HDTenEightyP/NetNews huggingface dataset:
From: kolks@imec.be (Tilman Kolks)
Newsgroups: sci.electronics
Subject: How do anti-theft systems in Shops work ???
Keywords: security shops theft
Date: 14 Apr 92 16:31:58 GMT
Organization: IMEC vzw, 3030 Leuven, Belgium

Hi folks:

I was wondering how in the world the anti-theft systems
work in shops. They look as follows:
At the exit, there are two parallel boards, standing up.
A person leaving the shop/library always has to pass *between*
these boards. The boards are attached to electronic stuff.
Articles bought in the shop are for example (in case of books)
'rubbed' over a plate. In case this hasn't been done properly,
or NOT at all (theft !), the alarm goes off when passing through
the gate.
When not concerning a shop selling books but other articles, like
CD's, the same anit-theft system is installed. People suggested to me
that in that case, something is attached to the article under the price-label.

How in God's name can this work ??
Electrical Field ? Magnetic Field ?
Space-vibes ?

If one of the first two is used, shouldn't it be a very strong field,
for such a great distance between the boards ?
And how about deviations by human-tissue, a watch, a belt etc. etc.

Could someone enlighten me ? I am feeling stupid here ...

Send for instance an Email. In case of THE answer, I'll post it ..
My mail-adres is : kolks@imec.be

Thanks


Tilman Kolks at:
	Imec,
	Kapeldreef 75,
	B-3001 , Leuven
	Belgium
	Email: kolks@imec.be
From: pdejong@fwi.uva.nl (Paul Gerard de Jong)
Newsgroups: sci.electronics
Subject: Re: *** Thermal sensor needed.
Date: 10 Apr 92 06:15:52 GMT
Organization: FWI, University of Amsterdam

afpauls@lims01.lerc.nasa.gov (PAUL SCHWARTZ) writes:

>My suggestion is to install thermocouples on each wing and connect the in 
>opposition (reverse series) so the two minus leads on the thermocouples 
>are connected together.  The voltage across the two positive leads would be 
>proprotional to the temperature difference between the wing tips.  The 
>polarity would indicate which wing is warmer.  A high gain amplifier driving 
>a analog meter might work very well.  The only thing I'm not sure about is
>if the thremocouples would respond fast enough to temperatures to make the 
>system useful.

You can get small thermocouples with timeconstants close to a second, so that
would be no problem. Type K thermocouples are 40uV/C (22 uV/F), so you 
would need to amplify about a factor 1000 to drive some analog meter, or LCD
DVM.

Bart.
From: richard.hsieh@Sun.COM (Richard Hsieh)
Newsgroups: sci.electronics
Subject: -- how does remote/universal remote works --
Date: 9 Apr 92 21:50:49 GMT
Reply-To: richard.hsieh@sun.com
Organization: Super Sparc Entertainment Systems (SSEC) Inc.
NNTP-Posting-Host: gismo.corp.sun.com

Hi,

This could be a stupid question, but what the hack. :-)

How does remote control works? If universal remote can learn other remotes'
signal, is there any "protocol" associated with it (sorry, i'm a networking
guy, like the word "protocol" a lot), at least, what is the agreed spectrum?
If there is, where can I find the "protocol" in printing?

Does venders have their own "id" in front of every IR beaming? I have 5 remotes,
more than 100 keys, always wonder how they can never interference with each 
other.

How about garage door openner, thermostat, water heater. those remotes doesn't 
seems to be IR beaming as we can find in consumer electronics. How can venders
preventing their heater won't be turn on by someone else's grage door openner?

Help the much confused soul, will ya?!

-- 
richard hsieh                     |                                        
1.415.688.9079                    |    Too bad, I can only speak for myself.
hsieh@gismo.Corp.sun.com          |
--
From: rcain@netcom.com (Robert Cain)
Newsgroups: sci.electronics
Subject: Re: Looking for Z80 development PCBs
Date: 15 Apr 92 06:24:11 GMT
Article-I.D.: netcom.ysyj-w_.rcain
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

Phil, while it doesn't *quite* fit your budget, Zilog makes a real fine
evaluation board for their Z84C15 chip which is a Z80 with 2 serial, 2
parallel, timers, two chip selects, and more.  The board comes with a rom
monitor and the software tools to do assembly level programming and debug
through one of the serial ports.  It has a header that exactly matches the
pinout of the chip for "in circuit emulation".  It costs $275 and has an
8kx8 sram on board.  The software tools are for a PC and downloads and debugs
through one of your com ports.  A real nifty little package.  The part
number for the kit is Z84C1500ZC0 and is available from any Zilog
distributer.  I got mine from Hall-Mark.  After CA tax and shipping the
grand total was $303.94
-- 
Bob Cain    rcain@netcom.com   408-358-2007

"There are some strings.  They're just not attached."
                                                    Victoria Roberts
From: bill@hacktic.nl (Bill Squire)
Newsgroups: sci.electronics
Subject: Re: Stereo FM demodulation question
Date: 8 Apr 92 22:13:07 GMT

klg@mc.duke.edu (Kim Greer -- rjj @ Duke Medical Center - Radiology) once wrote....
>In article <202-PCNews-120beta@hacktic.nl+ bill@hacktic.nl (Bill Squire) writes:

>  Would someone (Bill?)  mind giving an explanation of deemphasis, how it is
>done, the reason for doing it, what is done the the signal, etc.?  Thanks.

        To cut down on noise the high frequencies are increased at a rate
of 6dB/octave above the corner frequency defined by the pre-emphasis.  The
other side use de-emphasis which does the oposite.  FM in the states uses
75uS, Europe uses 50uS and what used to be the Soviet Union uses 100uS.
The SCA in USA uses 150uS.  The definition is simply R X C.  75k and 1.0nF
would define "75uS" and 150k and 1.0nF would define "150uS" for example.
For de-emphasis its just a first order LPF....a simple R/C circuit!  The
3dB corner is ofcourse 1/2pi RC.

                                                        Bill
From: jgk@cbnewsc.cb.att.com (joseph.g.klinger)
Newsgroups: sci.electronics
Subject: PADS Demo needed
Date: 16 Apr 92 18:26:53 GMT
Distribution: usa
Organization: AT&T

I must have called the factory about a month ago and still no demo disc.
Does anyone have an open-to-the-public modem number?
I'm anxious to a copy after the good reviews here on the net.

Are there any other PCB layout programs available for under $500.
I just need two sided boards with gerber output files.

Thanks,
Joe Klinger

-- 
	Joe Klinger
	att!iexist!jgk

Disclaimer - AT&T may not aggree with the opinions expressed in my comments.
From: CCEB001@UTXVM.CC.UTEXAS.EDU
Newsgroups: sci.electronics
Subject: Re: Sorting System
Date: 8 Apr 92 16:49:09 GMT
Organization: THE UNIVERSITY OF TEXAS AT AUSTIN

When The US mint went to laminated metal coins with no silver content they
wanted to reclaim the silver bearing coins before the silver hoarders
could.  They built a device to fire coins at a marble block, listen to the
ring with a microphone, classify the ring as clad, silver, or indeterminate,
then deflect the coin into the correct bin with a magnetic field.  Although
the coins were non magnetic the eddy cuurent in the moving coin would react
sufficiently with the field to do the job.  The indeterminate bin was run
through the machine again.  If your washers are as uniform as coins, the
magnetic field alone would be sufficient to sort the coins.

I thought you might be interested to see a real solution to a very similar
problem.  If you ever wondered why the silver coins dissappeared so quickly,
now you know.

Mike.Coyne@utxvm.cc.utexas.edu
From: dac@dacami.UUCP (David Culberson)
Newsgroups: sci.electronics
Subject: 120v 60Hz to 240v 50Hz?
Distribution: world
Date: 15 Apr 92 11:25:07 EST
Organization: Culberson Plaza.  (One Marconi Place, Inc.)

  Is it possible to run a printer I have that requires 240v 50Hz off of
120v 60Hz, uusing an adapter?  It's 150 watts.  How much would such an
adaptor cost?  Where is a good place to get them?  Thank you!

		-David

--
( dac@dacami.UUCP - cis.ohio-state.edu!n8emr!bluemoon!dacami!dac ) Amiga//
( - David Culberson - )  ( - Now living in Culberson Plaza! - )       \X/
Newsgroups: sci.electronics
From: ce3wa3bc@maccs.dcss.mcmaster.ca (Tom Nosella)
Subject: oscilloscope manual needed
Organization: Department of Computer Science, McMaster University
Date: Tue, 7 Apr 1992 07:37:38 GMT

I am wondering if some 
one can help me?  I bought 2 oscilloscopes used from the university i attend, but there werent any manuals with them.  They are the same scope , namely Tektronics modem RM-503 rackmount scopes.  I am desperately trying to find a manual for them, i called Tektronics, but they were unable to help me find one.  If anyone could suggest where i look, or someone may have one lying around that i could pay for a copy of, please let me know.  I need a manual to service these machines.
Please direct replies to me at ce3wa3bc@maccs.dcss.mcmaster.ca
Thank you very much.

Newsgroups: sci.electronics
From: interpol@casbah.acns.nwu.edu (Interpol)
Subject: Re: How to ease drop on cord-less phones.
Organization: Northwestern University, Evanston, Illinois
Date: Mon, 6 Apr 1992 17:44:05 GMT

In article <sehari.702511268@vincent1.iastate.edu> sehari@iastate.edu (Babak Sehari) writes:
>---
>My friend have a AT&T cord-less phone. Once, when I was playing with a receiver
>to search for odd frequencies, I picked up his phone conversation at 15.2MHz.
>With a little bit of hacking around I found that It was the second harmonic,
>that I was receiving.  The original frequency is 7.51MHz.  It was modulated 
>with the AM format.
>
>I thought this information might be useful for electronic hackers; therefore,
>I decided to share it with you.
>

Actually, what you probably heard was the image.  The actual frequencies for
cordless phones are, as allocated by the FCC:

Base:			Handset:

46.61 MHz		49.67 MHz
46.63			49.77
46.67			49.83
46.71			49.845
46.73			49.86
46.77			49.875
46.83			49.89
46.87			49.93
46.93			49.97
46.97			49.99

----------------------------------------------------------------------------
| Drew S. Cheng, BA '91 MD '95           | "Compelling, yet tedious...I    |
| Northwestern University                |  feel spent, like a man who is  |
|  Medical School, Chicago, IL USA       |  forced to wear his genitals    |
| Internet : interpol@nwu.edu            |  like a pendant."               |
|                                        |    - Dieter, "Sprockets"        |
----------------------------------------------------------------------------
From: bill@hacktic.nl (Bill Squire)
Newsgroups: sci.electronics
Subject: Re: How to ease drop on cord-less phones.
Date: 6 Apr 92 09:54:19 GMT

sehari@iastate.edu (Babak Sehari @ Iowa State University of Science and Technology, Ames, Iowa.) once wrote....
>---
>My friend have a AT&T cord-less phone. Once, when I was playing with a receiver
>to search for odd frequencies, I picked up his phone conversation at 15.2MHz.
>With a little bit of hacking around I found that It was the second harmonic,
>that I was receiving.  The original frequency is 7.51MHz.  It was modulated 
>with the AM format.

        The frequency probably is more like 46MHz and you picked up the
fund. which is mult. times 6 to reach the final output freq.  The AM was
probably incidental AM.  All cordless phones I've listened to have been FM
and all the modern ones either operate in the 46/49MHz bands or 900MHz
band.  There is also a new international allocation in the 1.6Ghz band, but
I know of none that operate there, due to the difficulty of producing that
frequency at very low cost, but it shouldn't be long until it is used!  The
earliest ones were base at about 1.8MHz and handset at about 49.9MHz.  The
1.8MHz FM frequency was never authorised by any government, but made design
easy, since it was far from the 49MHz frequency.  Often these units put out
over a quarter watt(which was supposed to be carrier current on the AC
wires in the home.  A Canadian Radio General team once went in the Yukon
on a Winter night and loged "hundreds" of cordless phones from Southern
Canada and the Northern USA.  Not very private at all!

                                                Bill
Organization: Masters student, Information Networking Institute, Carnegie Mellon, Pittsburgh, PA
Newsgroups: sci.electronics
Date: Tue,  7 Apr 1992 23:56:00 -0400 
From: Luis J Mendez <lm2k+@andrew.cmu.edu>
Subject: Survey

	Sorry for the waste of bandwidth...
	My name is Luis Mendez, student  at the Information Networking
Institute at Carnegie Mellon and I am working on a survey for an
Industrial Administration course.  The purpose of the survey is to
collect information regarding the characteristics that industrial
customers look for in a firm from which they plan to buy a product or
service and how those characteristics affect the selection process.  As
area of study, I have chosen computer hardware firms.  It is of my
interest to learn what characteristics are considered by corporations
when deciding from which firm it is desirable to buy computer hardware. 
If any of this netnews' readers is related to hardware purchasing at any
company and would like to participate on this survey, please send me an
email with a fax number where I can reach you, and I will fax you back
the questions and all the information concerning the survey.  Any help
you can bring me  will be really appreciated.  Copies of the team's
final report will be available upon request.  Thanks for your help.

	Luis Mendez
	lm2k@andrew.cmu.edu
From: bender@oobleck.Eng.Sun.COM
Newsgroups: sci.electronics
Subject: Re: Timing, A/D, and LCD Displays
Keywords: circuits a/d timing
Date: 7 Apr 92 21:09:28 GMT
Organization: Sun Microsystems, Mt. View, Ca.
NNTP-Posting-Host: oobleck

In article <Apr.7.14.33.55.1992.10465@caip.rutgers.edu> froncio@caip.rutgers.edu (Andy Froncioni) writes:
->I am planning on building a very very small circuit board that
->will fit on the steering wheel of a race kart.  I would like to
->implement several functions:
->
->
->I am looking for IC's that will perform as many of these functions
->as possible with as few external components as possible.  

You could use a microcontroller in the 8051 or 6809 family that has some
on-board A/D as well as on-board LCD drivers; these microcontrollers are
designed for these types of applications.  You would then shift your design
efforts to software to provide the features and the accuracy that you want.
I used to write instrument cluster code for a major automobile manufacturer
back in the early 80's; we used 8048's, 8051's, 6805's and some 4-bit
controllers.  Writing code for a tach/speedo is easy - writing code for a
GOOD tach/speedo that doesn't jitter and corresponds to the cruise control
is hard.

mike
--

                                coffee, anyone?
Newsgroups: sci.electronics
From: walter@ee.ubc.ca (Walter Wohlmuth)
Subject: UV detectors
Organization: University of BC, Electrical Engineering
Distribution: sci.electronics
Date: Thu, 9 Apr 1992 18:00:39 GMT

	I am looking for a photoconductive cell which will unable be
to detect UV radiation, 200-400 nm.  Cost needs to be under $10, around
1 M "on", 50 M "off", peak spectral response in the range specified.
If there are such devices made can someone tell me the part # and
distributor.  If no such devices exist, I will simply use a UV filter in front
of a photoconductive cell.  Could someone suggest the best photoconductive 
cell that can be used with the filter, ie: best spectral response.  I believe
that CdS cells can accomplish this task but I am unable to find a distributor
who sells these devices.  The product has been discontinued by a number of 
suppliers.

I need this device by Sunday, April 11.  

Thanx Walter A. Wohlmuth
From: jgk@cbnewsc.cb.att.com (joseph.g.klinger)
Newsgroups: sci.electronics
Subject: PADS Demo needed (with .sig this time)
Date: 16 Apr 92 18:42:14 GMT
Distribution: usa
Organization: AT&T

I must have sent for a demo copy of PADS about a month ago and still no
sign of it.  Does anyone know of an open-to-the-public modem number where
I can get a copy? 

Any other layout programs under $500 that can do two sided boards with Gerber
out files?

Thanks,

Joe Klinger
jgk@iexist.att.com

-- 
	Joe Klinger
	att!iexist!jgk

Disclaimer - AT&T may not aggree with the opinions expressed in my comments.
From: ldstern@rodan.acs.syr.edu (Larry Stern)
Newsgroups: sci.electronics
Subject: Need help with Sony TV remote control
Date: 11 Apr 92 05:01:24 GMT
Organization: Syracuse University, Syracuse, NY

To all: a neighbor of mine has a 6-7 year old Sony Trinitron, which works
well except for the remote control. The remote had an intermittent problem
where it would work fine for a few weeks, not work at all for a few days,
start working ok again, etc. It seems it is now, finally, dead. There is
one IC, a crystal, a few resistors and caps, and an LED inside. My question
is, what usually goes? Is this worth fixing? And finally, can this LED be
tested with an ohmeter like a "regular" diode?

Any help would be greatly appreciated.

						TIA, Larry Stern

--

Larry Stern                                  LDSTERN@RODAN.ACS.SYR.EDU
Newsgroups: sci.electronics
From: mzenier@polari.com
Subject: Old Colony Sound Lab (was Re: goodbye Heathkits_
Organization: Seattle Online Public Access Unix (206) 328-4944
Distribution: na
Date: Tue, 7 Apr 1992 19:18:30 GMT

In article <6178@public.BTR.COM> thad@public.BTR.COM (Thaddeus P. Floryan) writes:
>
>Though I've built more than a fair share of Heathkits over the years, I've
>also enjoyed the (almost raw) kits from Old Colony (the kit (mostly parts))
>operation of The Audio Amateur and Speaker Builder publications.
>Does anyone know if they're still around?  ...
>They had a companion "Computer Smythe" publication (also with kits)...

Computer Smyth ceased to exist about the time Circuit Celler Ink
came into existence.  But the Old Colony/Audio Amateur started publishing
the US edition of Elektor Electronics.  As part of that package they sell
circuit boards, proms, diskettes.  Elektor is a Netherlands based magazine
with their own development lab, and about a dozen different international
editions.  Some folks think it's too simple, some think it's too complex.  
It is interesting to see the european side of things.  But the parts lists
can be frustrating.

Old Colony Sound Lab
PO Box 243
Peterborough, NH  03458
(603) 924-6371  Visa/Mc

Elektor Electronics USA
PO Box 876
Peterborough, NH  03458
(603) 924-9464  Visa/Mc

Fax (for both) (603) 924-9467

Mark Zenier  markz@ssc.wa.com  mzenier@polari.com

Newsgroups: sci.electronics
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Tri State TTL
Date: Sun, 12 Apr 1992 03:19:50 GMT
Organization: U of Toronto Zoology

In article <1992Apr5.215721.11408@willamette.edu> agulhati@willamette.edu (Ashish Gulhati) writes:
>Relays switch the interface from one power suppply to the other as needed.
>Tri-state drivers from each power supply drive the interface...
>... going to either damage the tri-state devices or make them introduce
>noise into the system? Or is the connection to them literally an open circuit
>that I can forget about once I've disabled them? 

The connection is an open circuit with one exception:  you still have to
observe the limits on voltages that can appear on those pins.  If the two
power supplies are far enough apart that signals from one side go outside
the voltage limits on the other side's (disabled) tri-state devices, those
devices can be damaged.  Perhaps enough to ruin them, perhaps just enough
to make the system unreliable.  Those limits are not very wide; tri-state
devices aren't meant for this kind of thing.
-- 
GCC 2.0 is to C as SVR4 is to Unix.     | Henry Spencer @ U of Toronto Zoology
                             -Dick Dunn |  henry@zoo.toronto.edu  utzoo!henry
From: bill@hacktic.nl (Bill Squire)
Newsgroups: sci.electronics
Subject: Re: Telephone line Question
Date: 8 Apr 92 21:58:00 GMT


        Niether way you mention is "right".  Oh well try this:  Take an
opto-isolator like a 4N35 a diode to connect so it conducts when the LED
doesn't, and place a 4.7k resistor and a neon (NE-2) in series with your
protected opto led.  You know what to do with the transistor don't you?

                                                Bill
From: ferrick@acsu.buffalo.edu (Patrick K. Ferrick)
Newsgroups: sci.electronics
Subject: Can anyone identify this motor?
Date: 16 Apr 92 19:19:38 GMT
Organization: UB


I have a couple of motors that I'd really like to use, except
that I'm having some trouble figuring out how they need to be
hooked up.  Could someone out there please email me if you
can shed some light on this problem?

The motors are about 2" in diameter, 2" long, and were made
by Kearfott.  The sides bear the following diagram:	


    Frequency 400 cycles

  ___  Phase 1 115V ___
 |                     |
 |                     |
[1]        [2]        [3]
            |__________________

                               Phase 2
                               115V	
[6]        [5]        [4]______	
 |__________|           


I am fairly sure that the problem is in the 400 cycle bit,
the two phases, or both...but I'm not at all sure if I can
do anything about it!  I'd really appreciate any assistance
I can get...please reply via email if you wouldn't mind, as
I already subscribe to more newsgroups than I probably should!

Thanks,
pat
  
Newsgroups: sci.electronics
From: pollock@milton.u.washington.edu (Joe Pollock)
Subject: Re: DC Shock
Organization: The Evergreen State College
Date: Mon, 13 Apr 1992 06:55:33 GMT

For those of you unfamiliar with the "Invisible Fence(tm)" system, the
owner doesn't just strap on a shock collar and turn the dog loose in
the yard.  The collar  is a receiver sensitive to pulsed currents sent
through a wire loop at the perimeter of the yard.  The collar beeps
about six feet from the wire, and does not deliver a shock until the
animal is about three feet from the wire.

There is an extensive training regime the owner must  put the animal
through: it involves a white cord inside the perimeter to mark it for
the animal, and several weeks of training, where the owner walks the
dog near the wire on a lead and issues appropriate commands.  The goal
is to train the dog to the perimeter and to the beep, not to the shock.

My experience with this has been with a friend's dogs, which I occasionally
care for when he vacations, etc.  The dogs have absolutely no apparent
adversion to the collars.  They will stay inside the perimeter even if
the fence is off (we had an awful time finding a break in the 1500' of
wire one week - I finally built an audio detector to trace the loop), 
and know that if they are not wearing the collars it's OK to cross
the perimeter.  Yet, even if they are chasing a ball, they halt before
the collar even beeps.  The training is the key to the process -
the dogs will otherwise learn to make a running leap.

The system is expensive, however...

--joe pollock     pollock@u.washington.edu


Newsgroups: sci.electronics
From: ggjns@knuth.mtsu.edu (John N. Schmidt)
Subject: WANTED: IBM PC-Jr schematics for power supply, 5.25" FD
Summary: Schematic(s) needed, or a source for them (and costs?)
Organization: Dept. of CS, Middle TN State Univ, Murfreesboro, TN
Distribution: na
Date: Wed, 8 Apr 1992 07:37:59 GMT

I was recently given a PC-Jr which has an intermittent fault keeping it
from cold-booting or going through the Power-On-Self-Test *if* the 360K
5.25" floppy disk was connected to the power supply (through a black
4-conductor wire).  I am seeking a schematic of the PC-Jr in order to
determine expected voltages at the various test points, etc.  

Does anyone have such a schematic, or can point a source out to me?  Any
relevant costs, if known, would also be enlightening.  Replies via
E-mail or the Newsgroup are welcomed either way.  Thanks in advance! 
-- 
John N Schmidt KD4EAI, Lab Director | 615-898-5561 M-F 1300-2230Z <7-4:30>
Middle Tennessee State University   | 615-898-5538 or 896-2871 FAX 24H 
1500 Greenland Drive, PO Box 135    | ggjns@mtsu.edu <Internet Address>  
Murfreesboro, TN  37132-0135 USA    | MTSU Center for Remote Sensing/GIS