HDTenEightyP/NetNews huggingface dataset:
From: tjgerman@53iss6.Waterloo.NCR.COM (Trevor German)
Newsgroups: sci.electronics
Subject: Need Help with Op-Amps
Date: 8 Oct 92 15:18:51 GMT
Organization: Imaging Systems Division, NCR Corp, Waterloo, Ont., CANADA


Re: steuer questions

 [STUFF ABOUT OPAMP GAIN DELETED]

	Ok what you had was a classical negative feedback amplifier
like so. When connected in this manner you can think of the op-amp
						  as a device which
	Vi	      |\			  will adjust its 	
	--------------|+ \  			 to make the inputs
                      |    \            	 the same. That is	
	              |      >----------Vo 	 with an applied 
		      |	   /      |		 Vi of 1V the output
	         -----|-  /       |	 will be adjusted such that 
		|     |/          |	 the resistor division supplies
                |	R2	  |	 one volt to the neg pin.
		|------/\/\/\-----
		|			    Notice that the current 
		< R1			 through R2 virtually all goes
		>			through R1 since the input 
		|		impedence of the amplifier is large.
		|		If you do a bit of simple math here
		GND		You will find the gain = (R2+R1)/R1

				examples
				If R1=R2 the gain = (1+1)/1 = 2
				If R1 = 1K & R2 = 4K
					 The gain = (1+4)/1 = 5
	      
	Notice, when keeping R1 constant, increasing R2 increases the
	gain. Conversely decreasing R2 makes it less to a minimum of
	one when R2 = 0. In both your examples R1 was
	very large indeed being the input impedence of the device itself.
	In the first case R2 was nearly 0 (wire resistance) therefore
	you had (K + 0)/K where K was the imput impedence. ie K/K = 1
	In the second example you made R2 not zero but still very much
	smaller than the input impedence therefore the gain did not
	seem to change appreciably. If you had made R2 large enough you
	would have had an increase in gain as it started to come within
	orders of magnitude of the devices input impedence. By this time
	though the size of the impedences would have made the circuit
	very susseptible to noise.

--
       >|  "Only average people            | Trevor J German BSc    |<
       >|        never make mistakes."     | NCR, Waterloo, Ontario |<
       >| tjgerman@53iss6.Waterloo.NCR.COM | Canada.                |< 
Newsgroups: sci.electronics
From: jhp@sactoh0.sac.ca.us (Jim H. Puga)
Subject: Chaser lights
Summary: How do they work?
Keywords: lights
Organization: Sacramento Public Access Unix
Distribution: usa
Date: Fri, 9 Oct 92 19:33:11 GMT

Does anyone out there know where I can find a book or schematics
for chaser lights?  

I'd like to build some but not really sure how to go about it.  I
know of a couple of ways but I think I'll end up using miles of
wire to do it.  I would like to keep the wire down to a minimum.

Thanks in advance for the help.

-- 
-------------------------------------------------------------
- jhp@sactoh0.SAC.CA.US    What else can I say?             -
-------------------------------------------------------------
Newsgroups: sci.electronics
From: rick@cs.sunysb.edu (Richard Spanbauer)
Subject: Re: Smith Chart
Organization: State University of New York, Stony Brook
Distribution: usa
Date: Mon, 12 Oct 1992 14:10:53 GMT

In article <1992Oct10.175812.1324@athena.cs.uga.edu> mcovingt@aisun3.ai.uga.edu (Michael Covington) writes:
>Hmmm, how old is Smith's copyright and has it been renewed, I wonder?
>When did the Smith Chart originally come out?

	Did Smith hold the copyright?  According to a reference I have (1)
	in front of me, he published the smith chart in Jan 1939 Electronics
	(and Jan 1944 Electronics).  That being the case, wouldn't Electronics
	hold the copyright?

	For the copyright police among us, it was custom at University of 
	Buffalo to exercise ones photocopying rights when the need arose 
	for more smith charts in the T-line class.  I don't think anyone
	(prof or students) purchased the charts from a publisher.  Given
	the focus of the moment, ie passing the course, it never occurred to
	us that we may have been stomping on Mr. Smiths intellectual property
	rights ;-)

>:- Michael A. Covington 

					Rick Spanbauer
					SUNY/Stony Brook

(1) Johnson, Walter C., Transmission Lines and Networks, (c) 1950, McGraw-Hill,
    pg 128.
From: jimc@tau-ceti.isc-br.com (Jim Cathey)
Newsgroups: sci.electronics
Subject: Re: How do fluorescent lights work?
Keywords: flurorescent
Date: 12 Oct 92 20:46:46 GMT
Distribution: usa
Organization: ISC - Bunker Ramo, Spokane, WA

In article <1992Oct9.005131.535@u.washington.edu> whit@milton.u.washington.edu (John Whitmore) writes:
>	A starter is a small time-delay relay, with a bimetallic
>element in a neon tube.  On turning the fluorescent lamp ON,
>the relay is initially CLOSED, and power flows through it to
>heat the filaments on the ends of the tube.  After a short

Line
-----------------------------------------
                                        |
---BALLAST-----]                 [------|
               ]     TUBE        [
               ]                 [
           ----]                 [--------
           |                             |
           |                             |
           -----------STARTER-------------

This is backwards.  Initially the starter's contacts are OPEN, and the
starter glows because it's just a neon bulb with a bimetallic strip
hanging between the electrodes, and full line voltage is present across
the electrodes of the starter.  After a short time, the heat of the the
discharge causes the starter to be shorted out by the bimetallic strip,
which passes line current through both heater filaments of the
fluorescent lamp (and the ballast).  As the starter is shorted out, the
discharge within it stops and it starts to cool off.  Meanwhile, the
fluorescent tube is heating up.  When the starter's contacts open, the
heavy current flow stops.  This pisses off the ballast, which promptly
delivers a healthy inductive kick to its tormenters, which arcs over the
fluorescent tube and starts the lamp running.  (I'm not entirely sure
why the inductive spike prefers to leap across the tube instead of going
'round through the starter, but it may be that the inductance of the
coiled heater filaments in the tube is enough to discourage this.)  The
ballast then functions as a current limiting device.  Simple, cheap, and
effective.  At least until either the starter or the lamp wears out. 

Replace the starter with a momentary contact starting switch, and you've
got the old-style lamp, which is seen even in new equipment.  My Logan
lightbox has a hold-it-in-to-start switch, for example.

-- 
+----------------+
! II      CCCCCC !  Jim Cathey
! II  SSSSCC     !  ISC-Bunker Ramo
! II      CC     !  TAF-C8;  Spokane, WA  99220
! IISSSS  CC     !  UUCP: uunet!isc-br!jimc (jimc@isc-br.isc-br.com)
! II      CCCCCC !  (509) 927-5757
+----------------+
			"PC's --- the junk bonds of the computer industry"
Newsgroups: sci.electronics
From: finns@hal.nta.no (Finn Stafsnes FBA)
Subject: Re: halogen lamps and infra-red emission
Keywords: halogen infra-red
Organization: Norwegian Telecom Research
Date: Fri, 16 Oct 92 10:03:10 GMT

In article <1992Oct16.055626.2869@trl.oz.au>, ginger@hydrus.trl.OZ.AU (Jeremy Ginger) writes:
|> 
|> Hi everyone,
|> 
|> I was "told" that halogen lamps emit infra-red rays.
|> 

Well, all bulbs with a filament emit _some_ infrared radiation. 
The spectrum emitted from the filament (black body radiation) 
depends upon the temperature of the filament. Higher temperature 
will shift the spectrum towards the blue (or UV).
 
A normal halogen lamp is designed to run at a higher temperature 
than ordinary (non-halogen) filament lamps. Consequently the 
_filament_ will emit a smaller fraction of infra red light (IR)
compared with the filament in a normal lamp.

Another difference is the glass bulb. Ordinary lamps use "ordinary"
glass, stopping UV light, if present from the filament, and I believe 
it will also stop most IR light. Halogen lamps uses quarts bulbs. 
Quarts will transmit more of the UV, especially the range with 
wavelength just shorter than visible violet (UVA).

Therefore I believe that the biggest difference between halogen and 
normal lamps is that halogen lamps give you more light and especially
in the blue and UV part of the spectrum.


Finn
From: rwc@ius4.ius.cs.cmu.edu (Randy Casciola)
Newsgroups: sci.electronics
Subject: 16 bit wide EPROMS??
Date: 12 Oct 92 12:05:59 GMT
Article-I.D.: cs.Bw0CA0.LM9.2
Organization: CMU Vision and Autonomous Systems


Hi,

We are designing a modular control system for robotic arms in
which each joint will have its own microcontroller and other
associated hardware.  It uses a 16 bit Siemens processor.  It
also must be extremely tiny (on the order of 2.5" x 2.5").
Therefore, I would like to use 16 bit wide EPROM for program
storage in lieu of two 8 bit wide ones to conserve real estate.
They should hold at least 16kbytes(8k x 16), but more would not
hurt.  I would be great if they were 100ns or better, but 
anything would work since the code could be downloaded into fast
SRAM on powerup.  They should also be UV erasable, but EEPROM
would also work.  I know about the PSD3XX from WaferScale Integ.
(WSI).  This might be OK but it is more than we need (it includes
PLD and SRAM).  I checked the IC master but couldn't find much.
Does anyone know of anything like this?  I would like to hear from
you if you do.

Thanks in advance,

Randy Casciola
Research Engineer
The Robotics Institute
Carnegie Mellon
Pittsburgh, PA 15213
From: an938@cleveland.Freenet.Edu (George II Lenzer)
Newsgroups: sci.electronics
Subject: CD Player filtering
Date: 9 Oct 92 03:54:19 GMT
Organization: Case Western Reserve University, Cleveland, Ohio (USA)
NNTP-Posting-Host: slc4.ins.cwru.edu


	I would like to know if there is a way that I can find
the filtering section of a CD player by looking for certain 
components.  I would like to be able to tap the signal from my 
CD before it is filtered.  Is there a visible way to discern the
filter section?  Something along the lines of finding the AF in
a radio.
						George II Lenzer

-- 
"I'll let you in on a little secret.
	The whole universe is totally INSANE!!!!"
						Mr. Natural
From: pusateri@duke.cs.duke.edu (Thomas Pusateri)
Newsgroups: sci.electronics
Subject: zapping nicad batteries
Keywords: nicad batteries
Date: 16 Oct 92 20:32:47 GMT
Organization: Duke University Computer Science Dept.; Durham, N.C.

Hi,
	I was wondering if anyone knows of a circuit to zap an old nicad
battery. I have heard that nicad's that don't hold a charge any more can
be revitalized by charging up a capacitor and discharging it on the nicad.
I have a laptop computer that won't stay charged up anymore and they
want several hundred bucks for a new battery (AST premium exec).

Please repspond by email if possible.
Thanks for any info

Tom Pusateri
pusateri@cs.duke.edu
Newsgroups: sci.electronics
From: mmpjh@angelo.amd.com (Javed Hussain)
Subject: Cross references of Transistors
Organization: AMD
Distribution: usa
Date: Thu, 15 Oct 1992 20:52:03 GMT

Hello!	
I have a burglar alarm made in Tiwan. The control board has couple of  
transistors with the following markings:	
		C945
		8050	
I would like to know what type of bipolar transistors (NPN or PNP) and what
is their full part number is and any cross references to get an equivalent
transistor. Also, if you can tell me the source to buy from will greatly
help me.

Thanks in advance for any info.

Javed   mmpjh@amd.com
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Newsgroups: sci.electronics
Subject: Cold anodes; was: Re: Help with tube amp requested.
Date: 7 Oct 92 15:25:11 GMT
Article-I.D.: athena.1992Oct7.152511.26161
Organization: AI Programs, University of Georgia, Athens

In article <1840072@hpsad.sad.hp.com> smithj@hpsad.sad.hp.com (Jim Smith) writes:

>Your problem is clearly due to cold anodes.  When a tube gets old, its
[etc]

Datelined April 1, of course?

ROFL!

Or as we say in Morse code, ".... .. .... .. .... .."



-- 
:- 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: sane@bbiw02.enet.dec.com
Newsgroups: sci.electronics
Subject: Looking for : C Compiler for Intel 8751
Date: 13 Oct 92 04:13:17 GMT
Reply-To: sane@bbiw02.enet.dec.com ()
Organization: Digital Equipment Corporation


Hi Internet Fraternity,

	Subject says it all. If anyone knows of pl let me know.

	Enjoy!!

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                                               Phone  - (022) 642 0632
-----------------------------------------------------------------------------
From: pauls@trsvax.tandy.com
Date: 12 Oct 92 16:55 CDT
Newsgroups: sci.electronics
Subject: Re: CD+G/CD+MIDI specs?
Message-ID: <288200018@trsvax>
Nf-ID: #R:misty.boeing.com:68660003:trsvax:288200018:000:251
Nf-From: trsvax.tandy.com!pauls    Oct 12 16:55:00 1992


Snooty corporate answer to follow:

You are only allowed to own a copy of the specs if you have a paid-up
liscense from Sony/Philips. The CD/G and CD/MIDI are supplements to the
"red Book" (audio) spec.

That's why they aren't in Ken Pohlman's book.
From: paula@uupms.UUCP (Paula Stockholm)
Newsgroups: sci.electronics
Subject: Need Help with Two Phone Projects
Date: Thu, 15 Oct 92 10:59:16 GMT
Reply-To: paula@nlbbs
Distribution: world
Organization: The Electronics Workbench


In article <1687FECF3.STATRAA@YaleVM.YCC.Yale.Edu> STATRAA@YaleVM.YCC.Yale.Edu writes:

 > 
 > I need to build a Hold circuit for a phone line.  It would simply allow
 > me to put the line on 'hold' and once having done so, I would be able to
 > hang up the phone, or even unplug it, and still not lose my connection,
 > so that I could come back to it.
 >  
 > Also, if anyone knows how to do this easily, I would like to build a
 > multi-line adaptor for my single line phone.  It would basically do what
 > those fancy office phones, with the row of illuminated buttons do -

 >Travis, the multi-line phone features you describe were and are often
 a feature of the KSU - that box in a storage closet. There are little
 transistor, diode, resistor hold circuits in some of the hobby books
 but I am not aware of any that will let you unplug the phone.

        What I did for this two-family plus one business farmhouse is
        wrangle a deal with a local interconnect company for a 1A2 phone
        system. These are the aging multi-button phones I think you
        might have in mind. "Interconnects" are the non-telco companies
        that offer office communications systems.

Then, of course, if money is no object <g> there are gobs of phone
systems that will do these things and more. SW Bell makes one that
handles four incoming lines plus has a carrier-current (wireless)
dial intercom built in. But, again, I doubt you'ld find one that allowed
you to unplug the holding phone without going to a Key Service Unit
(money tree).
From: phillip@bartal.com (Phillip M. Vogel)
Newsgroups: sci.electronics
Subject: Auto Fax switch ?
Date: 11 Oct 92 13:29:16 GMT
Organization: Bartal Design Group, Inc.



Does anyone know the frequency of the tone used to switch automatic
Fax switches from 'voice' to 'fax'? I'm talking about the ~1KHz beep
that the sending fax makes about every two seconds before it receives
the answer tone from the receiveing fax.

Reply by mail, or post here if you want.

Thanks for your help,

Phillip
--
Phillip M. Vogel, President             | "I like pussy, but I don't like Bush"
Bartal Design Group, Inc.               | Domain: phillip@bartal.com
318 Marlboro Road, Englewood, NJ 07631  | (201)567-1343   FAX:(201)568-2891
Newsgroups: sci.electronics
From: liberato@dri.com (Jimmy Liberato)
Subject: Re: Help! My CD player sk-sk-sk-sk-skips
Reply-To: liberato@dri.com (Jimmy Liberato)
Organization: Novell/Desktop Systems Group, Monterey Development Center
Date: Wed, 7 Oct 92 03:09:54 GMT

dahls@fhydra.dnet.unit.no (Joern Yngve Dahl-Stamnes) writes:

>Thus spoke the keyboard of kevinlu@yoyo.cc.monash.edu.au (Kevin Lu):
>>
>>I've develop a scratch on one of my CDs and now the CD player doesn't play
>>one track correctly (i.e it skips, but only on that track on that cd)...
>
>I also got a CD with a scratch that make my CD sk-sk....ski...skip.
>Someone have told me that there might be some cure for the CD...

Go to to a auto paint supply store and get the finest wet/dry sandpaper
they have (the kind for rubbing out lacquer, something like 1200).
Carefully sand radially (across tracks). Finish with Glass Wax.  Of course
it is probably not worth $15 of your time to do all of that!

--
Jimmy Liberato   liberato@dri.com
                 ...uunet!drivax!liberato
From: fisk@netcom.com (Benjamin Fisk)
Newsgroups: sci.electronics
Subject: Re: SVGA monitor repair
Summary: How long?
Keywords: VGA repair
Date: 16 Oct 92 20:32:11 GMT
Distribution: usa
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

In article <1992Oct16.145528.13119@alw.nih.gov>, arm@helix.nih.gov (Andrew Mitz) writes:
> I damaged my SVGA monitor (AAmazing) by connecting it to
> a SVGA card with a higher scan rate.  (The card was 72 Hz
> at 600X800 and the monitor could not handle it.)  Now
> white looks almost yellow.

How long did you leave it on the higher rate before the damage became
apparent?  At the local computer shops they usally drive the lower freq.
monitors at higher rates w/ out much apparent damage.


-- 
Ben Fisk : fisk@netcom.COM
Newsgroups: sci.electronics
Subject: SpeakerBuilder magazine info.
From: pandey+@cs.cmu.edu (Manish Pandey)
Date: Sat, 10 Oct 1992 20:01:58 GMT
Organization: School of Computer Science, Carnegie Mellon


 Here is some info I received from Ken (kdrolt@athena.mit.edu).
I am forwarding it to this newsgroup on his behalf. 

	SpeakerBuilder
	P.O. Box 494
	Peterborough, NH 03458-0494

	(603) 924-9464        fax: (603) 924-9467

	subscriptions (as on 1/92): $25 for one year (6 issues)
				    $45 for two years (12 issues)

If you have any interest at all in 'building your own' this is the
magazine for you.  There's also a classified section at the back of
each issue that has 'For Sale' stuff, as well as local acoustics and
speaker chapters across the USA, and abroad.

The magazine also welcomes contributions from readers (i.e. you write an
article about your speakers, send it in, and if they print it. you get a
nominal $$$ payment (I don't know how much, I've never done it).

cheers,

Manish
-- 

Manish Pandey
SCS-CMU 412-268-3054(w) 412-421-8403(h)
pandey@cs.cmu.edu
Newsgroups: sci.electronics
From: kludge@grissom.larc.nasa.gov (Scott Dorsey)
Subject: Re: variable speed/pitch cd decks modification?
Organization: NASA Langley Research Center and Reptile Farm
Date: Tue, 13 Oct 1992 19:05:35 GMT

In article <Bw2oCt.7vE@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>In article <1992Oct09.201431.26797@edsi.plexus.COM> gmeiers@edsi.plexus.COM (Garrett Meiers) writes:
>>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...
>
>I'm not up on the details, I could be wrong... but my understanding is
>that you're still thinking of the previous generation of electronics.
>The timing in a CD player is probably set by a crystal oscillator,
>supplying timing signals for the digital electronics that control all
>the actual workings of the player.  This isn't anything as simple as a
>motor-speed adjustment; indeed, CD-player motors don't run at a constant
>speed, they're speed-controlled by the digital stuff.

They are all set by a crystal oscillator.  I know that the first and second
generation Phillips chipsets would work with a +/- 20% variation in the
oscillator frequency (although obviously the anti-aliasing filter let some
strange stuff through if you slowed the sound down).  You can just inject
a signal from a homebrew LC oscillator into the crystal socket, and it works
quite nicely.  Not as easy as twisting a pot, but not that much harder.
--scott
Newsgroups: sci.electronics
From: ssave@ole.cdac.com (The Devil Reincarnate)
Subject: Re: Positive and negative side of diode
Organization: CDAC, WA
Date: Fri, 9 Oct 1992 20:37:34 GMT

In article <1b2pfuINN2rn@usenet.INS.CWRU.Edu> ah335@cleveland.Freenet.Edu (Richard Banks) writes:
>Please excuse my ignorance but I'm new at this.
>I'm putting together an electronic circuit and would like to know
>which side is positive and which is negative.  I guessed that the side
>which the ring on it is negative.  Is that right?  Please respond as
>quickly as possible and when I get a reply I'll cancel this article
>thanks.

  This is not ignorance.  The last time I got into trouble when the
ring was not the negative. I was building a power supply bridge.  
There is no standard!   Use a multimeter, use a battery with an led.  
Or look it up in the data-book.

-S
ssave@ole.cdac.com
Newsgroups: sci.electronics
From: jon_sree@world.std.com (Jon Sreekanth)
Subject: Re: Lineman's Set
Organization: The World
Date: Sat, 10 Oct 1992 15:24:39 GMT

In article <92283.200253DI3QC@CUNYVM.BITNET> <DI3QC@CUNYVM.BITNET> writes:

	Does anyone out there know where I can purchase a telephone lineman's set.
   I will also buy it used if anyone has one to sell. Any companies that carry
   any type of telephony equipment I would be interested in. Thanks.


Specialized Products Company, 800-866-5353

/ Jon Sreekanth

Assabet Valley Microsystems, Inc.           |  Fax and PC products
5 Walden St #3, Cambridge, MA 02140         |  (617) 876-8019
jon_sree@world.std.com                      |