HDTenEightyP/NetNews huggingface dataset:
From: dbell@cup.portal.com (David J Bell)
Newsgroups: sci.electronics
Subject: Re: uv watch
Date: Fri, 24 Jul 92 17:56:30 PDT
Organization: The Portal System (TM)
Distribution: na


>I'm sure I'm not crazy.  About four or five years ago I saw a 
>watch for sale that measured uv radiation--or so it claimed.
>I told some friends in the field this and was told I was
>crazy.  Does anyone know anything about this watch?  Does
>anyone have one?  Who is the manufacturer?  Are they still
>available?

>I have tried on my own to trace this down.  I've gone to the
>consumer electronic show here in Chicago, and got a major
>run around.  I've checked with several local stores to no
>avail.  Any recollections of this watch will help me.

>betsy@rainbow.uchicago.edu

Nope, you're not crazy. Well, not about *this* item, anyway!  :{)

I've seen the gadgets, too, but right now I'm not sure who
has them. I recall one that was a watch-like unit, and another
that was more like a cigarette pack-sized box. They both were
designed to measure and integrate UV-(A? B?) and signal after
a preset "dosage".  I remember prices in the $30-$40 range...

Dave
dbell@cup.portal.com
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
From: jsimon@rchland.vnet.ibm.com (Gerald Simon)
Subject: Re: Life after CDs
Date: Fri, 24 Jul 1992 20:37:24 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM Rochester

In article <1343@eouk9.eoe.co.uk>, ahaley@eoe.co.uk (Andrew Haley) writes:
|> smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:
|> : 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 
|> 
|> No, it's not apocryphal, but you've got a slightly distorted version.
|> The person was Akio Morita, not his wife, and one of his favourite
|> pieces is Beethoven's Ninth, which, if played fairly slowly, can be 74
|> minutes long. The Dutch engineers at Phlips supposedly wanted an
|> hour, which sounded like a nice round figure.
|> 
|> Incidentally, one of Morita's best friends was Leonard Bernstein.  I
|> wonder how long his recorded performances of the Ninth are.  Anyone
|> know?
|> 
|> Andrew.
 
This may sound stupid but, when I look at the back side of a CD (the side
the music is on), the light reflected back in the first part of the CD 
(usually less than 1/4 inch from the outside) differs from the light reflected
back from the rest of the CD.  I've always assumed that's the portion of the CD 
where the music is recorded.  If that assumption is correct, than there is 
a LOT of space left over for additional music over the rest of the CD....How 
wrong am I?

Jerry
Newsgroups: sci.electronics
From: tchannon@black.demon.co.uk (Tim Channon)
Subject: "Super-CD" ... soon ? 
Distribution: world
Organization: null
Date: Thu, 30 Jul 1992 23:40:39 +0000

>Amid the moans and groans of audiophiles and some musicians over the 
>less-than-perfect sound reproduced by digital methods (CDs in partic)
>I have been hearing of a new device that might put an end to the
>..
If 'at least 5 yrs' is soon!

We have not hit the limit of 16 bit linear PCM yet. The entire record and 
replay chain is nowhere near that yet.

Do you have any idea of what >90dB dynamic range really means?

Taking the upper limit as SPL of 110dB at which  you  will  suffer  permanent 
hearing damage if sustained and subtracting 90, you get SPL of 20dB.
Anyone care to give examples of SPL 20dB?

What is the dynamic range of a large orchestra?

  TC. 
    E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk
                                
Newsgroups: sci.electronics
From: johnh@macadammq.edu.au (John Haddy)
Subject: Re: SHOCKING STORIES
Organization: Macquarie University, School of Mathematics, Physics, Computing and Electronics
Date: Wed, 22 Jul 1992 05:51:48 GMT

In article <1992Jul18.175339.10396@newstand.syr.edu>, feliccia@rodan.acs.syr.edu (Nicholas J Feliccia) writes:
|> ..
|> 
|> Ok. I want to know from the net people. What is the largest voltage shock
|> you have ever received (and survived.) I am not talking about rewiring
|> a light switch. I am talking about kissing the flyback transformer.
|> 
|> Nick.
|> -------------------------------------------------------------------
|> feliccia@rodan.acs.syr.edu
|> N3FKS
|> 

Perhaps one shouldn't be bragging - it might prompt some bozo out there to try
and better the "record". Surely the largest shock _anyone_ has ever received
is already documented in the Guiness book of records: those few (extremely lucky)
people who have been hit by lightning and survived.

All that aside (:-), I did once accidentally touch both ends of a rheostat (one
end in each hand) that had 600Vdc across it. The result was a trip across the
lab, knocking several people to the floor on my way past. Or so I'm told - all
I remember is suddenly being 20 feet away from where I was before. Severe shock
set in about half an hour later (cold sweat, shivering, lack of muscle control
etc.) - not a nice experience and one which I'm not too keen to repeat.

----------------------------------------------------------------------------

      |  _  |_   _   |_|  _   _|  _|              Electronics Department
    |_| (_) | | | |  | | (_| (_| (_| \/           School of MPCE
    ---------------------------------/-           Macquarie University
                                                  Sydney, AUSTRALIA 2109

    Email: johnh@mpce.mq.edu.au, Ph: +61 2 805 8959, Fax: +61 2 805 8983

----------------------------------------------------------------------------
Newsgroups: sci.electronics
From: chuck@hans.mit.edu (Chuck Parsons)
Subject: Re: Green Layer on Circuit Boards?
News-Software: VAX/VMS VNEWS 1.4-b1  
Organization: MIT Lab for Nuclear Science
Date: Thu, 23 Jul 1992 18:16:00 GMT

In article <Brt82r.Kp@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spenc writes...
>In article <1992Jul22.183826.22771@csc.ti.com> jsykes@dadd.ti.com writes:
>>I could buy stuff in England that you just sprayed on the board immediatly
>>after tinning. You didn't need to mask out the solder pads - the film just
>>evaporated around the touch of a soldering iron...
> 
>That will be something different.  The main point of the green stuff --
>solder mask -- is that it *doesn't* go away at soldering temperature, so
>it keeps solder off things that shouldn't be soldered.
>-- 
>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

  The green solder mask I have applied before was epoxy with 
various aditives. Some brands were heat cured for an hour or two at about 
120C. Other brands were cured using UV light.

  Silkscreening it was a bitch, comparred to silkscreening cloth/paper
or metal panels which I have also done. Cloth and paper are absorbant
and any the ink/epoxy that seeps under the edges of the masked screen
is absorbed by the material on every pass.

 Compared to silkscreening metal panels it is hard because all the 
traces make the surface bumpy. It is particularly hard to get
the mask to go between to closely spaced traces that run in the
same direction that the silkscreening squegee is pulled.

  If you try it, a trick that helps is to put a piece of newspaper
over every board and silkscreen an image on the paper first, then
remove the paper and silkscreen the board. This keeps the underside
of the screen clean.

  Somebody, (Kodak I think) makes a solder mask film that can be
applied to the board and then photographically exposed, and developed.
It is more expensive than silkscreening but easier to learn.


regards, Chuck@pierre.mit.edu

Newsgroups: sci.electronics
From: gmw1@cunixa.cc.columbia.edu (Gabe M Wiener)
Subject: Re: Dolby B/C? (A??)
Reply-To: gmw1@cunixa.cc.columbia.edu (Gabe M Wiener)
Organization: Columbia University
Date: Thu, 23 Jul 1992 20:42:55 GMT

In article <1992Jul23.113150.7221@ohm.york.ac.uk> u9dmlb@ohm.york.ac.uk (Duncan McL Barclay) writes:
>on higher performance tape materials. Recently Dolby have
>brought out Dolby S again initally for the recording industry,
>this has lots of bands and is meant to provide a better SNR than
>digital systems. Dolby S is now available commerically.

One minor correction:  The commercial version is called Dolby SR and is
*very* expensive.  Two channels of Dolby SR go for several thousand 
dollars.  Dolby S is the consumer version of SR.


--
Gabe Wiener - Columbia Univ.     "This 'telephone' has too many shortcomings 
gmw1@cunixa.cc.columbia.edu       to be seriously considered as a means of 
N2GPZ in ham radio circles        communication. The device is inherently of
72355,1226 on CI$                 no value to us." -Western Union memo, 1877
Newsgroups: sci.electronics
From: medin@catbyte.NoSubdomain.NoDomain (Dave Medin)
Subject: Re: Coax Question
Reply-To: medin@catbyte.b30.ingr.com
Organization: Intergraph Corporation, Huntsville AL
Date: Mon, 27 Jul 1992 22:44:16 GMT

In article <1992Jul25.120158.600@cmkrnl.com>, jeh@cmkrnl.com writes:
|> 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!  

Just a few corrections...

Ethernet taps are TRUE current sources (ideally behaved like infinitely
high-value resistors), not voltage applied through a resistor. Otherwise,
they would screw up the impedance of the line and cause possible
reflections. The voltage produced on the line is that developed by the
current source flowing through the termination resistor alone (or
the immediate cable impedance--properly terminated coax behaves
like a resistor of its termination value). You're correct that
collisions are detected by an abnormal DC voltage on the line (a
negative voltage with respect to the shield due to how the current
sources are polarized).

The line is terminated at each end by 50 ohms to preserve the
characteristic impedance of the line and prevent reflections. The
net impedance to a signal entering the line is 25 ohms, as the signal
can flow either way, encountering a 50 ohm load in each direction.

The application notes of AMD's Ethernet transceiver chips are a great
tutorial for those wishing to learn more about the physical Ethernet
interface.

-- 
 --------------------------------------------------------------------
       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
From: kai@pangea.Stanford.EDU (Kai Lanz)
Subject: Magnetic tape developer
Organization: Stanford Univ. Earth Sciences
Date: Wed, 29 Jul 1992 22:49:20 GMT

Bob Butler (butler@vax.sonoma.edu) asked about a magnetic-tape developer
called Kyread...

The stuff I used to use was called MAG VIEW magnetic tape track developer.
It was (is?) made by Nortronics Co. Inc. of Minneapolis. It contains
(surprise!) iron powder and Freon (tm).

It worked great; unfortunately the propellant's used up in the little can
I have, and I don't know who distributes this stuff or if Nortronics still
exists. Anybody?

I also used to have a little disk-shaped magnetic viewer which could be
used to inspect mag tape, but the suspension liquid in the thing dried out
ages ago. It was made by 3M.

--- Kai Lanz         kai@pangea.stanford.edu

Xref: sparky sci.electronics:13602 rec.audio:11024 alt.folklore.urban:20078
From: manley@optilink.UUCP (Dave Manley)
Newsgroups: sci.electronics,rec.audio,alt.folklore.urban
Subject: CDs, Pens and Blue Lasers.
Keywords: Make MILLION$ with ME.
Date: 29 Jul 92 19:59:57 GMT
Organization: SONIC CLARITY(tm) CORP., LTD. Obik NJ.
Followups-To: sci.electronics,rec.audio,alt.folklore.urban,misc.test

I note that the SONY CORP. has aNNOUNCED the development
of a BLUE LASER.  It IS ANTICIPATED the new laser will
allow development of new CDS with TRIPLE THE CAPACITY
of current ONES.  In preparation for delivery  of this 
NEW technology I SEE A GREAT NEED for an AUDIOPHILE 
QUALITY PEN to guarantee ACCURATE RETRIVIAL of this 
data from the new format CD to insure SONIC CLARITY(tm).

If you are INTERESTED in becoming RICH WITH ME and
KNOW WHAT COLOR pen will be required please contact
me IMMEDIATELY.

reply in this newsgroup or to:

manley@sonic.com

or

+--------------------------------------------------------------+
+ PRESIDENT DAVID L. MANLEY PHD., CEO, CFO, CKO                +
+ SONIC CLARITY(tm) CORP., LTD.                                +
+ 1 AMBIANCE CIRCLE                                            +
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+ do not necessarily reflect the views of the SONIC CLARITY(tm)+
+ CORP., LTD.                                                  +
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+ SONIC CLARITY(tm) CORP., LTD. IS A FORWARD LOOKING FULL-LINE +
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+ Sister City to Trondheim Norway, and is a Nuclear Free Zone  +
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+ workplace and requires that all offers of employment         +
+ be contingent on satisfactory pre-employment drug test       +
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From: dny@humus.cs.huji.ac.il (Danny Halamish)
Newsgroups: sci.electronics
Subject: Re: Airport X-Rays
Date: 29 Jul 92 08:49:52 GMT
Organization: Indiana University

In article <4836@unixhub.SLAC.Stanford.EDU>, ralph@falcon.SLAC.Stanford.EDU (Ralph Becker-Szendy) writes:
|> 
|> And while we are asking for facts (which are a rare find on this
|> newsgroup): How about EPROMs and similar stored-charge memory devices?
|> After all, EPROMs are erased by UV, do they resist the airport X-ray
|> machine? I'd guess that the X-rays are heavily attenuated by the case
|> of the EPROM (the top of which is transparent to UV light but not to
|> X-rays), but is there real danger to EPROMs ?
|> 
A friend of mine just returned from taiwan with two 486 boards, with bios and 
all. Both have survived the X - rays.

I have had audio tapes X-rayed in airports several times and did not notice 
any differnce.

-- 

-Danny

dny@mossad.cs.huji.ac.il
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Date: Fri, 24 Jul 1992 18:51:01 GMT
Subject: Re: TV all opened but cannot find problem
Organization: Hewlett-Packard, Fort Collins, CO, USA
Newsgroups: sci.electronics

> You simply forgot the best way of electrocuting yourself with a TV set:
> the switched-mode power supply. Voltages aren't that big there... but the
> currents are! High voltage (25kV) is available at some milliamps only, but
> let's assume your body has a resistance of some kiloohms... You won't need
> very high voltages to get a lethal dose... just enough drive!
> 
> Chris.

Chris, what do you think constitutes "drive" in electrical terms, if not
voltage?

The HV supplies in TVs ARE hazardous - true, they are generally not capable
of supplying especially high currents for long durations - but the CRT itself
is a pretty good capacitor, and I can guarantee anyone coming in contact with
the CRT anode an unpleasant experience at best.

Actually, the "best way of electrocuting yourself" in TV work is probably
either coming in contact with the AC line, or with what's generally called
the "B+" voltage, usually around 90-120 VDC.  Other "potential" hazards (if
you'll ignore the pun) are the various supplies for the CRT "base"
connectors - the grids and focus voltages can be in the several hundred to
several thousand volt range.

One of the best practices in TV service is the old serviceman's trick of 
keeping one hand in your pocket at all times, when working on the set with the
power on (or with caps not yet discharged).  This will prevent a "two-handed"
contact, and so will prevent a current path through the heart.  (This is how
the "old servicemen" get to be old!)

In a more general comment: Yes, as is often stated here, it's the current
that kills, not the voltage.  A hundred microamps is sufficient to stop the
heart if applied directly to it.  But Mr. Ohm's legacy still holds true,
and you need enough electrical "pressure" - voltage - to pump the current
through a given resistance.  The resistance through the human body varies with
conditions (sweaty vs. dry skin, for example), and the path taken (hand to
hand, hand to leg, etc.), and so it is very difficult to say in advance, "This
is lethal.  This isn't."  In general, you're not going to have any problems
with, say, a 12V supply, no matter how much current the thing can put out.
(Remember that there are limits below which the safety folks consider you at
"Safety Extra Low Voltage" (SELV), and do not worry about you any more.)
Anything about 25-30 volts or so, treat with caution.  Note also that these
comments apply solely to *electrocution* - you can certainly have an unpleasant
experience with a 12V 250A supply by welding your watch band across the 
output terminals!


Bob Myers  KC0EW   Hewlett-Packard Co.      |Opinions expressed here are not
                   User Interface Tech. Div.|those of my employer or any other
myers@fc.hp.com    Fort Collins, Colorado   |sentient life-form on this planet.
Newsgroups: sci.electronics
From: pegasus@csd4.csd.uwm.edu (David R Hucke)
Subject: 8051 help needed urgently!
Originator: pegasus@csd4.csd.uwm.edu
Organization: Computing Services Division, University of Wisconsin - Milwaukee
Date: Thu, 30 Jul 1992 07:03:38 GMT


Hi everybody!

Well I finally got my 8051 compatible micro-controller in the mail
and got it all wired with a crystal and MAX232 chip and reset hardware.

I was able to invoke the onboard serial program load mode and load a
program on the chip...

The program simply set a bit on a port...

I had an LED hooked up to port 1 pin 1 with a resistor and connected to
ground like this:

               |
	       |  Port 1 Pin 1
	       |
	       LED
	       |
	       ^v^v^v  150 ohm resistor
		    |
	            |
		    GND

So my first program was this:

setb P1.1  ;; Set Port 1 Pin 1 to 1  

This turned on the LED as expected...

Now my second program was this:

clr P1.1  ;; Set Port 1 Pin 1 to 0

This should have turned off the LED.. It did not turn off the LED... In fact
nothing I do turns the LED off...

Anybody have any idea what is going wrong?

When I go into Serial Load mode (RST goes low) the LED still on also.

Any help would be appreciated...


-- 
pegasus@csd4.csd.uwm.edu                David R. Hucke
                                        UW-Milwaukee Film Major
--
Newsgroups: sci.electronics
From: martinn@mksol.dseg.ti.com (niels r martin)
Subject: Re: Green Layer on Circuit Boards?
Organization: Texas Instruments, Inc
Date: Wed, 22 Jul 1992 18:45:09 GMT

In article <BrsvB7.EzC@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>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

The 'green stuff' is properly termed "permanent solder mask".  Its primary purposes are twofold.  1) to allow for closer spacing of plated-through-holes (PTH) on the board (since via holes are masked off by the 'green stuff') and 2) to prevent solder (particularly during wave soldering) from entering the via holes.

-- 
________________________________________________________________________________Niels Martin				|                      
martinn@mksol.dseg.ti.com		|  AGM-88C  Get out of HARM's way!!
My opinions don't represent		|  10000+ on-time deliveries!
my employer's--but they're right!	|  Best Radar 'Detector' Around!
From: ting@mozart.amd.com (William Ting)
Newsgroups: sci.electronics
Subject: IBM PCjr IR keyboard pinout
Date: 24 Jul 92 13:09:42 GMT
Organization: AMD


Hi all,
		Does anyone has the pin out for IR receiver unit in the IBM PCjr? I would like to modify the receiver for my AT286 machine. Thanks!
	Please Email me your kind response! Thanks again...
ting@asahi.amd.com
From: rhenrie@emdeng.DaytonOH.NCR.COM (Roland.Henrie)
Newsgroups: sci.electronics
Subject: Telephone Signals
Date: 28 Jul 92 15:39:35 GMT
Reply-To: rhenrie@emdeng.UUCP (Roland.Henrie)
Distribution: na
Organization: NCR, E&M Dayton

What are the signals (ie. description,voltage swings,max. current) which
appear on standard residentail telephone lines?  My phone line has 4 lines
in it: black, red, green, yellow.  Please send responses via E-Mail.  Thanks,
Roland.
-- 
rhenrie@emdeng.DaytonOH.NCR.COM     ||   
NCR of AT&T - E&M Dayton            ||