HDTenEightyP/NetNews huggingface dataset:
From: cyberman@toz.buffalo.ny.us (Cyberman)
Newsgroups: sci.electronics
Subject: Re: 0to24v to -12to+12v c
Date: 10 Nov 92 01:24:56 GMT
X-Maildoor: WaflineMail 1.00r


   Seaney@engr.wisc.edu was espousing about '0to24v to -12to+12v conve',
   on [11-05-92  20:19] to All!
 Se> I'm in a bind.  The gradstudents before me goofed an purchased a 0 to
 Se> 24 Volt Power Supply (15Amps) to drive a Power OpAmp.  After close
 Se> inspection it became apparent the the OpAMp needs -12to+12V.  Since the
 Se> OpAmp drives a motor we need as much current as possible.

    Uh they didn't goof.  You see +-12v is no different to the
    motor as is 24 volts.  You need to make a virtual ground
    however.  If you don't need reversability there shouldn't be
    a problem.  Another easy solution is 2 0-24v supplies.  Be
    sure the power suppies can SINK current! :)

 Se> Is there a cheap way to convert 0 to 24 Volts (Floating) to -/+ 24
 Se> Volts.  The hard part seems to be the 15 Amp current requirement.

    Ussually is when you get above 10amps.  You could make your
    own :)

        Cyberman
... Life happens between 9am a 5pm for most poeple, no wonder there bored!
--- Blue Wave/QWK v2.10
From: cyberman@toz.buffalo.ny.us (Cyberman)
Newsgroups: sci.electronics
Subject: Re: 12 v -> 3v, 0.6 a
Date: 12 Nov 92 07:33:47 GMT
X-Maildoor: WaflineMail 1.00r


    Roderick Young entitled a message as 'Re: 12 v -> 3v, 0.6 a',
 RY> You car battery could put out as much as 14-15V sometimes.  Let's say
 RY> 13V. That means a (13-3 = 10V) drop across this linear regulator.  At
 RY> 600 mA, that's 6 WATTS.  It might work, if you use the TO-3 version,
 RY> and a very good heat sink.  You might consider putting a 8-ohm, 10-watt
 RY> resistor in series with the LM317 input to disspate some of the power.

    "good" idea

 RY> I actually used a (surface mount) LM317 to drop 12V to 5V, as less
 RY> current than you specify.  The chip got so hot, it melted its own
 RY> solder!

    How much current were you drawing?

                Stephen Cyberman@Toz.Buffalo.NY.US
             Mangled on Wed  11-11-1992  at 16:16:18
--- Blue Wave/QWK v2.10
                                                                                                              
Newsgroups: sci.electronics
From: johnh@macadam.mpce.mq.edu.au (John Haddy)
Subject: Re: IR circuit less prone to ambient light
Organization: Macquarie University, Sydney
Date: Sun, 8 Nov 1992 22:39:18 GMT

In article <nyarko.721072506@ee.ualberta.ca>, nyarko@ee.ualberta.ca (David Nyarko) writes:
|> 
|> Hi,
|> Could I have help (circuit diagrams etc.) for an Infra-Red
|> (IR) transmitter/receiver with a low tolerance to ambient
|> light. What I have in mind is the design of an obstacle
|> avoidance circuit. Sort of similar to the IR system used
|> in autofocusing cameras without the circuitry for
|> computing the distance.
|> 			David
|> 
|> email address: nyarko@bode.ee.ualberta.ca

I've come across a wonderful device from SHARP. It has, in a miniature 4 pin
package, a photodiode, amplifier, oscillator, SYNCHRONOUS DETECTOR and infra-red
LED driver. All you need to do is add a LED and give it some power.

The synchronous detection effectively eliminates ambient light interference
problems. Although no good for remote control type applications (you need wires
btween the receiver and detector), it is perfect for what you describe. It will
detect obstacles at a range of about 6" in reflective mode with no modifications.
You could add a current multiplier to the LED drive to get more range (it only
drives about 2mA at a 10% duty cycle at 10kHz - most LEDs will quite happily
accept 40mA or so at this duty cycle).

The part number is:	IS471F	(visible light cut-off resin) [IR only]

the catalogue also mentions:
			IS450	(transparent resin)
which comes in a weird package.

JohnH

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

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

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

----------------------------------------------------------------------------
Newsgroups: sci.electronics
From: mgc@unislc.uucp (Marc Christensen)
Subject: Re: Autodialer
X-Newsreader: TIN [version 1.1 PL6]
Organization: Unisys Corporation SLC
Date: Fri, 6 Nov 1992 16:08:57 GMT

Jim Karkanias (karkan@msdrl.com) wrote:
: Does anyone know of a public domain or shareware program that would let me
: assemble an arbitrary string of characters (representing those keys on a
: telephone) and send them to a modem?  I'd like to be able to programatically
: control a remote process; this process uses the phone as an interface...
: 
The problemI ran into and you probably will to was ...
the modems all expect a dial-tone before they will dial. No tone No Dial.
If the device "Answers" the phone then you will need to find a way around it.
Do the regular/Leased line switches on a modem disable this feature?

Making the modem dial is simple you need to send ATDT1234567890*# out the
serial port for a standard hayes modem. some brands will also handle A,B,C,D
codes like in a 12 digit pad.

Marc Christensen
From: msolomon@mitre.org (Moise Solomon)
Newsgroups: sci.electronics
Subject: Re: Radio Transmitter
Date: 5 Nov 92 21:36:27 GMT
Followup-To: sci.electronics
Organization: The MITRE Corporation

What frequency, bandwidth (data rate), modulation scheme?


In article <giri.1@umail.umd.edu>, giri@umail.umd.edu wrote:
> 
> I need to make a simple radio frequency transmitter with the following
> characteristics: range of a few miles, transmit on a single frequency, 
> energy derived from a button cell, CHEAP.
> 
> Any ideas on how I can build something like that?  Would a simple crystal
> oscillator do?  
> 
> Thanks for your help.  Please email me at gn1@umail.umd.edu

Standard Disclaimer Applies
Organization: Penn State University
Date: Thu, 5 Nov 1992 14:37:13 EST
From: <GNR100@psuvm.psu.edu>
Newsgroups: sci.electronics
Subject: Re: How good is RE descrambler
Distribution: na

        Not that I'm interested in building one, but how do those things work?

                                  Gordon Rogers
                                      gnr100@psuvm.psu.edu
Newsgroups: sci.electronics
Subject: Re: Info about Wireless (IR-) Headphones
Organization: Private
Distribution: world
From: markus@mbsys.in.sub.org (Markus Becker)
Organization: Private
Date: 4 Nov 1992 00:55:12 MET

Okay, TNX to all.
       Markus
-- 
markus@mbsys.in.sub.org (Markus Becker)
***************** Stop nazis in germany or stop germany at all******************
The opinions in the above message are my own and not necessarily held by others.
Remember: It's my life !!
Newsgroups: sci.electronics
From: schaerer@isi.ethz.ch (Thomas Schaerer)
Subject: Re: Would this blow my light?
Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH
X-Newsreader: TIN [version 1.1 PL6]
Date: Fri, 6 Nov 1992 07:39:37 GMT

Richard Banks (ah335@cleveland.Freenet.Edu) wrote:
: 
: 
: I need some help here.
: I have a small light I wish to use that is rated at 12V and
: much greater than 500 mW.  
: 
: Can I get away with powering it be a 18V line at 500 mW?
: Or could this possibly damage it from overheating or even
: blow it?
: 

If you want more lightpower you must take a bulb with more defined power.
If you increase the voltage, the lifetime will be very much reduced. For
longer life it's more better to power a bulp with a constant current source
than a voltage source. The advantage is no currentspikes by switch on.

Greeting Thomas
Newsgroups: sci.electronics
From: klimasewski@fccvde.enet.dec.com (My name is...)
Subject: 27512-->27128
Organization: Digital Equipment Corporation
Date:  6 NOV 92 15:02:25    


Can I convert a 27512 to a 27128 by lifting a pin from the circuit and
bring it to ground? I did this with a 27256 by lifting pin 27 and then
grounding it via pin 14.


                               Ken 
Newsgroups: sci.electronics
From: doherty@melpar (Kevin Doherty)
Subject: Re: TEC-200 film
Organization: E-Systems, Melpar Division
Date: Fri, 13 Nov 1992 14:39:22 GMT

agodwin@acorn.co.uk (Adrian Godwin) writes:

>I'm still trying to get the plotter to work before trying the direct-plot method, 
>but I see that several people have made double-sided boards using one or other 
>of these methods : how did you manage to get good registration between the two sides ?

  The best technique I've used is to etch and drill one side of the board
(the other side being covered by masking tape) then use the drilled holes
for alignment of the second side.  Masking tape on the etched side keeps
those traces intact when you etch the second side.

  Instead of drilling all the holes, I usually include four registration pads
at the extreme corners of the PCB so that if a little etchant leaks through
the hole from the side being etched, nothing critical is damaged.

From: tgg@otter.hpl.hp.com (Tom Gardner)
Date: Wed, 4 Nov 1992 10:47:21 GMT
Subject: Re: bandpass filter
Organization: Hewlett-Packard Laboratories, Bristol, UK.
Newsgroups: sci.electronics

For a high Q bandpass filter at 25Hz, a commutating capacitor filter mightbe
suitable. Note, this is not a "conventional" switched capacitor filter. The best
reference is in the Bell Systems Technical Journal for September 1960. The
first use for such a filter was in 1947, and it used a Strowager switch to 
notch out 60Hz.

Basic features:
	- centre frequency defined by digital clock
	- bandwidth defined by resistor and capacitor
	- comb filter response, so low-performance external bandpass filters
	  required to remove harmonics

A decade ago I built this:
	- center frequency 8kHz
	- 3dB bandwidth = 4Hz => Q = 2000
	- 30dB down at +- 300Hz
from
	- 8- way analogue multiplexer
	- 8 capacitors (10% tolerance)
	- one resistor (ditto)
	- digital clock
	- sallen+key bandpass filter


Newsgroups: sci.electronics
From: heyes@dadev.cebaf.gov (Graham Heyes)
Subject: telephone humm any solution...
Organization: Continuous Electron Beam Accelerator Facility
Distribution: sci.electronics
Date: Thu, 12 Nov 1992 14:34:13 GMT

The telephone cable at my home pops out of the ground and into
a box on the external wall. From there a single cable goes into
the house. I installed two telephones myself, one in the kitchen
and one in the bedroom. The one in the kitchen full of electrical
appliances is fine. The one in the bedroom has a terrible humm.
I tried swapping the handsets and the humm stays with the 
bedroom not with the handset. The only electrical equipment in
there is two table lamps. I have re-wired the wall outlet three
times and that has no effect. The strange thing is that some 
days there is no humm at all, other days you can't hear yourself
speak. I can find nothing wrong with the wiring, the one in the 
kitchen works fine so I haven't got the colors mixed up. 

	The only thing I can think of is that the cable in
the wall passes close to a power cable and that the humm is
pickup which occurs when some appliance in the house is operating. 
My best guess for a suspect is the refrigerator. 

	So is there any way to filter out a hum on a phone line
if so what do I have to get?

	thanks
		Graham Heyes

P.S. Oh, I callet the telephone company, for $50 they will send 
someone to LOOK at it, no promise that they will fix it, they say
they are responsible for the line as far as the house the rest is
up to me!
From: bk233@cleveland.Freenet.Edu (Jack W. Weinmann)
Newsgroups: sci.electronics
Subject: Re: Stereo schematic
Date: 7 Nov 1992 16:06:36 GMT
Organization: Case Western Reserve University, Cleveland, OH (USA)
Reply-To: bk233@cleveland.Freenet.Edu (Jack W. Weinmann)
NNTP-Posting-Host: slc10.ins.cwru.edu


In a previous article, schuch@phx.mcd.mot.com (John Schuch) says:

>In article <1992Nov2.234622.5585@athena.cs.uga.edu> mcovingt@aisun3.ai.uga.edu (Michael Covington) writes:
>>In article <1992Nov2.003710.1223@doug.cae.wisc.edu> greger@cae.wisc.edu (Greger Mike) writes:
>>>	I'm trying to find the phone number of a company called Sam's 
>>>photo-FAX.  They supply schematics for all types of electronic stuff.
>>
>>Order through any Radio Shack, or call 1-800-GAT-SAMS.
>>
>
>How much does a single PhotoFact folder cost? I usually buy the OEM
>service manual but these days they're going for about $30.00. If
>the Sams material is less expensive, I'd rather go thet way.
>
>John
>
Try your local library.  Most of the larger libraries carry a complete line
of Sams Photofacts.  In the Cleveland area both the Cleveland Public
Library and the Cuyahog County Library carry Sams.

Hope this helps.

Jack
Newsgroups: sci.electronics
From: mal2n@fulton.seas.Virginia.EDU (Matt Leonard)
Subject: A Call for Electronic Project Catalogues 
Followup-To: mal2n@virginia.edu 
Organization: University of Virginia
Distribution: sci.electronics
Date: Wed, 11 Nov 1992 04:09:41 GMT


I am a second year EE engineer and I am looking for a fun project to build
over Christmas break.  Anyone have any catalogues that sell complete kits
of FUN INTERESTING and EDUCATIONAL projects to put together?  I'm open to
all suggestions.....

Please Email me with 1-800- numbers and any comments / suggestions that
you may have.....
	thanks!
	mal2n@virginia.edu
From: sehari@iastate.edu (Babak Sehari)
Newsgroups: sci.electronics
Subject: Re: Creating sci.semicond
Date: 12 Nov 92 20:20:51 GMT
Organization: Iowa State University of Science and Technology, Ames, Iowa.
Originator: sehari@vincent2.iastate.edu

---

I submitted a formal request for creation of this "Wild" newsgroup.
There are some procedural steps that we should follow. The first
step of this is under way. We should get the first formal posting
for creation of this network wide and "wild" newsgroup soon.

                      With highest regards,
                           Babak   Sehari


--
From: mpaul@unlinfo.unl.edu (marxhausen paul)
Newsgroups: sci.electronics
Subject: Re: HELP: non-intrusive current sensor
Date: 6 Nov 1992 13:41:50 GMT
Organization: University of Nebraska--Lincoln	
Distribution: usa
NNTP-Posting-Host: unlinfo.unl.edu

mbattist@magnus.acs.ohio-state.edu (Mark A Battisti) writes:

>I need a current sensor (On/OFF) for a standard 110 AC line which
>gives a logic signal (5V).  I tried running the live line through a coil
>which I ripped out of a small transformer and then amplify the coil
>response w/op amps but I could not get this to work.

Get yourself a toroid core - it's just a little donut of ferromagnetic
material - and have your "hot" line make a few loops through it.  Run 
a second wire through it a bunch of times and you've got a toroidal 
transformer that ought to put out a signal proportional to the 
current on the 110 AC line.

--
paul marxhausen .... ....... ............. ............ ............ .......... 
 .. . .  . . . university of nebraska - lincoln .  . . .. . .  .. . . . . . . .
 .     .    .  .   .     .   .  .    .   .  .   .    .   .  grace .   .    .  . 
   .         .       .      .        .        .      .        .   happens .     
Newsgroups: sci.electronics
From: nyarko@ee.ualberta.ca (David Nyarko)
Subject: IR circuit less prone to ambient light
Organization: University Of Alberta, Edmonton Canada
Date: Fri, 6 Nov 1992 17:55:06 GMT


Hi,
Could I have help (circuit diagrams etc.) for an Infra-Red
(IR) transmitter/receiver with a low tolerance to ambient
light. What I have in mind is the design of an obstacle
avoidance circuit. Sort of similar to the IR system used
in autofocusing cameras without the circuitry for
computing the distance.
			David

email address: nyarko@bode.ee.ualberta.ca
From: orf@skool.ssec.wisc.edu (Leigh Orf)
Newsgroups: sci.electronics
Subject: Re: 12 V -> 3V, 0.6 A
Keywords: Sony, adapter, car, portable CD
Date: 11 Nov 92 16:44:17 GMT
Reply-To: orf@ssec.wisc.edu (Leigh Orf)
Organization: Atmospheric & Oceanic & Space Sciences Dept., UW Maidson, WI

In article <1992Nov10.161358.5509@ms.uky.edu>, msunde01@mik.uky.edu (Mark 
Underwood) writes:
>
>I hate to throw a bucket of cold water on everything, especially in a  
>newsgroup full of people who just LOVE to design their own gadgets, but  
>wouldn't it be easier to get a cigarette-lighter power adaptor for about  
>$10 or so from an electronics store like (dare I mention the R-S phrase?)  
>or somewhere, or, heaven forbid, get the one the manufacturer recommends  
>and save your warrantee??  Caveat:  I tried to find a SONY adaptor for my  
>SONY discman, and have yet to find a place that can keep them in stock  
>long enough . . ..  I ended up with the R-S model, and rigged a "pigtail"  
>plug adaptor using the plug from my A-C adaptor (since the plug on SONY is  
>non-standard) and fixed it so I could switch the pigtail from the AC to  
>the DC adaptors.  It works, though I admit it took all the fun out of  
>devising a solution . . ..
>

It is kindof eerie that this thread is going on... this is the first time I have
read sci.electronics, and I decided to read the old messages first before making
my post about how to make an adapter from 12V (car battery) to 6V 400mA for my
Sony Discman. Weird. Anyway, the reason for wanting to build one myself is
simple: Sony has you by the balls - an adapter costs $38 and I called the
distribution center in Minneapolis this morning and they are on backorder (more
than three weeks before they will come in). Like Mark says, the plug is
non-standard (as is the amperage, at least for most other portables). Gee, I
wonder why Sony does this??? (grump growl complain). I was going to stop by
Radio Shack later today... did you say that they have the adapters with the
correct polarity, voltage, and amperage, but the wrong size plug? I can live
with that ..... in fact I was considering the exact same fix that you devised
(cutting the AC adapter plug & using it for both via some sort of simple
connector).

leigh

                                     -*-
        * '76 Saab 99 * Sprecher Amber * Phish * Radio Netherlands *
     "Black things billowing forth with the power...
| /_|/_|_| /\|>|_                  ...of ten billion butterfly sneezes"
|_\ |\/| | \/|\|                                       - Moody Blues
Newsgroups: sci.electronics,misc.forsale.computers.pc-clone,misc.forsale.computers.d
From: tomh@wes.on.ca (Tom Haapanen)
Subject: Re: 486 CPU KOOLERS FOR SALE
Organization: Waterloo Engineering Software
Date: Fri, 06 Nov 1992 10:54:38 GMT

bketcham@stein.u.washington.edu (Benjamin Ketcham) writes:
> Temperature-induced failures?  I don't think so.

A few years ago, I had my AST 386/20 fail due to an overheating CPU; and
after it had failed once, it failed again and again very easily.  Now,
it failed after running all day in a non-air conditioned environment at
over 30C (90F) ambient ...  I have never seen it happen in a "normal"
office or home environment.

But, yes, a CPU fan would probably have saved my AST, so  you might want
to consider getting one if you run in extreme heat.

[ \tom haapanen    "i don't even know what street canada is on" -- al capone ]
[ tomh@wes.on.ca                   "trust the programmer" -- ansi c standard ]
[ waterloo engineering software      "to thine own self be true" -- polonius ]
From: drp40@cd.amdahl.com (Doug Puchalski)
Newsgroups: sci.electronics
Subject: Re: Cable TV Rules
Date: 5 Nov 92 04:36:50 GMT
Reply-To: drp40@cd.amdahl.com
Organization: Amdahl Corporation, Sunnyvale, CA

In article <1992Nov3.113716.836@cmkrnl.com>, jeh@cmkrnl.com writes:
>
>Personally I see no reason why cable companies can't live by the same rules the
>phone company does:  You can do your own inside wiring and they can't say a
>thing as long as you don't steal service nor interfere with other people's
>service. 

Really?  They won't live by it unless they have to!  They get away with it
because they can!!

-- 
Doug Puchalski						   Death to all smileys
drp40@cd.amdahl.com
dpuchals@engin.umich.edu
From: curt@oasys.dt.navy.mil (Curt Welch)
Newsgroups: sci.electronics
Subject: Re: Phone line monitor
Date: 9 Nov 92 18:22:37 GMT
Reply-To: curt@oasys.dt.navy.mil (Curt Welch)
Organization: Carderock Division, NSWC, Bethesda, MD

In sci.electronics, kharstin@MtHolyoke.edu (Ken Harstine) writes:
>I would not recommend that you tie any portion of
>this circuit to ground, as this would unbalance the phone line, and might
>cause distortion of the sound.

This reminds me of a problem I had.  I tried to use an oscilloscope once
to look at a phone line and some phone interface circuits I was playing
with.  Hooking up the scope caused a large hum to be introduced in the
circuit, which prevented me from making any useful measurements.

So, my question.  How do I use a scope to look at a phone line?  Do I need
an isolation transformer between the power and wall outlet?  Or is there
some type of probe I could buy that would provide the needed isolation?

Curt Welch
Newsgroups: sci.electronics
From: markz@ssc.com (Mark Zenier)
Subject: Re: lease/rent spectrum analyzer ?
Organization: SSC, Inc.,  Seattle, WA
Date: Wed, 04 Nov 1992 18:45:43 GMT
X-Newsreader: TIN [version 1.1 PL6]

urbina@novax.llnl.gov wrote:
: Does anyone know where I could possibly lease or rent an spectrum analyzer ?
: especially near or around the Bay area. With the outrageous cost of an SA,
: It's pretty damn near impossible for hardware hackers like me to be able to buy
: one.  I have access to one at work, but I want to use one at home for a part
: time business. Preferably one that sweeps from DC to around 5 GHZ and portable.

Companies like Electro Rent and Leasametric usually charge about 
10 percent of purchase price per month.  But they also sell
almost new stuff off lease at prices proportional to the 
possibility of leasing it out again.  

A good place to get a couple of year old microcomputer development
stuff, but on a less fashion conscious instrument like a spectrum
analyzer, not as good a deal.

Listed in the Electronics Testing Equipment in the Yellow Pages.

Mark Zenier  markz@ssc.wa.com
From: hleaves@gems.vcu.edu
Newsgroups: sci.electronics
Subject: Needed: 9 pin RS232 specs
Date: 7 Nov 92 22:37:44 -0400
Organization: Medical College of Virginia

I'm trying to find out the pin assignments for the standard 9 pin RS232 port
connector used on many PC's and laptops. I've got the 25 pin assignments, but
I've had a hard time finding the 9 pin equivalent. If somebody could post or
mail me the specs I would greatly appreciate it.

Thanks.
-- 
*******************************************************************************
** Hugh L. Eaves                      ** Internet: hleaves@ruby.vcu.edu      **
** Medical College of Virginia        ** Bitnet: hleaves@vcuruby             **
** Department of Human Genetics       ** Voice: (804) 371-8754               **
***************** All non-incendiary communication welcome! *******************
Newsgroups: sci.electronics
From: eystein@smyril.fi.uib.no (Eystein Dugstad)
Subject: BOOk WANTED about computers in measurements and control
Organization: University of Bergen, Norway
Date: Thu, 12 Nov 92 10:32:11 GMT

I'm looking for a more advanced book about the same topic as a book I  
have. The book I have is: "Computers in systems for measurements and  
control" by Dag Bjorklof.

Thanks in advance

Eystein Dugstad
University of Bergen, Norway