HDTenEightyP/NetNews huggingface dataset:
From: kehoe@netcom.com (Thomas David Kehoe)
Newsgroups: sci.electronics
Subject: Can I use 1 power supply instead of 2 9-volt batteries?
Keywords: cable, RF, A/V
Date: 15 Oct 92 18:03:50 GMT
Distribution: na
Organization: Netcom - Online Communication Services (408 241-9760 guest)

My op-amp prototype uses two 9-volt batteries, to supply
+9 volts, -9 volts, and ground.  It requires new batteries
after 5-10 hours of use, and I have a 9-volt power supply
(that plugs into the wall).  Replacing the +9 volts battery
with the power supply will be easy.  Is there an easy way
to replace the -9 volt battery?

Would an inverting op-amp do this?  That would be easy.
The alternative is to use op-amps that just require +9 volts
and ground.  I could so this too.
-- 
"Why my thoughts are my own, when they are in, but when they are out
they are another's." - Susannah Martin, hanged for witchcraft, 1692.
Thomas David Kehoe          kehoe@netcom.com         (408) 354-5926
Newsgroups: sci.electronics
From: clarke@acme.ucf.edu (Thomas Clarke)
Subject: Re: Need small tool to cut pcb board
Organization: University of Central Florida
Date: Thu, 8 Oct 1992 15:23:18 GMT

Rough edges left by a saw blade can be smoothed by a carbide
router bit - the kind with a guiding wheel used for trimming
formica.  Clamp the board to a surface with a striaght edge and
route the edge smooth.
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
From: gmw1@cunixa.cc.columbia.edu (Gabe M Wiener)
Newsgroups: sci.electronics
Subject: Re: Theremins
Date: 10 Oct 92 03:21:27 GMT
Reply-To: gmw1@cunixa.cc.columbia.edu (Gabe M Wiener)
Organization: Columbia University

In article <1992Oct9.184635.23089@b30.ingr.com> medin@catbyte.b30.ingr.com writes:
>
>I was just sort of fooling around with making one of these with
>gate oscillators. In the process, I discovered that Popular
>Electronics had produced the plans for a Theremin back in the 70's
>too. The article is not in my archives.

That's Radio-Electronics, actually.  It's around on microfilm at any
Engineering library.  For some reason I recall 1978 being the year.

Electronic Hobbyist or some such put out a "Digital Theremin" schematic
based on one chip...I don't remember which.  I built one of these about
four years ago.  Still have it somewhere.

Bob Moog (of synthesizer fame) is apparently manufacturing theremins
with MIDI output now...


--
Gabe Wiener - Columbia Univ.     "This 'telephone' has too many shortcomings 
gmw1@cunixa.cc.columbia.edu       to be seriously considered as a means of 
N2GPZ in ham radio circles        communication. The device is inherently of
72355,1226 on CI$                 no value to us." -Western Union memo, 1877
Newsgroups: sci.electronics
From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Subject: Re: high voltage insulation breakdown
News-Software: VAX/VMS VNEWS 1.41    
Reply-To: frank@rover.uchicago.edu
Organization: Joint Center for Radiation Therapy
Distribution: usa
Date: Mon, 12 Oct 1992 15:58:00 GMT

In article <1992Oct9.153551.12624@infonode.ingr.com>, brantley@infonode.ingr.com (Dwight D. Brantley) writes...
>I am experiencing a breakdown of the insulating properties of a high
>voltage wire which seems to be related to several possible causes.  ...
>The anode wire insulation is breaking down either under the grommet or
>right at the edge of it resulting in high voltage arcing to the metal
>box.  The arcing leaves a hole in the insulation and can occur either
>inside the box or outside but is always associated with the grommet.

	Many hears ago, we did some study on some breakdown problems similar
	to yours. What we generally found was that if unexplained breakdowns
	were occurring it was because:

	For a wire in free space, with air at ground and reasonably humid
	air, (not the sahara,) you got a constant voltage gradient across
	the insulator.

	When you did anything (in our case, it was bending back the outer
	braid of a coaxial cable on itself, and attaching a ground wire,)
	you ended up with a 2 or 3 capacitor circuit, consisting of the
	various items there. In your case, the grommet is forming part of
	the 2-capacitor divider, (one cap is the material of the grommet,
	the other the material of the insulator of the wire.) What often
	happens is that high voltage goes across the grommet, causing
	corona, which causes ozone, which breaks down the chemical properties
	of the insulator, which breaks down, which shorts out.

	Main suggestion. Best insulator is air, other than that, you should
	have a hight voltage grommet. They look more like donuts with a thin
	membrane in the hole, and are maybe 1/2 or 1 inch in diameter, to
	reduce high voltage gradient.

   Frank R. Borger - Physicist    __       Internet:  Frank@rover.uchicago.edu
Michael Reese - Univ. of Chicago |___      Phone : 312-791-8075 fax : 567-7455
  Center for Radiation Therapy   | |_) _   If you've got them by the balls,
                                   | \|_)  their minds and hearts will follow.
    "Birthplace of Softball"          |_)  Charles Colson - Nixon aide
From: bender@oobleck (Duke of Canterbury)
Newsgroups: sci.electronics
Subject: Re: 16 bit wide EPROMS??
Date: 12 Oct 92 23:34:04 GMT
Reply-To: bender@oobleck.eng.sun.com
Organization: SPARK's R US
NNTP-Posting-Host: oobleck
X-Newsreader: Tin 1.1 PL3

rwc@ius4.ius.cs.cmu.edu (Randy Casciola) writes:
: 
: 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.
			[...]
: anything would work since the code could be downloaded into fast
: SRAM on powerup.

If you're going to download the code to RAM, why not just use a commonly
available 8-bit EPROM that's twice the capacity that you need?  Or does your
process need to read it's boot code from this EPROM as well?  Does your
processor have a mode that allows it to do 2 8-bit fetches from program
memory sequentially?  If so, maybe your processor could boot from the 8-bit
EPROM, copy whatever code needs to be copied to fast 16-bit RAM, then start
executing out of 16-bit RAM space.  This assumes that your processor can be
told to start doing 16-bit fetches...

mike

--
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    Grashopper, you have been many years in the training, and I grow old,
    expecting the day when I receive the SIGXCPU, and _exit this world.
    I see that you are ready.
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Date: Wed, 7 Oct 1992 19:20:07 GMT
Subject: Re: Pullups needed for high-impedence TTL inputs?
Organization: Hewlett-Packard, Fort Collins, CO, USA
Newsgroups: sci.electronics


> I know pullups are required for CMOS inputs if the inputs can go into
> high-impedence.  Does the same hold true for TTL?  What about HCT?
> 

Gee, Jeremy, third question today! :-)

I think you are a bit confused - INPUTS do not "go into high impedance,"
outputs do - specifically, such things as "tristatable" TTL outputs.
(CMOS inputs ARE high impedance, and you sometimes see resistors on CMOS
inputs connected to TTL outputs, but that's because CMOS levels for "1" and
"0" are "farther apart" than the typical TTL output, so pull-ups and pull-downs
are needed to make sure the CMOS device sees the right level.)

Pull-ups or pull-downs are needed on any tri-state output when you want to
make certain that the inputs on that line will definitely see a valid state
when all drivers (outputs) are tristated - if such resistors aren't present,
the line will "float" at an intermediate level.  A TTL input will *usually*
read a "floating" line as a "high" (logical 1), but this ISN'T guaranteed.
(On the other hand, ECL inputs ARE guaranteed to be pulled LOW internally,
so be careful about making assumptions about undriven lines!)

Putting pull-ups and pull-downs on inputs is always a good idea if there is
any time when the line can be put into a state such that these inputs aren't
being actively driven.  Choose the size of the resistor according to how
many inputs are on that line (there's no need for a resistor at each input!),
and what the drive requirements are for inputs in that technology.  Pull-DOWNS
are sometimes also used in the case of an input that needs to be tied low,
but which may also need to be overridden (driven to the high state) for test
purposes.


Bob Myers  KC0EW   Hewlett-Packard Co.      |Opinions expressed here are not
                   User Interface Tech. Div.|those of my employer or any other
myers@fc.hp.com    Fort Collins, Colorado   |sentient life-form on this planet.
From: ehare@arrl.org (Ed Hare - KA1CV)
Newsgroups: sci.electronics
Subject: Re: RFI/EMI shielding of a plastic box
Date: 13 Oct 92 09:45:37 EDT
Organization: American Radio Relay League

One good way to shield a plastic box is with conductive paint. One source
of this is:

GC-Thorensen catalog # 10-4807
1801 Morgan St
POB 1209
Rockford IL 61102-1209
815-968-9661

I have one caution -- make sure the surface is clean and that the paint
will stick well! If the paint flakes off, the conductive flakes will
wreak much havoc in the circuit they are trying to shield! 

73 from ARRL HQ, Ed


-----
Ed Hare, KA1CV                  ehare@arrl.org
American Radio Relay League
225 Main St.
Newington, CT  06111            There is no limit to what you can 
(203) 666-1541 - voice          accomplish if you don't care who
ARRL Laboratory Supervisor      gets the credit. - Harry S Truman
RFI, xmtr and rcvr testing  
-----
From: maufr@csv.warwick.ac.uk (Mr N E Plum)
Newsgroups: sci.electronics
Subject: Re: Any reason for GND around perimeter of PC Board?
Date: 10 Oct 1992 01:42:56 +0100
Organization: Computing Services, University of Warwick, UK
NNTP-Posting-Host: clover.csv.warwick.ac.uk

> I have looked at a some examples PC boards and have noticed that some
> have a thick ground trace around the perimeter of the board.  Any
> reason for this?

Maybe to help avoid shorts to a (grounded) metal case.
Nicolai
-- My opinions can be so wierd, no-one wants to share them --
From: kharstin@MtHolyoke.edu (Ken Harstine)
Newsgroups: sci.electronics
Subject: Re: Looking for (e(e))prom programmer info
Date: 9 Oct 92 01:49:29 GMT
Organization: Mount Holyoke College
X-Newsreader: Tin 1.1 PL5

JDR has a number of prom programers for sail.  The manufacturer is
Modular Circuit Technology.  The model I have is the MOD-MEP as well as
the required interface card.  This model has been replace by the MOD-MEP-1A.
The also have a low cost version called the MOD-EPROM.  The all include an
interface card for and IBM compatible, and include software.  I have only had
mine a month now.  It is quite fast for both programing and data
transfer.  And easy to use as well.  So far I have only used it to program
27C256s, however it will do up to 27512s.  The
cost is $199.95 for the MOD-MEP-1A, and $129.95 for the MOD-EPROM.

They are available from:

	JDR Microdevices
	2233 Samaritan Drive
	San Jose, CA  95124
	Phone (408)559-1200
Newsgroups: sci.electronics
From: cdacosta@ee.ubc.ca (DA COSTA ANTONIO L)
Subject: Smith Chart
Organization: University of BC, Electrical Engineering
Date: Thu, 8 Oct 1992 06:04:31 GMT

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!

...Tony


+------------------------------------------+----------------------------------+
| Antonio L. da Costa (cdacosta@ee.ubc.ca) |  EEEE 2     U   U  BBBB    CCC   |
| Electrical Engineering                   |  E          U   U  B   B  C   C  |
| University of British Columbia,          |  EEE        U   U  BBBB   C      |
| Vancouver, British Columbia, Canada      |  E          U   U  B   B  C   C  |
| "Shit happens."                          |  EEEE        UUU   BBBB    CCC   |
+------------------------------------------+----------------------------------+
From: tocherd@ul.ie
Newsgroups: sci.electronics
Subject: Help - DEC VR100 monitor
Date: 12 Oct 92 13:11:32 GMT
Organization: University of Limerick, Ireland

Hi,

I've aquired a VR100 monitor from a VAXstation 100m system. I believe its a 
high res B/W system but I don't know anything else about it. Can anyone help 
with the following;
Line rate,
Frame rate,
signal levels for the three BNC connectors -( no, not RGB!)

There are silly icons which imply seperate line/field/video signals.

Thanks,

David Tocher, EI2AMB
Dept of Maths
University of Limerick
Ireland
From: Jason.Goga@mailbox.bison.mb.ca (Jason Goga)
Newsgroups: sci.electronics
Subject: HV transformer sources?
Date: 08 Oct 92  14:47:00 CST

 >>Could you explain, what practical use a Tesla coil has? Other than:
 >>- Scaring little children
 >>- popping small animals
 >>- lighting up flourescent tubes a few meters away
 >>- getting the attention of the FCC
 >>
 >>-Jason

 > Why does everyone assume that when someone wishes to experiment with
 > high
 > voltage, pulsed current, etc. that the product of such an experiment is
 > always
 > used in a negligent fashion?

It was sarcastic humour, lighten up. After all, those are the things people tend to do with the tesla coils I've seen. Oh, forgot to mention;
- Making a lot of wee little holes in a sheet of paper.
- Making them V-shaped things, that look really cool.
- Disabling all the computers at a science-fair.

 > High voltage and other projects are always
 > good
 > for teaching about electricity.
True, I can remember a story about an electronics teacher who was teaching his class about the dangers of high-voltage and said never to stick a screwdriver into a TV (while power was on). He just happened to have said tool in his hand and a TV nearby and managed to zap himself good while he was speaking.

I'm pretty sure they [the students] were pretty careful after that!

 > If you can not think of any uses for High Voltage Tesla Coils other than
 > the
 > ones you stated above, then YOU shouln't be contributing your comments.

Take it with a bit of salt please! I asked because I didn't know and you still haven't given me any examples of what a tesla coils would be used for.

-Jason

---
 * Origin: C.A. - FrontDoor (1:348/207)
Organization: Queen's University at Kingston
Date: Thu, 8 Oct 1992 08:41:47 EDT
From: Iain D. Holness <HOLNESSI@QUCDN.QueensU.CA>
Newsgroups: sci.electronics
Subject: Re: Help! My CD player sk-sk-sk-sk-skips
Distribution: usa

     I too would like to know the name of this book, as the mail
  bounced back for me as well.

     Even an ISBN number would be appreciated :)

     Iain
Newsgroups: sci.electronics
From: mpeter@vision.ethz.ch (Martin Peter)
Subject: source for pessure sensors
Keywords: pressure sensor, nova
Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH
Date: Wed, 7 Oct 1992 16:04:02 GMT

can someone give me an adress in the US, where I can order 
pressure sensors from "Nova Sensor" in single quantities ?

Thanks

Martin  mpeter@vision.ethz.ch


--
------------------------------------------------------------
Martin Peter                   e-mail: mpeter@vision.ethz.ch 
ETH Zuerich                    tel:    41 1 256 5286
Computer Vision Group          fax:    41 1 261 3429
Newsgroups: sci.electronics
Subject: Re: Telephone interface
From: hilbig_t@qis.dofasco.ca
Date: 8 Oct 92 08:58:52 GMT
Organization: Dofasco Inc, Hamilton, Ont. Can.
Nntp-Posting-User: hilbig_t

In article <1992Oct2.130056.17508@phx.mcd.mot.com>, hbg6@phx.mcd.mot.com (John Schuch) writes:
> dIn article <1agi51INNc58@usenet.INS.CWRU.Edu> at847@cleveland.Freenet.Edu (Jeff Hunsinger) writes:
>>
>>This has got to be an FAQ, but I just read about 100 subject lines
>>and didn't find it. I am trying to hook up a DTMF decoder (SSI202)
>>and a voice synthesizer (amplified with an LM386) to a telephone line.
>>The DTMF decoder works fine so long as I don't hook up the amp.
>>Here's my current set-up:
>>----Cap--- 600:600 ohm matching transformer-> amp -> ssi-202
>>                                           <- Amp -< voice synth.
> 
> 
> 
> Possibly I don't understand what your doing but what is the purpose
> of the amplifier in line with the SSI202? The 202 should work fine
> just capacitivly connected to the 'safe' side of your isolation
> transformer. Maybe a more detailed ASCII-schematic (ASCIImatic ? :-)
> would make it clearer.
> 
> John
> 

This problem is typical of a modem that uses one pair of lines for incoming
and outgoing signals.  The demodulator circuit only wants to hear the
incoming signal and not the outgoing signal of the modulator circuit.  To
do this, a hybrid circuit is placed in front of the input circuit (in 
your   case, this will be the DTMF decoder) that eliminates the outgoing
signal.



	Vspeech  >-----------------------
	from LM386			|
					|
					|
		     R1 10K		|
		-----/\/\/----|		|
		|	      |		|
		|	   /| | R2 10K	|
		|	 / -|---/\/\/---|
		|      /    | 		\
     Vdtmf <----------<     |		/  R3 600ohm
     to SSI202	       \    | 		\
			 \ +|-----------|
			   \|		|
					|  600:600 Transformer
					|
					--) || (------
					  ) || (      To Telephone line
					  ) || (
					  ) || (------
					  |
				         GND


The speech voltage at the transformer is halved by the 600 ohm resistor; you
may have to increase your output gain.

The transmitting speech voltage will across the matching resistor R3 will
appear as a common mode signal to the op-amp and effectively eliminated. 
You can work this out mathematically by considerring the transformer to be
a voltage source (say Vin) in series with a 600 ohm resistor.  The voltage
Vdtmf works out to equal Vin, regardless of the Vdtmf output signal.

The circuit assumes a perfect match of 600 ohms across the spectrum.  This
is impractical but should not be a problem for your project.  Your DTMF 
decoder may pick up a little bit of the speech signal, but it shouldn't
cause any false results.


Good luck, Tom Hilbig

 
 
 
 

-- 
Thomas Hilbig,
hilbig_t@qis.dofasco.ca                 Telephone:  (416) 544-3761
My mail is sick these days, if you get a failure, send it to
hauser_s@eis.dofasco.ca

Newsgroups: sci.electronics
From: pvr@wang.com ()
Subject: Re: Looking for a good PD Circuit Board Layout Program
Organization: Wang Labs, Lowell MA, USA
Date: Thu, 15 Oct 92 17:55:19 GMT

A2HQC@CUNYVM.BITNET writes:

>Like the subject title says I would like a GOOD PD PCB layout program. Any
>suggestions would be appreciated. Thanks.

	Try PADS.   It is a freeware version of a commercial product.
It has limits to the size of the design that it will handle but
is otherwise complete.


These files are available via anonymous FTP from WSMR-SIMTEL20.ARMY.MIL
(192.88.110.20) or mirror sites OAK.Oakland.Edu (141.210.10.117),
wuarchive.wustl.edu (128.252.135.4), ftp.uu.net (137.39.1.9),
nic.funet.fi (128.214.6.100), src.doc.ic.ac.uk (146.169.3.7) or
archie.au (139.130.4.6), by e-mail through the BITNET/EARN file
servers, or by uucp from UUNET's 1-900-GOT-SRCS.  See UUNET file
uunet!~/info/archive-help for details.

Directory PD1:<MSDOS.CAD>

PADSLIB.ZIP   B  488615  920212  PADS library for PADSPCB.ZIP and PADSLOG.ZIP
PADSLOG.ZIP   B 1081636  920212  PADS Logic schematic capture CAD program
PADSPCB.ZIP   B 1036461  920212  PADS PCB (printed circuit board) layout pgm

--
>>>>>>>>>>>> Peter Reilley ..... pvr@wiis.wang.com ..... KA1LAT <<<<<<<<<<<<<
                     Well, that about says it.
Newsgroups: sci.electronics
From: cole@soldev.tti.com (Randy Cole)
Subject: Re: Electronics magazines & Mail order brides
Summary: A puzzle...
Keywords: none
Organization: Citicorp-TTI
Distribution: all
Date: Thu, 8 Oct 1992 17:00:01 GMT

This thread reminded me of the following ad that has been running 
in the Personal Announcements section of the LA Times classifieds
for at least six months:

        About us, Technology Princess
        Our true colors are recorded:
             Blue-Brown-White-
        White-Grey-Brown-Green-Red-
         Blue-Yellow. Just listen.

it should be easy for readers of this group to figure it out.
BTW, I'm NOT the person who is running the ad.

Randy Cole

(let me know if you're stumped, I'll send you a hint without much
resistance)
From: aw0g+@andrew.cmu.edu (Aaron Wohl)
Newsgroups: sci.electronics
Subject: Re: new PIC microcontroller
Date: 8 Oct 92 03:41:07 GMT
Article-I.D.: andrew.4ep1tHu00WA141KUVs
Organization: Systems Group 97, Carnegie Mellon, Pittsburgh, PA

I just ordered the paralex programmer with the upgrade.  However I
havn't got a line on actually getting a chip yet...  Let  me know if you
find a source.  I will let you know what the paralex package looks like.
Aaron
From: bender@oobleck (Duke of Canterbury)
Newsgroups: sci.electronics
Subject: Re: RockWell design
Date: 15 Oct 1992 00:29:16 GMT
Organization: SPARK's R US
Reply-To: bender@oobleck.eng.sun.com
NNTP-Posting-Host: oobleck
X-Newsreader: Tin 1.1 PL3

CT61@music.mus.polymtl.ca ("Duc-Nghiep VO") writes:
: Can somebody here send me all doc on the Rockwell chipset ?.

Well, let's see - Rockwell probably has many thousands of chipsets (maybe
10's or 100's of thousands) - would you like all of the docs on all of them?

: and their address too.

some things that I would try:

	1. dial 1-800-555-1212, ask for Rockwell Corporation
	2. dial 1-408-555-1212, ask for Rockwell Corporation
	3. dial 1-YAC-555-1212, ask for Rockwell Corporation
	4. find a Rockwell databook and look up the phone number
		and address in there

    Note: YAC means Your Area Code

mike

--
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    Grashopper, you have been many years in the training, and I grow old,
    expecting the day when I receive the SIGXCPU, and _exit this world.
    I see that you are ready.
From: mdsp_ltd@uhura.cc.rochester.edu (Pooch)
Newsgroups: sci.electronics
Subject: Voltage to PWM suggestions?
Date: 11 Oct 92 00:53:38 GMT
Organization: University of Rochester - Rochester, New York

I'm looking for a quick and dirty (and very cheap) way to convert
an input voltage between 0 and 10 vdc to a Pulse Wiedth Modulated
square wave with a duty cycle between 0 and 100%

This output will be used to drive a solid state relay, which will be driving
an incidesent lamp.

Please E-mail suggestions to 

mdsp_ltd@uhura.cc.rochester.edu

Thanks in advance.
Marc. 

-- 
+-------------------------------------------------------------------------+
|    Marc D. Spencer, C.E. WRUR-FM   | Technology is a way of organizing  |
|   mdsp_ltd@uhura.cc.rochester.edu  |  the universe so that man doesn't  |
|                                    |  have to experience it    -Frisch  |
Newsgroups: sci.electronics
From: pierson@cimcad.enet.dec.com (Dave Pierson)
Subject: Re: Filtering noise from a Van de Graaf
Organization: Digital Equipment Corporation
Date: Fri, 9 Oct 1992 13:20:55 GMT

>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.

	That's a potent machine.  It may or may not be "filterable".  If the
	destruction is caused by mains carried spikes, fine.  However there will
	be an electric field of nontrivial amount set up, then collapsed, with
	each discharge.  This will couple direct to nearby devices, and may be
	large enough (for this machine) to do direct damage.  (say, roughly,
	200KV/Meter initial field strength.  non trivial.)

thanks
dave pierson			|the facts, as accurately as i can manage,
Digital Equipment Corporation	|the opinions, my own.
146 Main St			|I am the NRA.
Maynard, Mass		01754	pierson@msd27.enet.dec.com
"He has read everything, and, to his credit, written nothing."  A J Raffles
Newsgroups: sci.electronics