HDTenEightyP/NetNews huggingface dataset:
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Green Layer on Circuit Boards?
Date: Wed, 22 Jul 1992 17:01:53 GMT
Organization: U of Toronto Zoology

In article <1992Jul21.134601.8985@cci632.cci.com> adw@cci632.cci.com (Allen Williams (co-op)) writes:
> However, one step that I think would be a good addition is the green
>layer of plastic insulation that commercial circuit boards have. I've looked
>in the Mouser and Digi-Key catalogs, and can't find anything that looks like
>the type of insulation that would go on top of the traces.

Look for "solder mask" or something similar.  In a bottle, not an envelope:
it's applied by a silk-screening process, and then (I would guess) baked on.

> Is it possible to add this layer of green insulation on do-it-yourself
>boards? ...

Shouldn't be hard, if you can sort out how to convert your pad pattern to
a silkscreen.  Silk-screening is a standard art/craft process.
-- 
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  henry@zoo.toronto.edu  utzoo!henry
From: tonyo@pendragon.CNA.TEK.COM (Tony Ozrelic)
Newsgroups: sci.electronics
Subject: Re: SHOCKING STORIES
Date: 22 Jul 92 20:35:45 GMT
Organization: Tektronix, Inc., Redmond,  OR.

OK, here's mine:

Tesla Coils:

Numerous RF burns as a result of 'experimenting', including one
whale of a shock due to directly connecting the bottom of the secondary coil
to the top of the primary and using a screwdriver to draw an arc from the
top of the secondary (my thumb was just a *leetle bit* too close to the
metal part of the 'driver).

Van de Graafs:

The Human Capacitor trick is neat (stand on an insulating
platform, grab top of VDG, hang on as long as you can) - if you don't
arc to anything, EVERYTHING repels everything - your shoelaces stand on end,
and when you spit, the saliva rips itself apart into a fine spray as it
leaves your mouth, then does a right-angle turn in midair as it zips over to
something grounded! My brother decided it would be fun to discharge
me by pulling a spark from my nose - it felt like somebody hit me in the face
with a tennis racket.

Accidents:

I built a brainwave detector (right out of PopTronics, during the
Biofeedback Era), and didn't have any 9V batteries to power it, so I used my
homebrew 15V power supply. Hookup, put the headgear on, try to detect
brainwaves, just hear 60Hz hum. Fool around with controls. Still no good.
Need to get to tweak some pot in the box, grab power supply to move it out of
the way - I grabbed the heatsink, which was hot with unregulated 15V, and the
middle of my forehead was grounded. What an experience! the entire world
did the same thing your TV set does to the picture when you turn it off -
everything shrinks and goes dim! I found that by adjusting the pressure of
my grip, I could cause the shrinking/dimming to vary. It scared the crap out
of me, and I never did get around to trying the thing out with batteries.

Another time I was working as a repair tech on seat boxes (the gizmos under
your airplane seat that pipe music to you - 12 channels of stereo, plus a
PA line for the pilot and an intercom, all time-division multiplexed onto
one wire, to save weight). The test fixture used 220V 3 phase 400Hz, 'cause
that's what the plane had on it, and I managed to get zapped. It felt like
somebody driving a red hot nail into the back of my hand! It hurt for hours
afterward.

Inquisitive Kids:

My oldest son (about two at the time) had discovered how to disconnect the
phone line from the phone. He was chomping on the end when I heard the extension
ring. The look on his face was beyond description. The phrase "go ballistic"
pales in comparison to his activities shortly thereafter.

My daughter tried the tweezers-in-the-socket trick and managed to vaporize
the tweezy part of the tweezers as well as the innards of the socket.
From: thad@public.BTR.COM (Thaddeus P. Floryan)
Newsgroups: sci.electronics
Subject: Re: SHOCKING STORIES
Date: 22 Jul 92 09:04:26 GMT
Organization: BTR Public Access UNIX, Mountain View CA

In article <1992Jul21.005244.27329@nuchat.sccsi.com> steve@nuchat.sccsi.com (Steve Nuchia) writes:
>[...]
>At age three I discovered that I could make the christmas tree
>lights blink by playing with the plug.  It was great fun until
>I got my finger across the contacts.  Three flips on the way
>out from behind the tree, if I counted properly :-)

That story reminded me of what happened to me about five years of age,
and should be a lesson for manufacturers of plugs.

I had needed to move a desk lamp from my Dad's desk to my room, so I
thought I'd simply unplug it, move it, and plug it in at the new location.

Simple, no?

Stupid plug was tapered THE WRONG WAY.  Thick part was at the wall, thin
end met the cord.  My tiny hands couldn't exert enough force to extricate
the plug, so I just pulled the cord ... right out of the plug.

So far so good.  But the damned plug was still in the socket on the wall.

"Aha," thought I, I'll just use my Dad's pipe reamer as a pry (since the
reamer was atop his desk).

Back-and-forth, back-and-forth, back-and-forth, plug was starting to loosen
its death grip on the socket.  Faster, faster, faster ... then I slipped and
fell forward (fortunately losing my grip on the reamer) at the same instant
the reamer contacted both prongs of the plug: *P*O*P* pht flit phtt phtt
sizzle.  Wow!  The most beautiful "spark" (more like miniature ball lightning)
was slowly arcing its way through the air onto the rug where it burned a small
hole.  Needless to say, the reamer was melted.  So was my behind after my Dad
found out what happened!  :-)

Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
Newsgroups: sci.electronics
From: jeffj@krfiny.uucp (J. Jonas)
Subject: Re: "Jacobs Ladder" - How do you make this project???
Summary: no shocking stories here
Organization: Jeff's house of computer pieces
Date: Tue, 21 Jul 1992 17:08:35 GMT

necessary disclaimer: high voltage is dangerous.
I've always kept a fair distance from the neon transformer while it's live,
thus you'll see no postings from me about "shocking stories" because
I have none. (1)

Back in high school, I found an old neon sign transformer (7,500 volts),
so I used an old TV "rabbit ears" for the ladder.
I mounted it on a wood base, but the sparks favored the bottom too much.
I cut a slot in the middle and inserted a glass plate,
thus forcing the spark higher on the rods.
The sparks were very satisfying - thick, white-blue and made
that wonderful zidding sound as they rose.

In a darkened room, I could see a glow all over the wires from
the transformer to the rods.  This on a bare wood floor!
That's when I realized that rubber insulation has very real limits,
and that power lines are really not insulated (the rubber coating
is not an insulator at such voltages).

In the movies, you'll notice that the jacob's ladder is usually inside
a glass tube.  This is probably for safety, as well as for
making it work better (eliminates wind/breezes and contains the ozone).

- Jeffrey Jonas
jeffj@synsys.uucp

(1) a good source of shocking stories is the "Hobie hotline" magazine.
Hobie cats are small (14-20 foot) catamarans.
Their aluminum masts are over 20 feet tall and are raised as the
sailboat is set up on the beach.
There are often power lines along the beach, thus the warning sticker
on every mast to watch for overhead power lines.
-- 
-- 
Jeffrey Jonas

jeffj@synsys.uucp
Newsgroups: sci.electronics
From: tchannon@black.demon.co.uk (Tim Channon)
Subject: Life after CDs 
Distribution: world
Organization: null
Date: Fri, 24 Jul 1992 20:05:00 +0000

> > > They [Sony] couldn't break themselves of thinking 12" - ala LP's or
> > > LDs.  I took Philips to come up with an under 5" disk.  And
> > > then Sony and Philips got together and standardized on the
> > > current 12cm disk that sped'ed out at 74 minutes.
> > > 
> >There is a story (probably apocryphal, anyone know?) that the 74 minutes
> >time was chosen because it was just long enough to hold the Sony MD's wife's>  favourite piece of classical music...
> >
> 
> The part I heard was that this requirement wasn't going to work at the
> designated sample rate of 48 KHz, so they cut it back to 44.1 to squeeze it
> in.
> 
No offence meant, but, stories are stories.

If you wonder why 44.1 was chosen, just think about how CD is mastered, the 
practicality of changing extant equipment etc. etc.

A lot of the design of CD goes back to availability of practical 
semiconductor lasers and their wavelength.

As ever compromise, compromise and what we have is in my opinion a very good 
one.

  TC. 
    E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk
                                
Newsgroups: sci.electronics
From: kludge@grissom.larc.nasa.gov ( Scott Dorsey)
Subject: Re: Source for magnetic tape
Organization: NASA Langley Research Center and Reptile Farm
Date: Mon, 27 Jul 1992 23:11:55 GMT

In article <1992Jul27.215413.10542@usenet.ins.cwru.edu> ar961@cleveland.Freenet.Edu (Duane Kaufman) writes:
>
>Hello!
>
>I was wondering if anyone knew of a source for bulk magnetic tape,
>(1/4", like used for computer data storage) I really only need the magnetic
>media itself, not the cassette.

What do you intend on doing with the tape?  Tape designed for digital recording
has a very different characteristic than tape intended for analogue use.  There
are different coercivities and grain sizes for different dynamic ranges and
frequency response.  Do you intend on using it on open reels or in some kind of
cartridge?  Do you want it backcoated or not?
--scott

(This all assumes you aren't using a helical scan system... you aren't, are
you?)
Newsgroups: sci.electronics
From: ar961@cleveland.Freenet.Edu (Duane Kaufman)
Subject: Source for magnetic tape
Reply-To: ar961@cleveland.Freenet.Edu (Duane Kaufman)
Organization: Case Western Reserve University, Cleveland, OH (USA)
Date: Mon, 27 Jul 92 21:54:13 GMT


Hello!

I was wondering if anyone knew of a source for bulk magnetic tape,
(1/4", like used for computer data storage) I really only need the magnetic
media itself, not the cassette.

Thanks in advance!

-- 
                                                     TheSeeker
Duane Kaufman
Internet: dkaufman@vms.macc.wisc.edu
BitNet:   dkaufman@wiscmacc.BitNet        I looked under chairs...
Xref: sparky sci.electronics:13166 rec.audio:10737 alt.folklore.computers:11000
From: smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC)
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
Subject: Re: Life after CDs
Date: 23 Jul 1992 13:53:23 GMT
Organization: SunConnect
Distribution: world
NNTP-Posting-Host: hardy.france.sun.com

In article <1992Jul23.041115.20377@bilver.uucp>, bill@bilver.uucp (Bill Vermillion) writes:

	> 
	> They [Sony] couldn't break themselves of thinking 12" - ala LP's or
	> LDs.  I took Philips to come up with an under 5" disk.  And
	> then Sony and Philips got together and standardized on the
	> current 12cm disk that sped'ed out at 74 minutes.
	> 
	> 
There is a story (probably apocryphal, anyone know?) that the 74 minutes
time was chosen because it was just long enough to hold the Sony MD's wife's favourite piece of classical music...

Steve 
Xref: sparky sci.electronics:13207 rec.audio:10755 alt.folklore.computers:11039
From: einari@rhi.hi.is (Einar Indridason)
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
Subject: Re: Life after CDs
Date: 23 Jul 92 20:55:15 GMT
Followup-To: sci.electronics

In <14mdkjINNb4m@grapevine.EBay.Sun.COM> smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:

>In article <1992Jul23.041115.20377@bilver.uucp>, bill@bilver.uucp (Bill Vermillion) writes:

>There is a story (probably apocryphal, anyone know?) that the 74 minutes
>time was chosen because it was just long enough to hold the Sony MD's wife's favourite piece of classical music...

I have heard that, and the classical music piece is supposed to be
Beethoven's 9th symphony.


-- 
einari@rhi.hi.is
Organization: Queen's University at Kingston
Date: Tuesday, 21 Jul 1992 17:03:53 EDT
From: <LEEK@QUCDN.QueensU.CA>
Newsgroups: sci.electronics
Subject: Questions about GAL .JED download file

I am in the process of building a GAL programmer from programming
specs I got from National Semiconductor.

(Unfortunately that's under non-disclosure, so I can't give the specs out.
Just in case someone asks.  It is a shame that the GAL manufacturers don't
make their programming specs available to the public.)

I have a few questions about the JEDEC file format used for downloading
fuse maps to programmer.  Is there a machine readible description of
the JEDEC format available from ftp ?

There are a few of the commands I can't figure out:
(All of these are found in Nation Semiconductor OPAL JR examples)

1)  QP20   <- Is it # of pins ?  (20 right ?)
2)  F0     <- No idea what this might be
3)  C6743  <- Is it the checksum (in Hex) ? How is it computed ?

Does anyone know whether or not the newer devices (22V10, 18V10 from
Lattice & others) have similar programming pins as their respective 20,
24 pin counterpart ?

Thanks in advance.

K. C. Lee
Elec. Eng. Grad. Student
Newsgroups: sci.electronics
From: gude@uniwa.uwa.edu.au (David J W Emrich)
Subject: Re: PC masks from a laser printer??
Organization: University of Western Australia
Date: Mon, 27 Jul 1992 15:05:03 GMT

MATGBB@LURE.LATROBE.EDU.AU (BYRNES,Graham) writes:

>Dear Knowledgeable ones,
>Up until now I have made my PCB's using donut and tape transfers on
>overhead proj film, exposing Electrolube +ve resist on the copper.
>However, as I have now entered the compuer age and bought a cheapy
>PCB CAD program, I need to produce masks from a laser printer.
>I tried the obvious (direct print on transparency), but the result
>was sufficiently porous that the copper looked like a 1/2 tone printers plate
>after etching. What should I do? I'm going to try inking over the printed
>bits on the mask, but that doesn't leave me a long way in front of the 
>stick on donut method.
>Thanks,
>Graham B

Graham, 
I have found much the same problem, as you did, with light contrast on
the transparency.  There are a couple of solutions, and I have tried
them both, with reasonable success.

Firstly, there is a special kind of laser printer "transparecny" that is
actually frosted in appearence, (it looks much like "proper" plotter
paper).  It is specifically desinged for photo-litho type work, and
laser printers, so it won't melt in the LP (big drag otherwise!).  I am
not sure where to get it, but a company that sells drafting/plotting
supplies would know.

THe second solution, involves laser printing on paper (gives much
denser plot) and then photocopying onto the transparency, with the
photocopier set at maximum darkness.  Some experimentation gives best
results for the photocopier used.

I have used the second method quite recently, to generate PCBs that were
used in a rack mounted cabinet, and the contact fingers, which were the
most critical part, came out AOK.  As I mentioned, I have not found
(mainly coz I haven't looked for it) the paper I mentioned in the first
solution, but I am assured that such things do exist.

Happy Etching

[dav]
aka  David Emrich
gude@uniwa.uwa.edu.au
Newsgroups: sci.electronics
From: eric@telebit.com (Eric Smith)
Subject: Re: Life after CDs
Organization: Telebit Corporation
	<ultima.712363459@mcl> <2478@tau-ceti.isc-br.com>
Date: 28 Jul 92 22:32:36

>>On 29 Jul 92 01:07:12 GMT, jimc@tau-ceti.isc-br.com (Jim Cathey) said:
> I thought intertrack delays were tripped by a delay code in one of the
> subcode fields, and that there isn't actually a huge run of zeros in the
> data fields. 

There is subcode information, but the samples for that delay are on the disk
and get played.  They may not be zeros.  It may just be very low level audio
(i.e., "silence").  On properly mastered disks, tracks can have a leadin with
negative time, or no leading with continuous or discontinuous sound.  On
improperly (IMHO) mastered disks, there may actually be an audible leadin.

Eric

Newsgroups: sci.electronics,comp.sys.ibm.pc.hardware
From: ron@bert.cs.byu.edu (Ron Snyder)
Subject: Re: Airport X-Rays
Organization: BYU Computer Science
Date: 24 Jul 92 15:49:50
	<1992Jul23.115038.5296@werple.pub.uu.oz.au>
	<1992Jul24.160242.6175@athena.cs.uga.edu>
	<14pecvINNn1a@darkstar.UCSC.EDU>


   Someone who travels often should do us all a favor and experiment. Pack
   360K, 1.2M and 1.4M disks with data (one big ZIP file, perhaps) and put
   them in the luggage that will be X-rayed. Trying to unZIP the file will
   reveal if any of the data has been corrupted. If several people do this
   in several airports (a variety of X-Ray equipment) and post the results,
   we'll all know for sure.

I'll do this, but you'll have to wait until the end of September to find
out the results.  :)

--
Ron Snyder <ron@bert.cs.byu.edu>   <snyderrj@coned1.byu.edu>
****************************************************************
Newsgroups: sci.electronics
From: medin@catbyte.NoSubdomain.NoDomain (Dave Medin)
Subject: Re: Replacing LCD for a Temperature sensor
Reply-To: medin@catbyte.b30.ingr.com
Organization: Intergraph Corporation, Huntsville AL
Date: Tue, 28 Jul 1992 17:00:27 GMT

In article <1992Jul28.141433.6425@linus.mitre.org>, rajiv@hilltop.mitre.org (Rajiv Kohli) writes:
|> I am not an electronics engineer but do play around with gadgets
|> 
|> I have a temperature sensor from SEARS with LCD display. It gives
|> the inside outside temperature. 
|> 
|> Q:	The LCD display is large and I was trying to see if a
|> 	small size one is available from the market and if anyone can
|> 	suggest replacing methodology. I wouldn't mind a LED display,
|> 	infact, would prefer it. I am trying to fit it in a small
|> 	box in the dash board so it merges into the standard
|> 	setting of the car.

Why not use the Radio Shack LCD temperature display module
(part number 277-123). It is self-contained and already
miniaturized. It even has a temperature alarm threshhold
so it could be used to alert you, for example, when the
temps are close to 32 (ice on bridge surfaces, etc.)

-- 
 --------------------------------------------------------------------
       Dave Medin			Phone:	(205) 730-3169 (w)
    Intergraph Corp.				(205) 837-1174 (h)
       M/S GD3004
  Huntsville, AL 35894 		Internet: medin@catbyte.b30.ingr.com
				UUCP:  ...uunet!ingr!b30!catbyte!medin

   ******* Everywhere You Look (at least around my office) *******

 * The opinions expressed here are mine (or those of my machine)
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
From: sorin@techunix.technion.ac.il (Goldenberg Sorin)
Subject: Re: Life after CDs
Reply-To: sorin@techunix.technion.ac.il (Goldenberg Sorin)
Organization: Technion, Israel Inst. of Technology
Date: Mon, 27 Jul 1992 09:23:28 GMT

Somehow the cd manufacturers seem to squeeze more music into the c.d.
I have Mahler 2.nd with Klemperer - above 79 min.
From: bender@oobleck (Duke of Canterbury)
Newsgroups: sci.electronics
Subject: Re: White noise generator.....
Date: 28 Jul 1992 08:28:19 GMT
Organization: SPARK's R US
Reply-To: bender@oobleck.eng.sun.com
NNTP-Posting-Host: oobleck
X-Newsreader: Tin 1.1 PL3

John Hull writes...

: I'm one of those people who has to have some "white noise" in the background
: to sleep.  Something like a fan, or rain on the roof, or wind in the trees,
: something like that.
: 
: [my device that I use at home is big and bulky and] trying to carry it on a
: camping trip or on quick out-of-town trips is a drag.  Some motels have room
: air conditions which serve the purpose, but not always.
:
: Anyway...finally....it seems to me that if there is a sound-generator chip
: available, that a little portable unit could be made, which would run on
: ni-cad batteries (so that it could be recharged), with a small speaker such
: as is found in a cheap transistor radio.
		   ^^^^^^^^^^^^^^^^^^^^^^
I think that you may have answered your own question - if you can live with
the simple white noise produced by FM interstation hiss, you could buy a
small, cheap FM transistor radio and use that on your trips.

mike

--
The IQ requirement for being a phone operator may be pretty low, but the
required IQ for placing a call is just about vegetable level.  That's why
they kill sardines before canning them; if you let them swim around in the
can, it would heat up and explode.
From: jeh@cmkrnl.com
Newsgroups: sci.electronics
Subject: Re: Coax Question
Date: 25 Jul 92 19:01:58 GMT
Organization: Kernel Mode Consulting, San Diego, CA

In article <1992Jul22.052519.901@athena.cs.uga.edu>,
 mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
> [very nice explanation of "reflections" due to impedance mismatches]
> That's why we terminate Ethernet cables with resistors.  It prevents
> reflections.

well, yes, and this is important when the cable is "long".  But there's another
reason.  The resistors (or equivalents) must also be there with arbitrarily
short Ethernet cables, since the "carrier" on Ethernet is merely voltage
applied through a resistor.  The 25 ohms (net) resistance to ground seen by the
transceiver (50 ohms at each end) forms the other half of a voltage divider. If
two transceivers try to transmit at the same time the voltage on the cable is
higher than would be expected with just one transmitter -- and that's how
collisions are detected.  

Hence, very short (a few meters) Ethernets will work just fine with a 25-ohm
resistor at one end!  

	--- 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
Newsgroups: sci.electronics
From: rusty@masc.rice.edu ( Robert Kelley)
Subject: Re: 0.100" spacing
Organization: Dept. of Math. Sciences, Rice University
Date: Fri, 24 Jul 1992 18:50:56 GMT
From: mcorbin@oucsace.cs.ohiou.edu (Max Corbin)
Newsgroups: sci.electronics
Subject: Re: SHOCKING STORIES
Date: 21 Jul 92 18:52:16 GMT
Organization: Ohio University CS Dept,. Athens


Well I couldn't pass this one up.

In high school power mechanics class someone brought up the question...

"If everybody forms a line, will everybody get shocked by the spark plug
wire?"

My teachers response was  "Lets find out."

Lucky me I was the guy at the end acting as ground.  It did hurt quite a
bit, but it was worth watching everybodies arms go flying straight up into
the air :)


I also seem to remeber cleaning a spark plug cable on a minibike when
a little kid walked over and said "Maybe it works now!".  He proceeded
to pull the starter cord, and I proceeded to see little stars everwhere.

-- 
+-----+---\ +-----+ 	O O 	Beware the light at the end of the
| | | | -- >|  ---+	 +	tunnel.  It may be an oncoming Dragon.
+-+-+-+---/ +-----+     \_/
   M   	 D     C	 U      mcorbin@oucsace.cs.ohiou.edu
Newsgroups: sci.electronics
From: jonas@world.std.com (Jonas R Klein)
Subject: Re: Life after CDs
Organization: The World Public Access UNIX, Brookline, MA
Date: Fri, 31 Jul 1992 03:31:27 GMT

In article <1992Jul30.164545.10449@ole.cdac.com> ssave@ole.cdac.com (Shailendra Save) writes:

>   Thanks all for the reply (replies).  Is it possible to have the same CLV
>for magnetic discs?  (as in the hard disks of computers?)  Would have an interesting
>algorithm for sector mapping, but it should work, wouldn't you think?
>
>
>-Shailendra
>ssave@ole.cdac.com

As far as I know, Mac floppy disks use this method.  However, there would
be no way to vary the peed of a hard disk fast enough to keep up with the
position of the heads.  Drives take a few seconds to spin up to speed,
but only, say, 20 millisecs to move the head to the other side of the platter.

















-- 

____________________________          ______________________
    |                                |                      |
    |   +Jonas Klein                 |  "Place clever       |
Newsgroups: sci.electronics