, is equal to -k I Sin(p*theta -a)
						T
and the equilibrium position where load torque=0 is theta = a/p.

Therefore, we can control the rotor position anywhere (depending on the
resolution of the microstep) between the full-step position.
One should be aware of the accuracy if both the resolution  and the
load torque are high. Then you must use position feedback sensors.
For example: A system having 50,000 steps/rev can have +/- 50 - 100
microstep position errors if load torque is large enough.

I'm trying to be as accurate as possible, but please correct me if something
is wrong.


>Any good suggestions for micro-stepping controllers
>(chips, hybrids, board level)?

Not that I know of. There are full / half-step controllers out there on a
chip, just add drivers. If you really want to build a microstepper,
you can design it yourself using any single-chip processor and use a
lookup table for each microstep current, and use chopper driver to get
an optimum current at any position.

If anybody knows of such controller, please let me know.
Thank you.

-- 
tedpan@techbook.COM  ...!{sequent,nosun,uunet}techbook!tedpan
I'm not an employee here at TECHbooks, just a humble customer.
Newsgroups: sci.electronics,cmu.cs.robotics,comp.robotics
From: stu1f12@bnr.ca (Dave Malecki)
Subject: Re: Commodore help
Reply-To: stu1f12@bnr.ca (Dave Malecki)
Organization: Bell-Northern Research Ltd.
Date: Tue, 07 Apr 92 19:41:16 GMT

In article <Yds=uYG00VolEnD0oe@andrew.cmu.edu>, fc0v+@andrew.cmu.edu (Franklin Chang) writes:
|> Hi,
|>   I was wondering if anyone knows of a simple hack that will allow the
|> commodore 64 to work off dc battery supply.  I've heard that the
|> computer uses the waveform off the ac powersupply as a timer.  Recently

I don't know about that.  60 Hz seems awfully slow for a computer, even the
C64.  I know it runs at 1MHz (there's a crystal inside).  I believe the
9 VAC (is it 9 ?) is used to power the tape drive.  It may also be used for
the RF modulator, but I'm not entirely sure.  If you need a TTL level 60 Hz
oscillator, why not use a 555?  It would be quite simple to get a 50%
duty cycle square wave out of it at 0 to 5 VDC.  Hope this helps.



|> someone posted a solution to this problem, but it required a 60 hz (not
|> Mhz) oscillator and I'm at a lost to find a 60hz oscillator.  If any can
|> help, it is fairly urgent.  Our robot is going to a competition on the
|> Wed 8th.
|> Thanks
|> Frank
|> ***************************
|>    fc0v@andrew.cmu.edu
|>      Franklin Chang
|>  Carnegie Mellon University
|> ***************************


Dave Malecki

BNR owns, but does not share, my opinions.
Newsgroups: sci.electronics
From: jeg@desktalk.desktalk.com (John E. Greene)
Subject: Re: Chirping Chick Toy, interesting novelty...
Organization: Desktalk Systems Inc.
Date: Fri, 10 Apr 1992 18:24:09 GMT

In article <1992Apr10.180933.16598@desktalk.desktalk.com> jeg@desktalk.desktalk.com (John E. Greene) writes:
>In article <pschleck.702924799@odin> pschleck@odin.unomaha.edu (Paul W Schleck KD3FU) writes:
>
>	_________
>      /          \
>      |  epoxy   +---------+---------+
>s ----+   blob   |         |       +++++    <-I just looked at it with a 
>p ----+          |         /       -----      scope and this is reversed.
>e     |          |    1Meg \         |        Touching the conacts causes
>a     |          +---------+         |        one side of the 1Meg to go 
>k     |          |         |         |        high.
>e     \-------+--/        /          |
>r	      |          |           |
>	      |     0----|           |
>	      |           \          |
>	      |     0------+---------+
>	      |            |
> 	      +------------+
>

-- 
John E. Greene             Everyone needs something to believe in.  I believe 
Sr. Staff Engineer         I'll have another homebrew!
Desktalk Systems Inc.      
(213) 323-5998             internet:  jeg@desktalk.desktalk.com
From: lsls00@iliad.kodak.com (Ilia Levi)
Newsgroups: sci.electronics
Subject: Speaker repair advice needed
Date: 8 Apr 92 18:01:24 GMT
Reply-To: lsls00@iliad.kodak.com (Ilia Levi)
Distribution: na
Organization: Eastman Kodak

On my woofer the rubber seal that connects the cone to the frame is breaking
up. Where can one buy a replacement seal? I'd rather not buy the woofer.
These are Advent Small speakers. Thanks for any info.  
-- 


Ilia, levi@kodak.com
From: walden@mcclb0.med.nyu.edu (Paul Walden)
Newsgroups: sci.electronics
Subject: What is a SAWF?
Date: 15 Apr 92 15:56:15 GMT
Organization: NYU Medical Center, New York, NY 10016, USA

I came across the word "Surface Acoustic Wave Filter" the other day.  What 
exactly is such a device?  How does it work?  What is it made of?  What are 
they used for?

*****************************************************************************
Paul Walden, Ph.D.
Department of Biochemistry
550 First Avenue
New York University Medical Center
New York 
NY 10016                                  Internet: WALDEN@MCCLB0.MED.NYU.EDU
*****************************************************************************
Newsgroups: sci.electronics
From: wtm@uhura.neoucom.edu (Bill Mayhew)
Subject: Re: Mercury Memory
Organization: Northeastern Ohio Universities College of Medicine
Distribution: usa
Date: Fri, 17 Apr 1992 02:31:07 GMT

Thanks for the correction.  See below:






In article <1992Apr16.154303.23510@sbctri.sbc.com> tadams@wedge.sbc.com (Tom. Adams 529-7860) writes:
>
>A coherer was a dry device, consisting of very fine metal filings.
>A strong radio signal produced a change in resistance, which produced 
>a click in headphones.  The metal filings had to be tapped apart after
>every signal, and special mechanical devices called tremblers would
>periodically tap the coherer.  I believe you are thinking of the gas
>barreter (spelling?) which consisted of a fluid, often acid, and a needle 

-- 
Bill Mayhew      NEOUCOM Computer Services Department
Rootstown, OH  44272-9995  USA    phone: 216-325-2511
wtm@uhura.neoucom.edu   (140.220.1.1)
From: jimc@isc-br.ISC-BR.COM (Jim Cathey)
Newsgroups: sci.electronics
Subject: Re: Power Strip Surge Suppressors/EMI filters
Date: 8 Apr 92 00:54:19 GMT
Organization: ISC-Bunker Ramo, An Olivetti Company

In article <1992Apr6.202903.27693@u.washington.edu> whit@milton.u.washington.edu (John Whitmore) writes:
>iron (which is really hard to burn up).  There seems to be a lot
>of anecdotal evidence that modems/faxes and the like are sensitive
>to phone-line surges, which means (IMHO) that there are a lot
>of incompetent designers making telephone-connect equipment.
>...
>	I'm still not sold on phoneline surge arrestors, because
>they can be leaky enough to stop a phone from ringing... but if
>you're in a lightning-prone area, go ahead and try the surge
>limiter.  

I lost my modem in a lightning storm, and this model (a Prometheus
Promodem 2400G) has proven itself unreliable, as mine was the last to
die from the bulk purchase of 10 that a bunch of us made a couple of
years ago (hello incompetence).  I got it repaired (it was cheaper
than buying another modem, but not by a whole lot), and when I got it
back I wound the phone cord through a ferrite choke, and soldered a
couple of NE-2H bulbs in series across the back of the phone connector.
I used a couple of 1 Meg resistors to keep the bulbs balanced.  At
least the phone can still ring.  I'm hoping this cheesy hack will help
it live through lightning-induced surges.  Time will tell (or maybe the
net will!)

+----------------+
! II      CCCCCC !  Jim Cathey
! II  SSSSCC     !  ISC-Bunker Ramo
! II      CC     !  TAF-C8;  Spokane, WA  99220
! IISSSS  CC     !  UUCP: uunet!isc-br!jimc (jimc@isc-br.isc-br.com)
! II      CCCCCC !  (509) 927-5757
+----------------+
			"PC's --- the junk bonds of the computer industry"
Xref: sparky sci.electronics:8242 rec.bicycles:9014 rec.motorcycles:12649
From: xxxxajh@brunel.ac.uk (Alan J Holmes)
Newsgroups: sci.electronics,rec.bicycles,rec.motorcycles
Subject: Re: Sticky Demand Traffic Light problem solution
Date: 9 Apr 92 10:46:26 GMT
Reply-To: xxxxajh@brunel.ac.uk (Alan J Holmes)
Organization: Brunel University, Uxbridge, UK

In article <1992Apr3.150405.26793@rtsg.mot.com> sagerian@delphinium.UUCP (Steve M. Sagerian) writes:

>I guess I can explain it...most of you have missed the fact that these d







>I fact I was supprised no one mention that aluminum (sp?) wheels have no

>Stever
 
Is it just me and my terminal, was anyone else able to make 
anything of the above contribution?  I'm sure that the contributor
had something to say, but what was it?

Regards

Alan Holmes
From: geb@dsl.pitt.edu (gordon e. banks)
Newsgroups: sci.med
Subject: Re: Bernie S. Siegel
Date: 9 Apr 92 17:06:51 GMT
Organization: Decision Systems Laboratory, Univ. of Pittsburgh, PA.

From time to time reports such as this crop up.  To my knowledge,
whenever it is attempted to study it scientifically, making
suggestions to patients under anesthesia, the results haven't
been very positive.  Certainly patients do often hear and
sometimes even remember things from their operations.  Especially
when they get light but are paralyzed so can't move.  THis can
be quite unpleasant.  Usually the autonomic response (fast heart
rate, etc.) alerts the anesthesiologist and he puts them deeper
under.  Maybe Dr. Gaba is still around and can comment.

-- 
----------------------------------------------------------------------------
Gordon Banks  N3JXP      | "I have given you an argument; I am not obliged
geb@cadre.dsl.pitt.edu   |  to supply you with an understanding." -S.Johnson
----------------------------------------------------------------------------
From: Linda.Cummings@f34.n375.z1.fidonet.org (Linda Cummings)
Newsgroups: sci.med
Subject: MRI
Date: 15 Apr 92 13:36:13 GMT
Organization: FidoNet node 1:375/34 - Batteries Included, Montgomery AL


 > From: gibbs2@milori.ccit.arizona.edu (Alex R. Gibbs)

 > I have had ear trouble, possibly due to noise exposure, and my
 > main fear is the sound level of the thumping.  I have heard that
 > it can be quite loud and that people wear earplugs often.  What I want to
 > know is HOW
 > loud is it?  I don't want to risk further damage to my ears.  I
 > realize that it must be "safe" but my ears may be overly sensitive.

Knowing your "weak" point in the beginning is good, Alex.  I would suggest 
that you wear ear plugs if you ears are that sensitive.  I've had a total of 3 
MRI's myself.  The first one was really nice.  They had music piped in to 
distract you from the "knocking."  The second and third didn't have music, but 
the knocking wasn't too bad.  It sounds like a very fast knocking on the door 
if you're right next to the door. The knocking also is not continuous.  There 
are periods where you don't hear anything.  By being aware of exactly what 
will happen in an MRI is half the battle, though.

The first one made me think about how small the area was I was in.  I told my 
husband that I now knew what it was like to be in a coffin!  The second and 
third ones, however, I was well aware of what it was going to feel like and 
therefore went through them just fine.  But, I would, if I were you, go ahead 
and take your ear plugs just to be on the safe side. Also, they can hear you 
when you are in the MRI.  If the noise is still too loud, then let them know.  
They might be able to do something about getting something else over your ears 
to protect them.  Since you can't have anything metal on you, regular 
earphones (like for the stereo) are out.  Also, if you don't like tight 
places, wear a blindfold.

It's really not too bad to have an MRI.  The only problem I had was that my 
scan was for the lumbar area and even though my knees were slightly elevated, 
they had to pull me up to a sitting position because I became so still that I 
could not get up by myself.

Good Luck!

Linda


 

--  
Uucp: ...{gatech,ames,rutgers}!ncar!asuvax!stjhmc!375!34!Linda.Cummings
Internet: Linda.Cummings@f34.n375.z1.fidonet.org
From: joshua@Veritas.COM (Joshua Levy)
Newsgroups: sci.med
Subject: looking for info on AMPEF
Date: 10 Apr 92 15:46:39 GMT
Organization: VERITAS Software

Sorry if this in in the wrong group.  I couldn't think of a better one.

Does anyone know about Americans for Medical Progress Education Foundation?
Their slogan is ``Research saves lives'' and their goal is to ``spearhead
the critical effort to educate American opinion leaders and citizens about 
the need for animal research.''  (All quotes are from a full page add in
the WALL STREET JOURNAL.)

My key questions about this group is:
    1. What to they do?
    2. How much of their money goes to that (as opposed to admin and
       overhead)?
    3. Where do they get their money from?

I don't want to start a general animal/research rights argument.
I do want to know if these people do what they say they do, and how
good they are at it.

Joshua Levy  (joshua@veritas.com)
Newsgroups: sci.med
From: yazz@locus.com (Bob Yazz)
Subject: Re: Class action against FDA
Date: Fri, 17 Apr 1992 03:46:38 GMT

dsr@chickpea.mitre.org (Douglas S. Rand) writes:

| Just so I don't come off as entirely snide.

You failed.
-- 
Ever cautious, Motives pure; Safe and effective, Who could demur?
Lead, follow or get out of the way.  Unless, of course, you're the FDA.
Newsgroups: sci.med
Subject: Re: O2 a "prescription-only" drug?  Why?
From: macridis_g@kosmos.wcc.govt.nz (Gerry Macridis)
Date: 14 Apr 92 15:56:36 GMT
Organization: Wellington City Council, Wellington, NZ
Summary: Oxygen not so innocuous

In article <1992Apr10.154558@ddxrus.enet.dec.com>,
fgz@ddxrus.enet.dec.com (Federico Genoese-Zerbi) writes:

> Now I understand that there are some dangers inherent in the use of
> Oxygen, and people who should not be given oxygen at 100% except
> along some clear guidelines, but compared to some of the other stuff
> available over the counter, this is one innocuous substance.

Administration of oxygen can be fatal if you were not properly trained
in its use.  A patient with chronic obstructive pulmonary disease can
develop respiratory arrest with concentrations of oxygen above 28%.

-- 
Gerry Macridis,      /\/\     .... Email: macridis_g@kosmos.wcc.govt.nz
Private Box 3929,   ( oo )    :... Voice: +64 4 3899444
Wellington,           \/......:
New Zealand.                       Learn first aid; it saves lives.
Newsgroups: sci.med
From: young@sasquatch.serum.kodak.com (Rich Young (x37176))
Subject: Re: Adverse effects of grilling on gas/charcoal/electric flame?
Organization: Clinical Products Division, Eastman Kodak Company
Date: Tue, 7 Apr 92 16:36:23 GMT

In article <68851@ut-emx.uucp> shoroff@ccwf.cc.utexas.edu (Bart Simpson) writes:
>I'm not sure if this topic has been discussed a lot before, if it has 
>been, someone please get me up to speed with the discussion.
>
>I've heard that grilling (meats etc) on gas flames and charcoal exposes 
>the meats to a lot of hydrocarbons which are carcinogenic. How true is 
>this? Is there no problem with grilling on an electric grill?

	I don't have a document in front of me (and probably shouldn't be
	posting this), but I seem to recall that there were certain
	carcinogens which do occur as a result of char-broiling.  If one
	uses charcoal, the starter fluid can leave benzenes unless it is
	allowed to burn away completely.  The charred surface of the meat
	contains protein breakdown products which are suspected carcinogens,
	including, I believe, nitrosamines.  I seem to recall that it was
	the exposure of the meat to combustion products and direct flame
	which tended to cause the formation of the noxious chemicals, and
	that, as a result, broiling in an oven was far less hazardous, BUT
	PLEASE REMEMBER, I'm really scraping the bottom of the memory barrel
	here!

	There is an excellent article in SCIENCE NEWS, Vol. 140, No. 4,
	July 27, 1991, pages 60-61, which discusses pollution effects of
	outdoor cooking, and which also details some of the chemicals produced
	by this type of cooking.  It may be of some use in your research.

-Rich (young@serum.kodak.com)

-------------------------------------------------------------------------------
These are MY opinions, don't blame them on my employer.

Don't get angry, get accurate information.
From: hollombe@polymath.tti.com (The Polymath)
Newsgroups: sci.med
Subject: Re: Suicide prevention; what next?
Date: 10 Apr 92 20:22:59 GMT
Organization: The Cat Factory

In article <4647@cluster.cs.su.oz.au> allanc@cluster.cs.su.oz (Restless Wanderer) writes:

}Someone related to me that ... the exhaust
}of an UNleaded car will not kill you.

This is utter nonsense -- and extremely dangerous nonsense at that.

}Now I assumed that it was the carbon monoxide that was the problem.Not
}so said my friend but the lead content.
}I find this hard to believe,but according to an ambulance paramedic it would
}take longer to kill y'self if you used unleaded cf leaded.

Carbon Monoxide (CO) is very poisonous.  It binds to the hemoglobin in
blood 100 times more efficiently than oxygen.  It takes only 2 or 3%
concentration in the ambient atmosphere to do you in fairly quickly --
certainly more quickly than any case of lead poisoning.

Modern vehicles that use unleaded gas are generally better tuned and run
leaner fuel/air mixtures than the old lead eaters.  Thus, they will
produce less CO in their exhaust and take slightly longer to do you in.

Tell your friend to test his theories on himself before he goes handing
out life-and-death advice to others.  (1/2 (-: )

The Polymath (aka: Jerry Hollombe, M.A., CDP, aka: hollombe@soldev.tti.com)
Head Robot Wrangler at Citicorp                   Turn the rascals out!
3100 Ocean Park Blvd.   (310) 450-9111, x2483     No incumbents in '92!
Santa Monica, CA  90405 {rutgers|pyramid|philabs|psivax}!ttidca!hollombe
From: hollombe@polymath.tti.com (The Polymath)
Newsgroups: sci.med
Subject: Re: O2 a "prescription-only" drug?  Why?
Date: 15 Apr 92 23:33:06 GMT
Article-I.D.: ttidca.34603
Organization: The Cat Factory

In article <1992Apr15.162016.24816@kestrel.edu> king@reasoning.com (Dick King) writes:
}In article <14355@pitt.UUCP> geb@dsl.pitt.edu (gordon e. banks) writes:
}>In article <1992Apr10.154558@ddxrus.enet.dec.com> fgz@ddxrus.enet.dec.com (Federico Genoese-Zerbi) writes:
}>>
}>>New Hampshire and finished off the module fine.  Imagine my surprise
}>>when I found out that in Massachusetts you need a prescription to
}>>buy the stuff....
}>>
}>Tell them you are taking up welding.
}>
}
}Please imagine a smiley.
}
}Breathing gases necessarily have purity requirements that industrial gases
}don't.  I'm not sure about O2 in particular, but ask your local SCUBA shop.
}
}The contaminant i would worry about is oil.  If i knew more about how
}industrial O2 was made i would probably be able to figure out other
}contaminants to worry about.

Oil in a pure oxygen atmosphere -- what a concept! (One of the first
things they teach you in welding class is _never_ use pressurized oxygen
to blow off a surface.  If you happen to hit an oily patch it will
instantly drop the oil's flash point below room temperature.  Boom.)

It's been a while since I've done any serious welding, but a friend has an
acetyline rig in his garage.  The oxygen bottle is labeled "Aviator's
Oxygen." That means it's the same as medical oxygen, except it's been
dried to avoid possible fogging of masks or goggles.  As I noted in an
earlier post, welders are very picky about the purity of their gasses.

The Polymath (aka: Jerry Hollombe, M.A., CDP, aka: hollombe@polymath.tti.com)
Head Robot Wrangler at Citicorp                   Turn the rascals out!
3100 Ocean Park Blvd.   (310) 450-9111, x2483     No incumbents in '92!
Santa Monica, CA  90405 {rutgers|pyramid|philabs|psivax}!ttidca!hollombe
From: Linda.Cummings@f34.n375.z1.fidonet.org (Linda Cummings)
Newsgroups: sci.med
Subject: Temperatures
Date: 13 Apr 92 03:19:13 GMT
Organization: FidoNet node 1:375/34 - Batteries Included, Montgomery AL

Can anyone tell me if a normal temperature is 98.6 what a normal skin 
temperature would be?  I've just been through a session in Birmingham at the 
pain clinic where they put little biodots on our hands.  When relaxing, she 
said the body temperature would rise and the dot would change color (sort of 
like the old mood rings).  If I could find a skin thermometer in the range 
needed, that would be great!  So far, I haven't been able to find one low 
enough to indicate skin temperature.  Any suggestions?

Linda


 

--  
Uucp: ...{gatech,ames,rutgers}!ncar!asuvax!stjhmc!375!34!Linda.Cummings
Internet: Linda.Cummings@f34.n375.z1.fidonet.org
Newsgroups: sci.med,misc.kids
From: dyer@spdcc.com (Steve Dyer)
Subject: Re: Lime juice and lots of sun
Organization: S.P. Dyer Computer Consulting, Cambridge MA
Date: Thu, 16 Apr 1992 00:01:06 GMT

In article <1992Apr15.175739.26961@tandem.com> day_kevran@tandem.tandem.com (Kevran Day ) writes:
>> There is a psoralens compound in lime juice and in figs.  When this
>> chemical is present and the body is exposed to intense sun light
>> blotches will come up on the skin.
>
>This is very interesting!  I remember that in college some friends were taking a 
>"tanning" pill called Trisoralen (sp)!  Of course, this was many years before the
>skin cancer consciousness brought us sunblocks to SPF 30!  The tanning pill had
>to be prescribed and was very effective.

Trioxsalen (tradename, Trisoralen--you got it right) is a psoralen
used to treat vitiligo and to enhance tanning.  It can cause a
nasty burn if you're not exquisitely careful about following the
timed schedule of exposures to the sun over successive days.
That is, it's not an innocuous drug.

I tried it years ago; it made me itch all over.  I don't think
that's a common side-effect, but it squelched my enthusiasm for
further experimentation.

-- 
Steve Dyer
dyer@ursa-major.spdcc.com aka {ima,harvard,rayssd,linus,m2c}!spdcc!dyer
Newsgroups: sci.med