HDTenEightyP/NetNews huggingface dataset:
From: schaerer@isi.ethz.ch (Thomas Schaerer)
Subject: LM12 Power-Opamp
Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH
X-Newsreader: TIN [version 1.1 PL6]
Date: Fri, 16 Oct 1992 17:44:14 GMT


In a earlier subject "LM12 need a circuit diagramm" 
I recomment to take the book  LINEAR DATABOOK 1
page 2-272 (issue 1988) and I have forgotten to
write the company.	Sorry!

The company is:		NATIONAL SEMICONDUCTOR CORPORATION

Greatings from Thoma
From: steuer@clam.rutgers.edu (robert Steuer)
Newsgroups: sci.electronics
Subject: Need Help with Op-Amps.
Date: 7 Oct 92 18:24:31 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

I just finished an Electric Circuits Lab and one of the circuits
involved an op-amp where the op-amp had its two bipolar power supply
connections, and a signal generator was feeding a sine wave into the
non-inverting input of the op-amp.  Then, a direct connection was made
from the output to the inverting input and the gain was measured.  It
was found that there was no change in the gain.  Then, the same
circuit was used but instead of the piece of wire going from the
output to the inverting input a 27k resistor was used and the gain
remained the same although one would have thought it would
decrease.(At least I did anyway!)  Is this because there was no second
resistor that would normally have gone from the inverting input to
ground?  That is all I can come up with because the formula to
calculate gain is Afb=(Rf)/(R1) + 1 for closed loop gain.
Can anyone verify that my assumption is correct or not?
                                  Thanks, Rob
From: drf40@cd.amdahl.com (Daryl Fortney)
Newsgroups: sci.electronics
Subject: Signal Generator CD
Date: 7 Oct 92 18:17:27 GMT
Reply-To: drf40@cd.amdahl.com
Organization: Amdahl Corporation, Sunnyvale, CA

I think that your idea for using a CD player as a signal generator is a
good one, but there are a few limitations to this which you may want to
consider.

	1> Sample rate is only 44Khz, therefore, the highest frequency you can
expect to see is about 20Khz.

	2> Compound signals, like square waves and triagular, often contain
much of there information in the harmonics of the base frequency, which
will be attenuated, aliasing a square wave into a sine wave for higher
frequencies.

	3> You may need an amplifier on output, since CD players don't have a
high current driving capability.

If your needs are for a relatively low frequency unit with low power
output, then good luck.  It definately is a cheap alternative.

	-df


-- 
Daryl Fortney						drf40@cd.amdahl.com
From: lordSnooty@cup.portal.com (Andrew - Palfreyman)
Newsgroups: sci.electronics
Subject: Re: what's a SAW?
Date: Fri, 16 Oct 92 19:34:59 PDT
Organization: The Portal System (TM)
Distribution: world
  <10400014@hpuplca.nsr.hp.com>

There's a device called an ACT which accomplishes 44 Billion MACs/second
which recently debut'd in the trade press. Comlinear Corp. makes it.
 --------------------------------------------------------------------------
| lord snooty @the giant |  Would You Like Space Potatoes With That?       |
| poisoned electric head |              andrew_-_palfreyman@cup.portal.com |
 --------------------------------------------------------------------------
Newsgroups: sci.electronics
From: jeffj@krfiny.uucp (J. Jonas)
Subject: Re: RFI/EMI shielding of a plastic box
Summary: spray on coating should perform well
Organization: Jeff's house of computer pieces
Date: Wed, 14 Oct 1992 19:17:13 GMT

In article <9210091338.AA09052@slc10.INS.CWRU.Edu> ah335@cleveland.Freenet.Edu
	(Richard Banks) writes:
>I have a plastic housing to put my circuit into but I'm worried about
>RFI interference.

There are spray coatings, both conductive and non-conductive just for that.
My electronics catalogues are all out of reach and I cannot recall
the names of the manufacturers
(I think Stephen-Miller specializes in cleaning solutions only).
Just look inside any plastic computer case (the Timex/Sincalir 1000,
the AT&T Starstation, Sun desktops among others)
and you'll find an aluminum coating inside the plastic.
It was sprayed on and can be done well after the manufacturing.
I even recall black fuzzy/matte finishes to attenuate high frequencies.

The real trick is in sealing the holes and edges from RF leakage.
Unless the lid has a good overlap/lip, you'll need RF sealing stuff
such as conductive gaskets or springs.
RF will leak through holes such as indicators and switches
and of course, any wires into the box.

- Jeffrey Jonas
jeffj@panix.com
-- 
-- 
Jeffrey Jonas

jeffj@panix.uucp
Newsgroups: sci.electronics
From: neal@cmptrc.lonestar.org (Neal Howard)
Subject: Re: Mystery Part!
Date: Tue, 6 Oct 1992 23:24:44 GMT
Organization: CompuTrac Inc., Richardson TX

It might be a high powered SBS (silicon bilateral switch) which is a specialized
kind of SCR/TRIAC-like doodad commonly used as the horizontal sweep output
device. These handle high frequency switching of the sawtooth-shaped waveform
of the horizontal output at high currents while imposing less ringing on the
signal than ordinary bipolar transistor based horizontal output amp circuits.

-- 
=============================================================================
Neal Howard (neal@cmptrc.lonestar.org)        CompuTrac, Inc. (Richardson,TX)
DoD #686   '91 XLH-1200      '70 Kawasaki G4-100cc    '69 Cougar XR7-GT390
	   Ensoniq VFX-SD    Kramer Pacer guitar      '70 429CJ(needs a home)
"how often you get much more drunk than you ought to on a Friday night...
...about once a week" -  Tom Yates
=============================================================================
From: dino@inqmind.bison.mb.ca (Tony stewart)
Newsgroups: sci.electronics
Subject: Re: Phone Circuit Help Needed
Date: Thu, 15 Oct 92 00:42:08 CDT
Organization: The Inquiring Mind BBS  1 204 488-1607

<DI3QC@CUNYVM.BITNET> writes:

>      I would like some help with a project I am working on. I am trying to bu
> d a circuit using a 68hc11e2 which will sense a phone ringing, pick up on n r
> gs and then wait for a n digit code. Once correctly entered the user will get
> new dial tone via the switching to another line. Are there any circuits all r
> dy available to do such? Any ideas to this project I could use some help.
> 
> 
> 
>                                                   Alex Jeannopoulos

Sounds like a small PBX job.  You're best off rectifying the Ring signal 
to a TTL level using a Schmitt inverter, resistors, diodes and cap, or 
chip with Ring DETECT cct. Motorola has a handful of telecom chips to do 
what you want. You need a SLIC chip to give the STD LINE INTERFACE CCT to 
a telephone line and a crosspoint matrix to connect phone lines. I think 
MITEL has invented these over a decade ago in Kanata Ontario. Check these 
companies for Application books for your solution. The SLIC will 
interface to a DTMF decoder which will interface to your micro and the 
RING DETECT can be used as an interupt signal to enable the DTMF codes to 
be scanned in and processed to control your CROSS-POINT SWITCH and then 
back to your SLIC chip for each phone circuit.

Tony .STewart

WinterPeg Canada

'av FuN

dino@inqmind.bison.mb.ca
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607
Xref: sparky sci.electronics:16693 rec.motorcycles:35111 rec.radio.cb:1137 rec.radio.swap:2681
From: pa_ross@csd.uwe.ac.uk (Mr Rossy)
Newsgroups: sci.electronics,rec.motorcycles,rec.radio.cb,rec.radio.swap
Subject: Re: The Communicator
Date: 7 Oct 92 12:59:50 GMT
Organization: University of the West of England, Bristol

A while ago I posted an article explaining that there was a company here that
sold a bug that had a range of 3km. Alot of people mailed me looking for the
address so here it is :-

	Suma Designs,
	The Old Workshops,
	95, Main Road,
	Baxterley,
	Warks,
	CV9 2LE
	England
	0827 714476 or Fax: 0827 712706

By the way they take credit cards and overseas orders and if you want the
3km range bug then the code is the "VT500 High Power room transmitter!"

Good luck,

				 Paul
				=----=
Newsgroups: sci.electronics
From: feg@cbnewsb.cb.att.com (forrest.e.gehrke)
Subject: Re: 25 ohm coax cable
Keywords: coax cable
Organization: AT&T
Date: Fri, 9 Oct 1992 20:10:11 GMT

In article <1992Oct8.120225.6247@fys.ruu.nl> vreeburg@fys.ruu.nl (Jurriaan Vreeburg) writes:
>
>>Put two pieces of 50 Ohm cable in parallel. It should be exactly the same.
>>Gary
>
>After reading Gary's answer I had some doubt of its correctness. It implies
>that by putting two 50 Ohm coax cables in series, one is able to create a 100 Ohm
>coax cable, which is certainly not true.
>
Gary didn't say anything about connecting the two pieces in series.

>I think that putting two cables in parallel doesn't change the impedance, since
>the impedance is defined as:
>
>                   L
>Z = square_root ( --- )
>                   C
>L: inductance per unit length
>C: capacitance per unit length
>
>What happens if we put two cables in parallel: both the inductance and the capacitance
>increase by a factor of two -> Z doesn't change!!! Putting two cables in series doesn't
>change the impedance as well, since L & C are defined per unit length, which don't
>change at all in that case.
>
You had better rethink the above statements.  Since when does paralleling
two inductances double the inductance?

Forrest Gehrke feg\@dodger.att.com

Newsgroups: sci.electronics
From: gmeiers@edsi.plexus.COM (Garrett Meiers)
Subject: Re: why is one prong on plug wider than the other?
Organization: Enterprise Data Systems Incorporated, Appleton WI
Distribution: usa
Date: Tue, 13 Oct 1992 00:36:53 GMT

mlevin@husc8.harvard.edu (Michael Levin) writes:


>    I am holding a plug, which is supposed to plug into a wall socket.
>One of the two metal prongs is wider, so that the plug only fits one
>way - not if you turn it over. Why is this? I thought the whole point
>of AC was that the poles change sinusoidally; so how can one be
>different from the other? Please direct replies to


In older metal appliances, before the 3rd grounding pin, one of the
120 lines were attached to the case of the appliance to be used as a
ground.  Back then there was no standard side of the 120 to be used as
ground so either one was used..  The reason the plug became polarized
and was wired with one prong being the ground, so you couldnt touch both
sides of 120 at the same time by touching a refridge and a toaster at
the same time...

Garrett Meiers

to touch a refridgerator and a toaster that
From: ks37+@andrew.cmu.edu (Kurt Jurgen Schaefer)
Newsgroups: sci.electronics
Subject: High Freq Anti Aliasing filters...
Date: 15 Oct 92 11:24:41 GMT
Article-I.D.: andrew.MerQJt_00VpZ04ZX5o
Organization: Fifth yr. senior, Math/Computer Science, Carnegie Mellon, Pittsburgh, PA

I'm interested in doing fast A/D conversion.  I have a flash converter
that claims to be able to sample at up to 15Mhz.  I was thinking of
something more like 10 or 3 for my fastest sampling rate. (I can't go above
about 10 because of the speed of my static rams, and I'm also leary of
strange problems due to stray inductance/capacitance at high frequences.)
I have basicaly two worries about the liner front end to the A/D.  One is
that since I'm going to be sampeling at differnt raits, I need to have a
number of anti-aliasing filters.  If I sample at 10Khz, 100khz, and 10Mhz
the I'm still going to have the fastest filter have a cutoff somwhere
below 5Mhz.  How do I go about building such a beast?  I guess I could make
an active filter out of high frequence op amps, but that sounds expencive.
(I'm basicaly designing a "digital scope" front end for my computer.)
I didn't see any examples of such a low pass filter in the lit, so I was
wondering how real systems do this.  Also I have to come up with input
conditioning spoo.  ie The ranging and overvoltage protection parts of
the scope. (And Keeping the input impedance high!) Blah! Any sugestions on
opamps to use, filter design, other sneekey tricks.   Would be greatly
apriciated.  The reason I wanted to sample at different raits is that I'd
like to be able to view a full wave of a 1Hz signal without haveing to have
Megs of fast ram on board to hold the sample.  Oh!  I also have to rig up
a trigger generating circuit of some type aswel.  Looks like I'm going to
learn a lot from this prodject. Is there some trick where I could have
the analog filter cut off some where and then use a digital filter to
clean it up more from there?  I'm basical looking for best bandwidth/price
that I can squeeze out of this design.  Sugestions on any fascet of the
design would be much apriciated!   Thanks,   -Kurt
Newsgroups: sci.electronics
From: schumach@convex.com (Richard A. Schumacher)
Subject: Re: RFI/EMI shielding of a plastic box
Organization: CONVEX Computer Corporation, Richardson, Tx., USA
Date: Tue, 13 Oct 1992 00:02:35 GMT
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

If you really need to kill EMI, it might be much simpler to
start with a metal box (aluminum extrusion, for example) than
to try to adequately shield a plastic one. Ever try soldering
aluminum foil? Copper foil or tinned wire mesh will probably
be easier to work with than aluminum foil, if you insist.
Newsgroups: sci.electronics
From: dionf@ERE.UMontreal.CA (Dion Francois)
Subject: Re: variable speed/pitch cd decks modification?
Organization: Universite de Montreal
Date: Wed, 14 Oct 1992 02:49:41 GMT

In article <1992Oct09.201431.26797@edsi.plexus.COM> gmeiers@edsi.plexus.COM (Garrett Meiers) writes:
>I am wondering if anyone has done this or know if it is possible without
>major modifications..
>
>I am looking for a way to modify a cd player to be able to vary the
>pitch approx +/- 10%.   I am hoping for there to be a potentiometer in
>the unit that is used for factory adjustment to specs..  The reason I

It's probably oscillator driven. Sorry.

>want to do this is that I am a dj and don't want to spend $2000+ to buy

You can buy denon or Sony with pitch control for less than 500$ a pair. The
Sony has a mic in, reverb, echo and voice remover to boot. I suppose this is
NOT for mobile DJ use? If it is forget that. Forget Technics. Get denon
CD-2000F for 1000$ dual cd. No joggle disk. The disk is on the 4000.

>a double cd-deck unit that the only difference is the variance in pitch
>control...I can build an external cueing and start/stop remote unit for
>the pair..
>
>I have not purchase a pair of decks yet, I was just wondering if anyone
>knows if there is such an adjustment...  Adjusting a pot would be best,
>but if I have to do it at a more advanced level, I would still be
>interested in any info on how I would be able to vari the pitch..

Put several crystals? Anyway, i would buy a denon if i were you.

>
>Thanks alot.  Please email and I will do a summary if there is any
>interest for such...
>
>Garrett
>------
>gmeiers@edsi.plexus.com	                          Garrett Meiers

Ciao,
--
Francois Dion
    '  _   _   _
 CISM (_) (_)  _) FM       Montreal , Canada       Email: CISM@ERE.UMontreal.CA
      (_)  / . _)             10000 Watts          Telephone no: (514) 343-7511
_______________________________________________________________________________
Newsgroups: sci.electronics
From: george@beta.ee.ufl.edu (George L)
Subject: Re: How do LCD TV screens work?
Date: Wed, 7 Oct 92 19:49:21 GMT

In article <7480121@hpfcso.FC.HP.COM> myers@hpfcso.FC.HP.COM (Bob Myers) writes:
>
>In an LCD screen, the pixels are not indivually "lit" - instead, there is
>a uniform backlight (which may just be reflected ambient light, or it may
>be constructed from, say, fluorescent tubes with a diffuser.  The individual
>cells (pixels) of the LCD panel act as shutters or valves for this light; when
>the cell is ON (a voltage exists across the cell), the cell cuts off the
>light (in the most typical mode of operation).
>
I have a recent SONY model, and it uses a miniature fluorescent light. I had 
a problem with my first one though. After the unit had been on and warmed up 
for a while, a couple of the pixels would remain continuously in the 
transmissive mode (this was an active matrix set). I have heard that the 
defect free yield rates on these displays is one of the factors that is 
keeping prices high. Any comments on this?

george@alpha.ee.ufl.edu
From: jeh@cmkrnl.com
Newsgroups: sci.electronics
Subject: Re: Filtering noise from a Van de Graaf
Date: 8 Oct 92 21:57:43 GMT
Organization: Kernel Mode Consulting, San Diego, CA

In article <1992Oct5.121847.20071@cc.uow.edu.au>, gkm@cc.uow.edu.au (Glen K Moore) writes:
> I have built a large Van de Graaf. Belt 6" wide and 6' high. Unfortunately
> it rresets computers and destroys chips in some equipment on the same mains.
> I have tried a few comercial flters with no success.
> 
> Does anyone have any ideas on suitable filters in these circumstances?
> 
> The Van de Graaf is to be used in a public science centre and thus there are 
> going to be many nearby devices.

Have you tried electrically isolating the drive motor from the generator... say
with a long rubber belt or non-conductive drive shaft? 

Also, give the VdG its own ground, using a ground rod installed just for the
purpose.  Do not ground it to the mains ground!  

	--- 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: daveg@peewee.nwc.navy.mil (David R. Gagnon           Code 3814                               Phone 939-1416)
Newsgroups: sci.electronics
Subject: Re: Smith Chart
Date: 8 Oct 92 16:46:57 GMT
Organization: NAVAIRWARCENWPNDIV, China Lake

In article <1992Oct8.060431.11383@ee.ubc.ca> cdacosta@ee.ubc.ca (DA COSTA ANTONIO L) writes:
>I recall that a while back someone on the net had a Smith chart
>set in postscript format.  If anyone has this file could they
>please email it to me? Thanks!
>

...and please send it to me also! Thanks in the extreme!
Dave
daveg@rftech.chinalake.navy.mil
Newsgroups: sci.electronics
Subject: Phone Circuit Help Needed
From: <DI3QC@CUNYVM.BITNET>
Date: Tuesday, 13 Oct 1992 19:50:17 EDT
Organization: City University of New York/ University Computer Center

     I would like some help with a project I am working on. I am trying to buil
d a circuit using a 68hc11e2 which will sense a phone ringing, pick up on n rin
gs and then wait for a n digit code. Once correctly entered the user will get a
new dial tone via the switching to another line. Are there any circuits all rea
dy available to do such? Any ideas to this project I could use some help.



                                                  Alex Jeannopoulos
From: eng20009@nusunix1.nus.sg (TAN GIM WEE)
Newsgroups: sci.electronics
Subject: 8085 Emulators for the PC
Date: 13 Oct 92 11:20:30 GMT
Organization: National University of Singapore
X-Newsreader: TIN [version 1.1 PL6]


Hello all you people out there! I would like to know if there are any
available 8085 emulators that allow 8085 codes to be executed on a PC.
Thanks a million!

--
---------------------------------------------------------
Tan Gim Wee
EE Dept, NUS
internet: eng20009@nusunix1.nus.sg
bitnet: eng20009@nusvm.bitnet
"Born to inspire, Destined to perform."
From: B521307@vmtecqro.qro.itesm.mx (Benjamin Millan Garcia)
Newsgroups: sci.electronics
Subject: Re: How do fluorescent lights work?
Date: 13 Oct 92 03:55:17 GMT
Organization: Instituto Tecnologico de Monterrey, Campus Queretaro

have some of these lights, and they got broken very quickly. (excuseme
In article <1992Oct4.160255.29702@doug.cae.wisc.edu>
siegel@hprisc-28.cae.wisc.edu (Jeffrey Siegel) writes:
 
>
>How do fluorescent lights work? I am specifically
>interested in the steps that occur when you turn on
>a fluorescent light. I took one apart and found a
I have many of these lights, but i got worried because
they became broken very quickly. Then i broked one, and i saw
that the starter was a capacitor that permits to give energy to
the light. This starter also has a pilot. (i dont know why).
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Newsgroups: sci.electronics
Subject: Re: Smith Chart
Date: 10 Oct 92 17:58:12 GMT
Distribution: usa
Organization: AI Programs, University of Georgia, Athens

Hmmm, how old is Smith's copyright and has it been renewed, I wonder?
When did the Smith Chart originally come out?

-- 
:- Michael A. Covington     internet mcovingt@uga.cc.uga.edu 
:- Artificial Intelligence Programs       phone 706 542-0359
:- The University of Georgia                fax 706 542-0349
:- Athens, Georgia 30602 U.S.A.          amateur radio N4TMI
From: jarinie@sulo.otol.fi (Jari Niemel{)
Newsgroups: sci.electronics
Subject: How to measure xyz-coordinates
Date: 16 Oct 92 09:12:04 GMT
Organization: Oulu Institute of Technology, Finland


I want to know how it is possible to measure what transmitters
position is in xyz-coordinates ?

So let's assume that i have 4 receivers positioned like:

	-one in origo
	-one in 2m via x-axel from origo
	-one in 2m via y-axel from origo
	-one in 2m via z-axel from origo

All can receive same frequency that the transmitter transmits.
I just want my comp. to read the position of the transmitter
(was it clear enough ???)

The resolution must be 200dpi or even better !

All ideas or solutions are more than wellcome. :)

-- 
Jari Niemela                       * I am  
Oulu Institute Of Technology       *  a happy
jarinie@otol.fi                    *   user of OS/2 2.0
Newsgroups: sci.electronics
From: levy@levy.fnal.gov
Subject: Re: Thunderstorms
Organization: Fermilab Computing Division
Date: Wed, 7 Oct 1992 19:59:16 GMT

>   We've seen lots of theory, but only a few experiences, of lightning
> doing damage to computer equipment.  Would anyone have some details
> about damage done to equipment?  This might give us a better idea of
> how much of a problem lightning actually is, direct hits, EMP, etc.

A few years ago, lightnihg struck the chimney of my house, and started a fire
in the attic.  In the immediate area where the lightning hit, there are no
phonw wires, but I later found out that one of ny AT&T electronic phones was
dead.  Also, my modem, the mux in my computer that it was connected to, and a
terminal were also hit.  There was no other damage to the computer other than
the serial mux.

--M

From: smithj@hpsad.sad.hp.com (Jim Smith)
Date: Tue, 6 Oct 1992 21:30:12 GMT
Subject: Re: Help with tube amp requested.
Organization: HP Signal Analysis Division - Rohnert Park, CA
Newsgroups: sci.electronics

In sci.electronics, rej@sal.wisc.edu (Randy Jones) writes:


    My Scott Stereomaster 200B is acting up. After about a minute past its
    initial warm-up, the left channel launches into a hellacious crackling.
    Occasionally the crackling stops, and the highs disappear from that channel
    altogether above, say, 500 Hz, so that Liz Fraser goes mmfwwmf mmfmrrmf.
    The right channel is just fine.  Needless to say, this bothers me.

    The crackling sounded somewhat like an intermittent connection, so I cleaned
    all the switches but this had no effect. And that's about where my valve amp
    expertise ends.

    So, if you know about valve amps in general or mine in particular, I'd be
    real happy if you'd contact me. Specs, schematics, or other lore would
    be most welcome. 

Your problem is clearly due to cold anodes.  When a tube gets old, its
heaters sometimes get frail, and this can cause its anodes to get cold.
So, of course, it then uses a getter to get an emissions blanker, which
it wraps around its anodes.  The electrons then can only travel to the
cathode through the blanker, causing them to "grid" or lose bandwidth
due to the blanker's muffling effect.

Unfortunately, since tube heaters are not user-replaceable, there's not
much that you can do.  If your Stereomaster has any screwy-turny-thingies,
you might want to diddle them and see if you can get your anodes to respond
by ungetting their emissions blankers, but if any Nyquist Eddies occur during
this procedure, I can't be held responsible for the outcome.

I really hope this helps a lot,
				- Jim

Newsgroups: sci.electronics