HDTenEightyP/NetNews huggingface dataset:
From: smithm@liciren.li.co.uk (Martin Smith)
Newsgroups: sci.electronics
Subject: Dual opamps
Summary: Analogue design - the reality between 1 and 0
Keywords: Operational amplifiers
Date: 5 Nov 92 17:24:52 GMT
Followup-To: Richard Bank's query
Organization: Lucas Powertrain Systems, Electronic Control Group, UK

> ah335@cleveland.Freenet.Edu (Richard Banks) writes:

> I'm building a circuit where I need high gain.  I was going to
> get two single opamps and send the output of one to the input
> of the other one.  But would it be possible for me to just get
> a dual opamp IC and send the output of one to the input of the
> other on the same chip?!  If this is possible is it a standard
> practice?

Yes this is perfectly possible, dual opamps were developed
specifically for reducing the component count and for saving
space on analogue designs.  You can treat them just like two
separate devices only they're in the same package (it saves on
decoupling capacitors too).  A couple of points to watch out for
though...You mention high gain, but don't specify whether it's at
DC, DC + AC, audio, high speed etc.  Because of the way opamps
are manufactured with on-silicon trims to reduce errors inherent
in the transistors, a single device can have more tweaks than a
dual crammed into (roughly) the same area of wafer.  This means
that, in general, a single opamp will have better spec's than the
same architecture fabricated as a dual.  Equally, a quad will be
slightly worse than a dual.  Thus if you want good DC precision
with high gain then two single OP07 devices will probably be your
best bet, especially if you're pushed for space and intend using
an 8 pin DIL, where you won't have the offset trim facility
available.

If you've got any further queries, e-mail me at the address below
(both work or so I'm told by our computer guy), this is the best
method of getting hold of me as sci.electronics tends to be quite
large and I can't guarantee to be able to read all the entries.
-- 
=================================================================
Martin Smith                             My opinions are unlikely
Mail:  smithm@eg.lucasauto.co.uk         to reflect those of this
     or smithm@liciren.li.co.uk          glorious institution....
From: crichmon@sedona.intel.com (Chris Richmond)
Newsgroups: sci.electronics
Subject: My TV is sort of broken
Date: 11 Nov 92 15:00:17 GMT
Reply-To: crichmon@sedona.intel.com
Organization: Intel Corporation
Originator: crichmon@sedona


Hi Folks,

	We have a Toshiba 19" color TV that had an accident.  It was
pushed off it's stand forwards and landed on it's face.  It fell about
18".  The problem it had for a while was that of funny colors.  Sort of
like what people used to do with Apple II and Atari computers to get
more colors than they supported (aliasing??).  The other problem is
that the picture brightness went away.  This happened about 6 months
ago, and the colors seemed to be OK now, but the brightness problem
persists.  Is this the sort of thing I can fix myself and where do I
start?  Unless special equipment is required I have the ability to do
this kind of work.

Thanks ahead of time, Chris
-- 
 Chris Richmond         |     Internet: crichmon@sedona.intel.com
 Intel, Corp. C3-21     |     Phone: (602)-554-8827
 5000 W. Chandler Blvd. |     This crazy is a world place. 
 Chandler, AZ  85226    |     My think losing I'm mind.
From: jasko@park.bu.edu (John V. Jaskolski)
Newsgroups: sci.electronics
Subject: Question Regarding Telephone PARTY LINES
Date: 5 Nov 92 15:15:07 GMT
Article-I.D.: park.JASKO.92Nov5101507
Reply-To: John_Jaskolski@cns.bu.edu
Distribution: sci.electronics
Organization: Boston University Dept. of Cognitive and Neural Systems


I am interested in building telephone bridges for party lines.
This would be a device that allows multiple callers to call in
and be "bridged" together so as to be able to all talk together
at the same time.  Ideally, the system would have several numbers
with any number of lines able to be dynamically allocated to
a given party line number.  For example, 5 people might call in
on line 1 (and be talking together), 7 people might be talking on
line 2, etc..  At another time 50 people might be on line 1 with
the teleconferencing system dynamically allocating the lines to each
number as needed.  What I am looking for is ANY INFORMATION
WHATSOEVER: chips that might be used, schematics, textbooks, vendors,
whatever.  These systems are also called Group Bridging Service (GBS)
systems and if purchased comercially they are expensive.

Thank You Very Much,
John V. Jaskolski

--
John V. Jaskolski, IMC                            Internet: jasko@cns.bu.edu
International Marketing Corp.                Bitnet: jasko%kenmore AT BUACCA
IMC of America                     UUCP: {harvard,uunet}!bu.edu!bucasb!jasko
From: t923335@minyos.xx.rmit.oz.au (IronEagle)
Newsgroups: sci.electronics
Subject: Vax 11/750 - Info needed
Date: 10 Nov 1992 02:24:58 GMT
Organization: RMIT Computer Centre
NNTP-Posting-Host: minyos.xx.rmit.oz.au
Summary: What is this machine, and is it worth the money?


I have been offered to purchase the above machine (and this probably
isnt the best place to post considering my questions) and I want to
know if it is worth the money or not.

What I DO know about it.

comes with:   500Mb fixed disk storage
	      120Mb removable storage of some sort
	      (media for above removable storage)


The price that I have been offered to purchase said machine for is 
  AU$2000

  I am interested to know some of the specs on this machine
  (processor, etc) and whether it sounds worth the money

  Thanks

  Damien

-- 
 ############################################################
 ##  Never assume the obvious, as it is rarely the truth!  ##
 ##t923335@minyos.xx.rmit.oz.au Iron@Eagle.aero.rmit.edu.au##
 ############################################################
Newsgroups: sci.electronics
From: jon_sree@world.std.com (Jon Sreekanth)
Subject: Re: PIC programmer.
Organization: The World
Date: Mon, 9 Nov 1992 14:35:01 GMT

In article <1992Nov7.140756.449@ludd.luth.se> d89-ahg@ludd.luth.se (Anders Hedberg) writes:


   Microchip lists a company called PARALLAX INC. selling such a thing for
   $199, how do I contact them ???

   I'm, also interested in other tools for the PIC16C5x series, please mail me!


Parallax is at 916-721-8217, fax 916-726-1905. I have their $199 
programmer; it also includes a pretty reasonable assembler. It's a
pretty neat little chip. 

/ 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                      |
Newsgroups: sci.electronics
From: bb11807@medtronic.COM (Brian A. Blow)
Subject: Re: need a pulse stretcher
Organization: Medtronic, Inc.
X-Newsreader: TIN [version 1.1 PL6]
Date: Thu, 12 Nov 1992 21:53:27 GMT

X1FT@VM1.CC.UAKRON.EDU wrote:
: Greetings,
:  
: I am in need of a simple circuit to stretch a pulse produced by a micro-tremor
: vibration detector.  I would like the circuit to run on 12v, which precludes
: (without adding a 5 v regulator) the use of a 74123 retriggerable monostable
: multivibrator.  Is there another device, relatively commonly available, that
: that runs on 12v that acts like a 74123 (CMOS maybe?).  Thanks!
:                                                            - Frank

Why not use a 555 timer?  They run on supply voltages of up to 18V.  It's not
CMOS, so it will consume around 10mA at 15V (according to National databook).


--Brian                   brian.blow@medtronic.com
                          (612) 574-4030
Newsgroups: sci.electronics
From: schuch@phx.mcd.mot.com (John Schuch)
Subject: Re: People tracker
Organization: Motorola Computer Group, Tempe, Az.
Date: Mon, 9 Nov 1992 17:50:58 GMT

In article <1992Nov6.164950.28812@njitgw.njit.edu> rxy5310@hertz.njit.edu (rolan yang ee stnt) writes:
>I threw together a motorized water gun that can rotate on the
>3 axis controlled by computer and stepper motors. I'm looking

What's the third axis? I presume two of them are altitude and azmuth.

>for an inexpensive way to 'track' people who would walk near it (within 15ft)
>possibly using ultrasonics, some photocells, or anything cheap (no radar,
>laser phase-shift or anything expensive).

Ultrasonics are probably the best bet. Rotate the beam, like they do on
the top of the HERO robot, and point at the closest thing. Actually, with
this you could also have it shoot when something enters a predetermined
range. Sounds fun :-)

John

Newsgroups: sci.electronics
From: pvr@wang.com ()
Subject: Re: TEC-200 film
Organization: Wang Labs, Lowell MA, USA
Date: Wed, 11 Nov 1992 13:33:04 GMT

ajackson@ernie.Princeton.EDU (Andrew William Jackson) writes:

>TEC-200 film

>Has anyone tried this stuff?  Supposedly you photocopy your
>PCB pattern onto it with a normal photocopier and then iron
>it onto a blank copper board, peel off the plastic substrate
>leaving the pattern behind - then you etch it.  Sounds like
>a great way to make boards without the hassle of using photo
>resist.

	Yes I have.   It worked as advertised.   The problem
is in ironing it to the circuit board.   The trace pattern 
has a tendency to mush as it is pressed onto the board.   This
was not too much of a problem on boards that had wide traces
that were widely spaced.   On boards with fine traces, 12 mil
traces on 25 mil centers, it was very hard to control.

	I had no problem with the film not releasing the
toner as some people have reported.   I did sand the board
with #320 sand paper.   I used a tight circular sanding pattern
to not have any directional adhesion bias.

	Interestingly, the copies produced in my Laser Jet III
were not all that dense.   I thought that is would be too porous
to be an effective resist.   The mushing effect caused the
toner particles to mush together producing a solid trace as well
as a wider trace.

	If the film could be pressed onto the board with
a very tightly controlled pressure at the correct temperature
then this process would probably work well.   An iron is
just too crude an instrument.


--
>>>>>>>>>>>> Peter Reilley ..... pvr@wiis.wang.com ..... KA1LAT <<<<<<<<<<<<<
                     Well, that about says it.
Newsgroups: sci.electronics
From: jmc@engr.uark.edu (John Carmack)
Subject: Need help with Zenith 12HO90 resto
Organization: University of Arkansas
Date: Mon, 9 Nov 1992 04:38:39 GMT

I just purchased an antique Zenith 12HO90, chassis #11C21, for the purpose
of restoration to original condition.  The problem is, on further inspection
of the chassis, it seems that the thing was rewired with a transistor amp 
(removed before I got to it) straight into the phono.  The loop antenna 
is missing, and there's an empty socket on the main chassis (the phono 
I think, but why so many pins?)   All the tubes are present and accounted
for, so it's not a tube socket.  

What I really need are the schematics, and better yet, a service manual 
for this puppy.  Seeing as it was the top-of-the-line console in the 
late 40's (my date estimate), one would think there would be service manual
other than the old Sam's or Ryder's for it.   Any help with this would be 
greatly appreciated.  

Please email me your responses, as I don't get to the nn often.

Thanks in advance
John Carmack
jmc@engr.uark.edu
From: U40348@uicvm.uic.edu (Jay Lorenzana)
Newsgroups: sci.electronics
Subject: JFET, HEXFET, SCR... Which one?
Date: 5 Nov 92 04:49:18 GMT
Article-I.D.: uicvm.92309.224918U40348
Organization: University of Illinois at Chicago


Dear Net:

I am trying to decide on a switching device to control
the power delivered to a line, and I need help.

The circuit is as follows:

-------
      |        -----------------------------
 HCMOS|        |    |                      |
      |    |-------S2                      |
      |    |   |    |                      |
     A|--------S1   |                      |
      |        |    |                    R Load
      |        |    |                      |
-------       +15  -15                     |
               |    |                      |
               -----------------------------
               |
                grnd
Given:
Line A controls Switch 1 and Switch 2, S1 and S2 respectively.
When S1 is open S2 must be closed and vice versa.
Switching speed = 9600 baud =~ 10khz.
Current thru Load = +-5Amps, +-20A spike.
Circuit is isolated from chip via opto-isolator.


Question:
What solid state device would work best and cost least
for S1 and S2?

I have thought about using NPN/PNP, JFETS, P/N-CHANNEL HEXFET,
and SRC's, type setups.  But what's the BIG difference?  I prefer
using the SRC's because they are least expensive, but I have
read that SRC stay on even when the gate is relieved if
there is large currents...... Please help.

Thanks in advance,
                  Jay



         Univeristy of Illinois
               at Chicago

                                   Internet: U40348@uicvm.uic.edu
                                   Bitnet  : U40348@uicvm.bitnet
From: acm@Sun.COM (Andrew MacRae)
Newsgroups: sci.electronics
Subject: Re: Cable TV Tech Question
Date: 9 Nov 1992 20:22:46 GMT
Organization: Sun Microsystems, Mountain View CA
Distribution: world
Reply-To: acm@Sun.COM (Andrew MacRae)
NNTP-Posting-Host: grendal.corp.sun.com

In article <1992Nov5.181038.17264@doug.cae.wisc.edu>, kolstad@cae.wisc.edu (Joel Kolstad) writes:
> If you REALLY want to keep on going with this STRAINED analogy, though,
> fine: As someone else suggested earlier, you can just go buy a distribution
> amp so that the cable company always "sees" a 75 ohm impedence going into
> your house, and the "power" you draw from their line is the same.


Sorry to inject a technical question into the ongoing controversy, but I
tried to do the above and got a strange result.

I split the cable after the in-line filter that unscrambles the Disney
channel and ran a length ~25 ft upstairs.  There I feed it into a distribution
amplifier and from that to two TVs (one about 20 ft, the other about 30 ft).

Everything is fine *except* that I don't get any thing on channels above 13.  I
checked the amp and it is supposed to amplify VHF, UHF, and FM.  The splitters
are supposed to split those as well.  I tried adding yet another amplifier
(again, one that amplifies VHF, UHF, and FM) downstairs right after the split,
but it didn't make a difference.

Anyone have a suggestion or two?

							Andrew MacRae
							
Newsgroups: sci.electronics
From: grier@bnr.ca (Brian Grier)
Newsgroups: sci.electronics
Subject: Re: Cable TV Tech Question
Date: 9 Nov 92 21:59:56 GMT
Organization: Bell Northern Research

> Everything is fine *except* that I don't get any thing on channels above 13.  I
> checked the amp and it is supposed to amplify VHF, UHF, and FM.  The splitters
> are supposed to split those as well.  I tried adding yet another amplifier
> (again, one that amplifies VHF, UHF, and FM) downstairs right after the split,
> but it didn't make a difference.

Question 1) Is the TV a cable-ready TV?
              If it is not you will note receive anything above channel 13.

If the answer to #1 is yes then...
         2) Have you switched to the proper cable mode, IRC in my case, 
            to allow your TV display channels above 13.

If your answer is yes to both I can not help. But you should not need
the extra amplifier.

Brian, WS1S
Bell Northern Research
Research Triangle Park, NC
bjgrier@bnr.ca
Newsgroups: sci.electronics
From: philip@mentorg.com (Philip Peake)
Subject: Re: 12 V -> 3V, 0.6 A
Date: Mon, 09 Nov 1992 18:32:28 GMT
Organization: Mentor Graphics
Keywords: 
Followup-To: 

In article <sehari.721325974@class1.iastate.edu>, sehari@iastate.edu (Babak Sehari) writes:
|> In <1992Nov9.114833.26094@bernina.ethz.ch> schaerer@isi.ethz.ch (Thomas Schaerer) writes:
|> 
|> I guess you could use gold wire to wire up your car, too! -:) Even though,
|> it has less resistance than regular wire;  the costs does not justify the
|> savings in this case.

Resistivity of gold is *higher* than that of copper.
The only reason that gold is ever used is that it doesn't oxidise.
It is usually only applied as a thin coating (plated).

If you want lowest power loss, use silver (or cool the whole thing
down a bit, and use superconducting ceramics :-).

Philip
Newsgroups: sci.electronics
From: sakaria@vipunen.hut.fi (Sakari Aaltonen)
Subject: Re: 68000 and Cache?
Keywords: 68000
Reply-To: sakaria@vipunen.hut.fi (Sakari Aaltonen)
Organization: Helsinki University of Technology
Date: Thu, 12 Nov 1992 22:21:22 GMT

In article <1dnt1fINNk0f@uranium.sto.pdb.sni.de> Josef Moellers <mollers.pad@sni.de> writes:
>........................
>You don't need any provisions for a cache, i.e. none in particular.
>All You need is a means to temporarily suspend operation of the CPU
>while You process a cache miss.
>........................

Yeah, well, I do know in a general way how caches operate. What I
don't know is how they are implemented with a 68000. What kind of
hardware will do the job, that sort of thing. Are any IC's available
for the purpose, for example? What do the accelerators use? I've
never seen one...
-- 
-----------------------------------------------------------------------------
Sakari Aaltonen                             Helsinki University of Technology
Email: sakaria@vipunen.hut.fi               ---- Finns Do It in the Snow ----
From: v064mcqs@ubvmsb.cc.buffalo.edu (Adam M Gandler)
Newsgroups: sci.electronics
Subject: Detecting a tone on a phone line
Date: 5 Nov 92 22:47:00 GMT
Organization: University at Buffalo
News-Software: VAX/VMS VNEWS 1.41


  I am desining a project that mutes my stereo when the phone rings
or the receiver is picked up. I want to find a way to remotely
activate or deactivate this device for when I use my modem. I want to 
have it so that if I pick up the phone and dial the *, its either
activates of deactivates. What is the simplest way to detect a touch
tone signal directly from a phone line. Is it simple as just
a 567 tone decoder?

	Thanks for any help,
			Neil Gandler
Newsgroups: sci.electronics
From: cstrockb@cs.sunysb.edu (Caleb Strockbine)
Subject: Re: Home Automation
Organization: SUNY at Stony Brook Computer Science Dept.
Date: Sun, 8 Nov 1992 23:51:07 GMT

In article <Damian_Wallace.03vu@panam.wimsey.bc.ca> Damian_Wallace@panam.wimsey.bc.ca (Damian Wallace) writes:

   Does any one know of Mail Order Houses that offer home automation
   equipment.  If so, please let me know.  

Funny, I saw a segment on CNN(?) just today about a guy who started automating
his home as a hobby and then turned it into a business. His company is called
Home Automation Labs, and they've got a catalog (there were copies lying on
the guy's desk in the clip).

Sorry, no address or number was given, so you'll have to track them down
for yourself. If you find an address, I'd be glad if you'd send it my way.

Caleb.
--
This message has been brought to you by the letters C and S and the number 3.
Newsgroups: sci.electronics
From: doherty@melpar (Kevin Doherty)
Subject: Re: Help: What is an Independent Current Source!?
Organization: E-Systems, Melpar Division
Date: Mon, 9 Nov 1992 13:23:18 GMT

steuer@clam.rutgers.edu (robert Steuer) writes:

>I understand an Independent Voltage source is like a battery and I
>understand that an Independent Current source can supply a current,
>but what is a REAL-LIFE example of an Independent Current Source?
>I have asked fellow students, my teachers, even a teacher with a
>Doctorate Degree and still I get hmmm, thats a good question!

If you're asking about a constant current source, there are quite a
number of ways of doing it.

For relatively low currents, an op amp will do the trick:

                    +-----------------------O
          I1 -->    | |\               <--\
                    | |  \                | I2
    Vref O---\/\/\--+-+ -  \            --/
               R      |     >---------------O
                +-----+ +  /
                |     |  /
                |     |/
               ---
                -
  To keep the negative input at a virtual ground, the amp outputs a
current equal and opposite to the input current (ie, I2=I1).  By using a
well regulated reference voltage one can set the output current with R
(Iout = Vref/R).

  A higher current alternative (up to 1.5 amps) can be kludged out of a
common 78XX series voltage regulator.  These devices are feedback based
linear voltage regulators; the regulator tries to keep its output pin
exactly XX volts above its reference pin.  The following circuit:

                   +---------+
                   |         |    R
     Vin O---------+IN    OUT+--/\/\/--+-------O Iout
                   |   REF   |         |
                   +----+----+         |
                        |              |
                        +--------------+       
will take an unregulated voltage Vin and provide a regulated Iout; it does
this by generating whatever output voltage is necessary to maintain its
rated voltage across the resistor R.  The output current is thus the rated
voltage divided by the feedback resistor.  Some restrictions: the voltage
compliance (ie, max voltage it'll generate to try to force the desired
current) is only Vin minus the rated voltage minus about 3 volts; also, the
78XX family is only good for maybe 32 volts Vin.  Also-use a power resistor.

							KMD
Newsgroups: sci.electronics
From: schaerer@isi.ethz.ch (Thomas Schaerer)
Subject: Re: Linear regulator circuits?
Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH
X-Newsreader: TIN [version 1.1 PL6]
Date: Fri, 13 Nov 1992 13:08:21 GMT

Adam Duff (duff@cs.wisc.edu) wrote:
: Does anyone have any pointers toward good example circuits for
: linear regulation?
: 
: I require a circuit with very low output impedance (say, a couple of
: microOhms) from DC to at least 100kHz.  Actual voltage stability is
: secondary.  Typical output voltages will be from 50 to 100 VDC.
: Currents from 2 to 6 Amps.

I can not give you an application-note but any rule of tumps to realize
a regulator with very low output-resistance:

	1. DC
	-----
	The most important thing is remote-sensing from +DC and GND from
	powered device back to the regulator. The openloopgain of regula-
	tor-amplifier must be very high. This is by using of modern opams 
	no problem.

	2. AC (Low-Frequency)
	---------------------
	For high speed regulation it's important to use an opamp with
	a high gbw  and also a high slewrate to result of a low output-
	impedance.

	2. AC (High-Frequency)
	----------------------
	For a low impedance with highfrequency you must close a capacitor
	very near parallel to the powered device. The capacitor must have
	a very very low inductance. 
	

I know that's easy said. To build this circuit is not easy. I constructed
much power-supply-devices, but no one with such less impedance. I wish you
good luck and let e-mail me if you have a solution. I am interested.

Greeting from Thomas
From: rxy5310@hertz.njit.edu (rolan yang ee stnt)
Newsgroups: sci.electronics
Subject: TV-VGA monitor
Summary: Converter???
Date: 9 Nov 92 20:05:31 GMT
Organization: New Jersey Institute of Technology, Newark, N.J.

I have a few spare televisions lying around and was wondering if it was
possible to wire the inner parts of a television to the input of a 
VGA monitor so that I could watch television through the monitor.
I don't have much experience with televisions or VGA monitors, but my
basic hypothesis would be to find the red, blue, green, and sync signals
in the TV and "plug" into the vga cable.  There are various 
multimedia and TV cards available ($200 and up) which display TV and
other crazy functions, but I would like to build one cheap. Does anyone
have specs for the VGA signals? I know there is a chip available which 
converts VGA-NTSC, but I'm looking for the reverse. Any hints before
I blow up my monitor?
Newsgroups: sci.electronics