HDTenEightyP/NetNews huggingface dataset:
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.electronics
Subject: Re: Ohm's law for AC?
Date: 13 Apr 92 17:05:59 GMT
Organization: University of Georgia, Athens

What was the impedance at the end of the cable?  That is, what were you
using for a load?

The circuit looks like this:

             R1
       -----//////--------+
Signal                    / R3
source                    /
       -----//////--------+
             R2

Here R1+R2 is the resistance of the cable, and R3 is the resistance of the
load (the thing you're measuring the voltage at).

Let V represent the voltage at the source.  Then the voltage across R3
will be   V * R3 / (R1 + R2 + R3).

If R1+R2 = 5 ohms and R3 = 10 million ohms (the normal input impedance of
a digital multimeter) then R1+R2 will be negligible.
-- 
==========================================================================
Michael A. Covington, Ph.D. |  mcovingt@uga.cc.uga.edu  |  ham radio N4TMI
Artificial Intelligence Programs | U of Georgia | Athens, GA 30602  U.S.A.
==========================================================================
From: jeh@cmkrnl.com
Newsgroups: sci.electronics
Subject: Re: Jacob's Ladder
Date: 13 Apr 92 16:30:36 GMT
Distribution: na
Organization: Kernel Mode Consulting, San Diego CA

In article <1992Apr8.161347.3926@ole.uucp>, ray@ole.uucp (Ray Berry) writes:
> rdi@cci632.cci.com (Rick Inzero) writes:
> ...
>>Note that there exist some big neon sign transformers.  Mine
>>is rated 15,000 volts at *3000* ma.  This most certainly would
>           ^^^^^^^^^^^^^^^^^^^^^^^^^^
> 	Must be a real honker- 15 KV * 3 A = 45 KVA :-).. Pray tell, how many
> hundreds of pounds does it way [sic], and for what purpose was it designed?  Curious
> minds...

For that matter, what do you power it with?  That's more power than an entire
house is typically supplied with (residential 100-amp service). 45 KVA would
eat 125 A from *all three phases* of 120/208 "wye" three-phase.  

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: sci.electronics
Subject: Re: Serial Data over RF
Date: Sun, 12 Apr 92 10:40:18 PDT
Organization: The Portal System (TM)
  <ww-jtrnnagle@netcom.com> <1992Mar25.144354.1195@cfctech.cfc.com>
  <1992Mar28.011507.28876@ctr.columbia.edu> <-xcj2janagle@netcom.com>

Siemens has just announced their PMB2200 and PMB2400 RF transmitter/receiver
chip set.  '2200 is the transmitter.  Despite the implications of the
part numbers, these chips are supposed to handle data rates up to 500 kbaud.
RF carrier frequency is in the 700 MHz - 1 GHz range.  Price is $7.85
for either chip in 1K quantity.  Contact Ramesh Sirsi (I believe he is
the product marketing manager) for more information.  His number is
(408) 980-4536.  The chips are currently in volume production.
The chips are only available in a small-outline package.
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.electronics
Subject: Re: Jacob's Ladder
Summary: Fluorescent light ballasts are not transformers
Date: 6 Apr 92 20:33:32 GMT
Organization: University of Georgia, Athens

In article <z2zt1ta@rpi.edu> richtt@aix.rpi.edu (Timothy G. Richter) writes:
>
>So far, everyone has mentioned neon sign transformers.  What about fluorescent
>ballasts, as they are high voltage step-up transformers, also?
>
They are not transformers; they are current-limiting inductors.  Fluorescent
lights work at 120 volts with heated cathodes.  The cathodes are heated
initially like heating elements, and are then kept warm by the current
through the bulb.



-- 
==========================================================================
Michael A. Covington, Ph.D. |  mcovingt@uga.cc.uga.edu  |  ham radio N4TMI
Artificial Intelligence Programs | U of Georgia | Athens, GA 30602  U.S.A.
==========================================================================
Newsgroups: sci.electronics
From: berger@atropa (Mike Berger)
Subject: Re: DC Shock
Organization: University of Illinois at Urbana
Date: Sun, 12 Apr 1992 20:13:21 GMT

kolstad@cae.wisc.edu (Joel Kolstad) writes:
>Oh, please.

>Shock, in the sense Jon means, is NOT torture.  It's simple the slightly
>undesirable sensation of current running through the skin.  Go put a nine
>volt battery on your tongue.  You probably won't like it, but it's far
>from torture.
*----
You're right - I wouldn't like it at all.  And it most certainly WOULD
look like torture to me if somebody strapped a collar around me that
could shock me at HIS discretion, and I have no control over it.

>If dogs were smart enough that you could tell them not to wander outside
>their yards, fine -- maybe we wouldn't need shock collars.  But they can't,
>and the only thing that a dog is going to understand when its master isn't
>standing right over it is some remote physical stimulation -- high frequency
>sound, shocks, or whatever.
*----
If owners were responsible enough to take proper care of their dogs, they
wouldn't resort to torture devices.  Shock collars are not a constructive
or positive way to teach a dog anything but fear.  I know many well-behaved
dogs that didn't need pain and fear to teach them.

>If you want to talk about taking this idea a little too far, perhaps we should
>discuss cattle prods.  I've been told that these things are quite painful to
>the beast of which they're applied...
*----
Nobody asked for help with a cattle prod, or I might have replied similarly.

>Finally, if you meant this humorously, you can disregard the above.  But
>I didn't see a smiley...
*----
You really think it's funny?!
--
	Mike Berger
	Department of Statistics, University of Illinois
	AT&TNET     217-244-6067
	Internet    berger@atropa.stat.uiuc.edu
From: tomb@hplsla.hp.com (Tom Bruhns)
Date: Wed, 1 Apr 1992 19:07:20 GMT
Subject: Re: Blue LED (was Re: LED limitations on FPDs)
Organization: HP Lake Stevens, WA
Newsgroups: sci.electronics

parks@gibbs.physics.purdue.edu (Chris Parks) writes:

>True blue (~470nm wavelength) LED's have just been developed by 
>3M and Purdue.  They are made from ZnSe/ZnCdSe quantum well 
>heterostructures which can also be made into blue semiconductor lasers
>with a power output of a few hundred milliwatts.  
>They're not commercially available yet.  The main holdup in 
>improving the technology is better p-type doping of II-VI alloys.

How does this "true blue" differ from the SiC blue LEDs from Cree?
Digi-Key lists them at 470nm peak wavelength, and $2.80 each or
only $.93 each in 1000's.

Newsgroups: sci.electronics,comp.misc
From: alasnik@casbah.acns.nwu.edu (Adam Lasnik)
Subject: Will air ionizer harm diskettes and computer?
Organization: Northwestern University, Evanston, Illinois
Date: Thu, 16 Apr 1992 22:59:35 GMT


Hi folks.

I just bought a brand new air ionizer that's supposed to charge approximately
18 cubic feet of air per minute.  Problem is that I just realized that my
computer hard disk and floppy disks might be in danger due to the electrically
charged particles.

I live in a small single college dorm room (about 20 by 15 feet)... Do I need
to truly worry about my electronic media, and if so, what can I do to protect
them?  Or do I just have to return my air ionizer?

Please mail your responses PRIVATELY via e-mail, and I will happy to post a
public followup if there is interest.

Thanks so much for your help.

--ADAM "KEYS" LASNIK
Xref: sparky sci.electronics:8271 comp.dsp:1094 sci.engr.biomed:209 sci.math:5851
From: larryd@milton.u.washington.edu (Larry Desoto)
Newsgroups: sci.electronics,comp.dsp,sci.engr.biomed,sci.math
Subject: Re: quaternians, tracking, 3 dimensions
Date: 10 Apr 92 00:08:10 GMT
Article-I.D.: milton.larryd.702864490
Organization: University of Washington

berrier@sweetpea.jsc.nasa.gov (K. Berrier 283-4125) writes:

>A quaternion is a transformation matrix consisting of a scalar 
>and a vector.  The scalar is the angle of rotation about the 
>axis represented by the vector.

>They are often used to represent the relationship between two 
>coordinate systems since there are only four elements instead 
>of the usual nine. (Decreasing the number of calculations 
>required and increasing speed of computation.)

>I cannot direct you to a particular source but it would probably 
>be worth your while to learn about them.


Some references that might be of interest:
 
B.K.P. Horn, "Closed-form solution of absolute orientation using unit
quarternions," J. Optical Society of America A, Vol 4(4):629-642, April
1987.
 
B.K.P. Horn, H.M. Hilden, and S. Neghdaripour, "Closed form solution for
absolute orientation using orthonormal matrices," J. Optical Society of
America A, Vol 5(7):1127-1135, July 1988.

--
Larry                                   |   Thunder makes all the noise;
                                        |   lightning gets the job done.
larryd@milton.washington.edu
I have my opinion; the university has its own.
From: glenn@prism.gatech.EDU (Glenn Souther)
Newsgroups: sci.electronics
Subject: VCR+ algorithm wanted
Summary: want algoritm to map time into vcr+ code
Keywords: vcr, vcr+, gemstar
Date: 15 Apr 92 14:57:36 GMT
Distribution: usa
Organization: Georgia Institute of Technology

I have been trying to find out the algorithm employed in the
vcr+ that maps a given date, time, channel, and program length into
the appropriate vcr+ code.  I would prefer not to attempt to 
decode the things myself, and I heard that someone on this 
group might be willing to email me the algorithm or a program
that will do it for me. Any help?

Glenn Souther
Office of Information Technology
Georgia Insitute of Technology, Atlanta Georgia, 30332
InterNet: glenn@vail.gatech.edu      Ma Bell:  (404) 894-6176
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.electronics
Subject: If we can't read it we can't answer it
Summary: Spelling matters, to a degree
Date: 11 Apr 92 14:18:32 GMT
Organization: University of Georgia, Athens

It's traditional not to criticize spelling errors in net postings,
because most people are typing fast, and some of them are using
editors where it's hard to make a correction.

HOWEVER, we've recently had some messages that went far beyond ordinary
typing errors, and became real puzzles for the reader.  Spellings that
I recall recently are...

"droor"             (turned out to mean "drawer")

"wala"              (I think this was supposed to be "voila")

"to" meaning "2" (resulting in a very confusing sentence,
                  because in that context, "to" also almost made sense)

Please, folks, make sure you're writing in English or some other human
language.  If we can't read it, we can't answer it.  


-- 
==========================================================================
Michael A. Covington, Ph.D. |  mcovingt@uga.cc.uga.edu  |  ham radio N4TMI
Artificial Intelligence Programs | U of Georgia | Athens, GA 30602  U.S.A.
==========================================================================
Xref: sparky sci.electronics:8325 rec.bicycles:9180 rec.motorcycles:12882
From: sasmjw@laverda.unx.sas.com (Martyn J. Wheeler)
Newsgroups: sci.electronics,rec.bicycles,rec.motorcycles
Subject: Re: Sticky Demand Traffic Light problem solution
Date: 10 Apr 92 19:09:13 GMT
    <1992Apr3.150405.26793@rtsg.mot.com> <3949@mercury.brunel.ac.uk>
Reply-To: sasmjw@unx.sas.com
Followup-To: rec.bicycles
Organization: SAS Institute Inc. Cary NC
Originator: sasmjw@laverda.unx.sas.com
X-Bytes: 1354

In article <3949@mercury.brunel.ac.uk>, xxxxajh@brunel.ac.uk (Alan J Holmes) writes:
>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?


He was probably trying to provoke another bi/motor flame war by
cross-posting a bicycle post to rec.motorcycles.  Just to make sure it
irritated as many people as possible, he took out all the carriage
returns from his post.

:-)

Martyn
-------------sasmjw@unx.sas.com----(Martyn J. Wheeler)----DoD #293------------
SAS Institute, Inc: (919) 677-8000 ext.7954    H: (919) 839-0092 (Raleigh, NC)
          "If you spin, you deserve to die" -- Mike Hawthorn
       "I love competition, but I hate conflict" -- Alain Prost
-- 
Martyn
-------------sasmjw@unx.sas.com----(Martyn J. Wheeler)----DoD #293------------
SAS Institute, Inc: (919) 677-8000 ext.7954    H: (919) 839-0092 (Raleigh, NC)
          "If you spin, you deserve to die" -- Mike Hawthorn
       "I love competition, but I hate conflict" -- Alain Prost
Newsgroups: sci.electronics,comp.dsp,sci.engr.biomed,sci.math
From: luzeaux@liszt.berkeley.edu (Dominique Luzeaux)
Subject: Re: quaternians, tracking, 3 dimensions
Reply-To: luzeaux@liszt.berkeley.edu (Dominique Luzeaux)
Organization: University of California
Date: Tue, 14 Apr 1992 17:30:00 GMT

In article <1992Apr13.161433.25003@ircam.fr>, francis@ircam.fr (Joseph
Francis) writes:
|> I believe quaternions are rational extensions into threespace of
|> imaginary numbers, you get from "x + iy" to "x + iy + jz" (or I guess
|> for EE's, it would be "x + jy" and "x + jy + kz") where i,j have
|> traditional square-root-of-negative-one meanings. I can't remember
|> exactly, it was only interesting to me for playing with 3d extensions
|> of the ordinary Mandelbrot set graphics generator functions.

As wrote berrier@sweetpea.jsc.nasa.gov (K. Berrier 283-4125) in a previous
article, a quaternion can be seen as a transformation matrix consisting of
a scalar and a vector, where the scalar is the angle of rotation about
the axis represented by the vector.

Actually, the quaternions are the first non commutative field which is an
extension of R; a quaternion can be written: a + ib + jc + kd , where
i^2=j^2=k^2=-1, ij=k, jk=i, ki=j, ji=-k, kj=-i, ik=-j
In other words, the field of quaternions can be seen as the affine space R^3
where (i,j,k) is an orthonormal base for the underlying vector structure,
and the product of any two combinations of i,j,k can be seen as the vector
product of the corresponding vectors in R^3.
One of the interesting things about quaternions is that they can be seen
as rotations, and the product of two quaternions yields the product in the
affine space R^3 of the two corresponding rotations.

Quaternions are only an example of hypercomplex fields; you can define the
octavions, which form the first non associative field which is an extension 
of R (you have to introduce 7 objects, like the previous i,j,k, with 
appropriate relations).

	Dominique Luzeaux
Newsgroups: sci.electronics
From: zardoz@rx-db (zardoz@rx-db.hf.intel.com)
Subject: Re: HV shocks (was: Jacob's ladder)
Organization: Intel Development Tools Operation, Hillsboro, OR
Date: Thu, 16 Apr 92 16:34:07 GMT

Shock, but true:

While I was working with industrial induction heating equipment, I experienced
the worst shock of my life.  We had a test setup for new inverters, and triple
'0' locomotive cables of 480V 3ph. hanging around.  Normally I was very careful
because not only was there a lot of juice (480V input, 750V DC bus, 1500V peaks
on the 3-10khz output), but they were water cooled and of course always leaked
onto the floor.  One day I turned on the wrong 500A breaker, walked behind a
big inverter cabinet, and promptly ran my head into a live locomotive cable
hanging from a 2x4 between boxes.  Ahhhhh!!  My head was a big balloon that was
being inflated much too far.  I was looking out through a green translucent
force field.  Sparks were flying.  Fortunately, when my head contacted the
cable it caused one of the other phases to short to a grounded cabinet and
trip the 500A breaker.  It was over in a moment and I was running.  A co-worker
said he heard the noise, saw a big flash, turned around and I was gone.
I know what Ted Bundy felt like.  I was wearing cowboy boots and standing on
the usual damp concrete floor.  It was only 277V to ground from a wye, of
course.  My boss came out and asked me if it was my "first big one".
We used to use a big tank of water with hanging aluminum plates for a test
load.  One fellow decided to pour more salt water in from a metal bucket
while the thing was running.  Ahhhh!  Worse than pissing on an electric fence!
A customer told me of getting his hand wrapped around the fat braid to one
of the DC input diodes.  277V and he couldn't let go.  So he brought his
other hand up to yank his arm away.  But it somehow grabbed the next diode
braid and the other phase!  Now he had 480 (more like 510V) across the
hands.  Luckily they were pressed together, so it probably didn't go through
his whole body.  He collapsed into the box, yanking his arms off the 3/4"
diode braids.  How he missed the 750V DC buss made of water cooled 1/2"
copper pipe, I don't know.  It was in the bottom of the box.
The RF units were the most dangerous.  10,000V at 5A made a big input xfrmr.
And with the Q of the giant tank circuit, lots of high voltage around.
I had heard horror stories of people just pointing at something from 6 inches
or more and getting fried to heaven.  On the site, customers would point
to something and I would yell "Don't do that!".
Other items too numerous to mention.  I did field service on induction
heaters for a couple of years and met lots of HV, explosions, sparks, etc.
Our biggest product was 1.2MW and I had to go the Niagara Falls to fix it.

Now its only 5V and not very scary.

WA7LDV


-- 
Fan mail may be sent to:
zardoz@rx-db.hf.intel.com
From: jagnow@al.weeg.uiowa.edu (Al Jagnow)
Newsgroups: sci.electronics
Subject: Re: Paranoid about my hz?
Date: 6 Apr 92 20:18:06 GMT
Reply-To: jagnow@al.weeg.uiowa.edu (Al Jagnow)

In article <26MAR199218312769@elroy.uh.edu> englhq@elroy.uh.edu (Franklet,  
Duane L.) writes:
> This is a simple question for any of you. If I want to use an over the
> counter step down transformer so that I can use my printer in Germany,
> do I need to be concerned about the difference in hz?
> 
> I have been told that what goes in comes out, so I will be feeding
> the printer 110 at 50 hz, and the printer specs say the source should
> be 110, 60hz plus/minus 3hz. 
> 
> Plenty of guys at the local store are going to say, Yeah, go for
> it, no problem, but I wanted to get a second opinion.
> 
> Thanks in advance
> 
> Duane Franklet
> englhq@jetson.uh.edu 

You need to know more about your printer.  Most printers don't care.  Some  
printers use the 60Hz as a timing reference. Character spacing may change if  
you change the frequency too much.  I seem to remember that Apple said that one  
of their printers could be damaged by operation at the wrong frequency.  Check  
with the manufacturer for details.

Al Jagnow
jagnow@al.weeg.uiowa.edu









Al Jagnow
From: gary@ke4zv.uucp (Gary Coffman)
Newsgroups: sci.electronics
Subject: Re: RS-232 Ambient temprature sensor
Keywords: hardware project
Date: 8 Apr 92 09:00:04 GMT
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Organization: Gannett Technologies Group

In article <1992Apr5.013215.11028@ttank.ttank.com> karl@ttank.com writes:
>Okay, I know it has been brought up before but, I haven't seen any
>REAL aplication of all the therory that has been thrown around here.
>
>What I would like to build is a Thermometer that can communicate
>ambient temprature to a computer via RS-232.  I would like to tie
>this information into my X10 monitoring program so it could turn
>on the A/C etc.
>
>I imagine it wouldn't have to be too complex.  Any math etc that
>might be needed can be done in software on the host.

Well, I wouldn't bother with RS232, but you could do it to a parallel
port quite easily like this:

  x------------------------------------------------ to parallel B0
  |
  x----/\/\/\---x    ----------\
         Tr     |    |          \
                x----x OPamp     \
                |    |            \
              -----  |             >----- to parallel paper out line  
          C   -----  |           /
                |  x-x         /
                |  | |________/
                |  |
              ---- |
              ///  |
 +5-/\/\/\---------x-----/\/\/\---x
      R1                   R2     |
                                _____
                                / / / 



Write a 1 to B0 and measure the time it takes for the paper out line to
toggle. By setting the ratio of R1/R2 so that the opamp toggles in one
TC, you now know the resistance of the thermistor Tr. You can now do a
table lookup, or calculate the temperature from this value.

That's the simplest circuit I can think of. For higher accuracy, you
could use one of the IC temperature to voltage converters, an A/D
converter, a microprocessor to format the reading into serial data,
and a 1488/1489 pair to communicate by RS232. Or a single chip
micro with built in A/D could be substituted for the A/D and micro
combination. Talking RS232 requires at least a UART and a parallel
loader/data formatter. A micro is the simplest way today.

Gary
From: wa2ise@cbnewsb.cb.att.com (robert.f.casey)
Newsgroups: sci.electronics
Subject: Degaussing color monitors
Keywords: coil
Date: 17 Apr 92 18:53:42 GMT
Organization: AT&T


Organization: AT&T Bell labs

In article <7480046@hpfcso.FC.HP.COM> myers@hpfcso.FC.HP.COM (Bob Myers) writes:
>internal degaussers are
>simply not strong enough to do the job.  (They're really intended to keep the
>"normal" build-up of magentism down.)  You will very likely have to get a
>degaussing coil and perform a manual degaussing.
These coils are about 9 inches in diameter, and usually have a pushbutton.
procedure:  first, put your wallet (with your ATM and credit cards) in some
distant safe place.  Plug in the degaussing coil.  You probably should turn
the monitor off.  A few feet away from the monitor, activate the coil.
Then move it to the monitor screen and move it around in circular motions.
Wiggle it around several times.  Then move the coil away about 6 feet
before you turn it off.  And be sure to do all of this quicky before the
coil gets real hot!  The coil should have instructions for degaussing
your color TV (which in this respect is the same as your monitor).
ALSO IMPORTANT!***  DO NOT degauss near your computer with your hard drive,
or you may wipe out your data!  Also take that plastic box of floppies 
away from the area too!
>
>(The Voice of Experience Speaketh: When degaussing, bring ye not thy credit
>cards, ATM cards, etc., near to thy coil, or passeth thy coil near to thy
>wallet, lest ye be shunned by the Wizards of Electronic Finance forevermore!)

I'm forever a bit paranoid about demagnatizing my ATM card.  If I do, then
I can't get money out of the bank anymore (seem to remember some sort of
manual method of getting money from a human in the bank, but I can't 
remember how it is done. (-:  ).  We have lots of magnets holding stuff
on the metal walls of this place, luckly mostly not at wallet level.
============================================================================
I'm not going doun with the ship, no way!   < Scatterbrain
From: dshipley@cs.umr.edu (Dan Shipley)
Newsgroups: sci.electronics
Subject: Hex-FET's and infinite impedance
Date: 6 Apr 92 01:51:50 GMT

Hi, all!

I just got a car audio amplifier from Coustic.  In the manual, it says it  
uses hex-FET's and NOT to turn the amplifier on if there is no load on the  
outputs.

I don't know anything about hex-FET's, but it seems unusual that an infinite  
output impedance would cause damage to a transistor.  However, I'm always  
learning just how much I don't know, so if someone could enlighten me in the  
ways of hex-FET's or why this might cause damage, I'd be grateful.

Thanks in advance...

Dan
--
*****************************************************************************
   dshipley at cs.umr.edu
or r092592  at apollo.civil.umr.edu     (The University of Missouri - Rolla)
or dan      at ee.umr.edu                    UMR ... The BLACK HOLE !!!
***************************************************************************** 
!