HDTenEightyP/NetNews huggingface dataset:
From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Newsgroups: sci.electronics
Subject: Re: serial to parallel converter ( as in rs232 -> centronics )
Date: 15 Oct 92 22:13:00 GMT
Reply-To: frank@rover.uchicago.edu
Organization: Joint Center for Radiation Therapy
News-Software: VAX/VMS VNEWS 1.41

In article <93243@netnews.upenn.edu>, george@mech.seas.upenn.edu writes...
> 
>'feels like' a pretty trivial thing to make, with the box and
>connection ports being the most costly components.

	Assuming you are going to do the right design, which is not only
	doing serial to parallel, but handling handshake at the rs232 end,
	(either ctl-s/ctl-q, or DTR line, and maybee even ACK/NAK codes,)
	Also assume you are making a universal box (both way conversion.)
	Also you must control ready/busy, paper out, fault lines at the
	centronics end, (at the bare minumum.) Further assume you will want
	to handle number of bits and possible parity the RS232 end.

	1/ You really need a micro to do the handshaking, parity calculations
	   handling number of data bits, etc.

	2/ You need a prom to go with the micro. (Forget about the programmer
	   and debug/programming costs for now.)

	3/ You need several RS232<>TTL converters.

	4/ You need a UART for the serial-parallel part.

	5/ You need 5v to +/-12 v converter chip.

	6/ You need a baud rate generator, (for your serial/parallel part.)

	7/ You need a circuit board.

	8/ You need 1 DB25 and 	1 centronics socket

	9/ You need misc wire-wrap sockets, or circuit board capabilities.

	Add it all up, and (quantity one,) you'll probably pay around $100
	for just the parts.

	And THEN YOU STILL HAVE TO BUILD IT.

	As an aside, I've been doing stuff like this for years, and am still
	amazed that:

	A/ People say "it only takes a few parts,' and when they actuall cost
	   up ALL THE PARTS, they slap their foreheads and say "I never thought

	B/ Nobody ever counts the cost of their own labor. My own rule of
	   thumb is that semi-custom, kit, hand-made etc the labor cost is
	   at least as much as the parts, and probably is closer to 2times
	   for projects at the $100 level.

	As an aside, why didn't you spend a little more and get the right
	kind of printer? ;-)

   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   | |_) _   I guess I must have had New England
                                   | \|_)  ancestors away back and inherited
    "Birthplace of Softball"          |_)  some of their staunch and rugged
					   fear of the police. - O. Henry
Newsgroups: sci.electronics
From: mylai@cs.uh.edu (Ming-Yung Lai)
Subject: Motorola's S19 conversion
Organization: Computer Science dept.,  Univ. of Houston (Main Campus)
Date: Fri, 9 Oct 1992 13:32:33 GMT

 Hi, Is there a PC program that can convert Motorola's S19 format to
 Intel's HEX format, and vice versa.
 Thank you for your time.
From: dhi00@ccc.amdahl.com (mofo )
Newsgroups: sci.electronics
Subject: re: 25 ohm coax
Date: 13 Oct 92 15:10:52 GMT
Reply-To: dhi00@juts.ccc.amdahl.com (mofo )
Organization: Amdahl Corporation, Sunnyvale CA

i dont understand jurriaan's statement concerning my claim below:

>>if the two branchs are equal in length, the signals travel
>>and meet at splice B.  this gets a little tricky.  a wave front
>>traveling along the south branch would approach splice B and
>>see an approx. 17 ohm impedance (50 and 25 in parallel).  the
>>reflection generated from a 50 to 17 ohm mismatch is about
>>1/2 the incident wave so at the splice, the signal is reflected
>
>No, the reflection coefficient at B isn't 1/2, if you assume that
>the signal sees a 17 ohm impedance. In that case 50-17/(50+17) would
>be reflected.
>
>>back down the south branch with voltage 1/2 v.  as it happens,
>>the other branch has provided a boost of 1/2 v as well at precisely
>>the same time and therefore a signal of v is created at splice
>>point B (works the same from either branch).
>


as you said yourself, 50-17/(50+17) would be reflected.  work that
out; you get 33/67, roughly 1/2 as i quoted earlier.  the figure
works out.

d
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Newsgroups: sci.electronics
Subject: Bad customer relations; was: Re: archive server for pa
Date: 7 Oct 92 15:23:16 GMT
Article-I.D.: athena.1992Oct7.152316.26018
Organization: AI Programs, University of Georgia, Athens

In article <gate.2Z37RB1w165w@toz.buffalo.ny.us> cyberman@toz.buffalo.ny.us (Cyberman) writes:
>

> MZ> In case you've missed the trend in the past decade or so, towards
> MZ> "Closer Customer Relationships", "Just in Time", and the rest of that
> MZ> package,  "They" don't want a lot of little customers, just big
> MZ> ones.  The money for sales support is going to go to the the things
> MZ> that make money.  And if this means ignoring a lot of small customers 
> MZ> in favor of a few big ones, well ...

>    all around.  What happens when the "little" guy becomes big?
>    And they DON'T want to deal with them?  What goes around
>    comes around alienated companies are "entities" run by
>    poeple.  If you jerk the company you jerk the poeple.  This
>    means those poeple WILL not deal with the company ussually
>    again.  I've seen MANY poeple do this.

That is why Maxim, Dallas Semiconductor, and Mini-Circuits are going to
rise up and give the big companies some stiff competition.

It's been done before.  Remember a little software company called Borland?



-- 
:- 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: Jason.Goga@mailbox.bison.mb.ca (Jason Goga)
Newsgroups: sci.electronics
Subject: The Communicator
Date: 08 Oct 92  15:02:06 CST

 >>I'll leave comments on the quality of
 >>RS radios to those with direct experience.

 > "Quality" and "Radio Shack" are two concepts not often found in close
 > proximity. I don't know about their two-way radios, but the RS weather
 > radio I've got has much poorer reception than the promotional freebie
 > weather radio my dad has. Strictly off the record, the local NOAA
 > station said they get the most complaints about a "weak signal" from
 > owners of RS models.

RS does tend to sell poorer quality stuff, given. However since they've given up being 'creative' with thier computers, they've almost become competitive (scarey!). I'll let you know how I find my laptop after a few weeks of use, and we'll see if they're changing. A re-issue of the COCO3 would be kinda cute, as there's a lot a jabberin about how cool a machine it was. Oh well, sorry for being off-topic, but it needed saying.

-Jason

---
 * Origin: C.A. - FrontDoor (1:348/207)
Newsgroups: sci.electronics
From: markz@ssc.com (Mark Zenier)
Subject: Re: TV->RGB hookup?
Organization: SSC, Inc.,  Seattle, WA
Date: Thu, 08 Oct 1992 04:23:14 GMT
X-Newsreader: Tin 1.1 PL3

an938@cleveland.Freenet.Edu (George II Lenzer) writes:
: Is it possible to extract an RGB signal from a 
: composite video signal?  I would like to use my monitor for double
: duty with a VCR.  Any suggestions would be appreciated.

"NTST - RGB Converter", Jim Harrigfeld, Radio-Electronics, October 1990.

I built one of these for a friend and was quite impressed with the
quality of the kit (circuit board and parts).  Better than average
for your typical magazine project.

You need a monitor that does the 15750 Hz Horizontal rate.  And
analog RGB.  We tested it out on a IBM CGA monitor.  It worked, but
it looked like special effects.

Harmonic Research, Inc.
193 Villanova Dr.
Paramus, NJ  07652

(201) 652-3277

Mark Zenier  markz@ssc.wa.com  

Newsgroups: sci.electronics
From: johnh@macadam.mpce.mq.edu.au (John Haddy)
Subject: Re: why is one prong on plug wider than the other?
Organization: Macquarie University, Sydney
Date: Thu, 15 Oct 1992 23:40:39 GMT

In article <BvvG7J.2tA@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes:
|> In article <1992Oct9.012645.17219@athena.cs.uga.edu> mcovingt@aisun3.ai.uga.edu (Michael Covington) writes:
|> >One side of the line is grounded to the earth so that the potential between
|> >line and ground will never be excessively high; this is a safety measure...
|> 
|> However, don't confuse the "neutral" side of the line with ground.  Sure,
|> it's grounded -- at the pole, or at best where the wires enter the building.
|> But a simple application of Ohm's Law will tell you that when there is
|> current flowing through that wire, especially when there's a lot of current
|> involved, points elsewhere on that wire are *not* at ground, not quite.
|> In my old apartment (in a high-rise beehive) I measured neutral at
|> something like 10V with respect to ground, which is certainly enough
|> to be dangerous, given the amperage available.

...to equipment, not people. The internal resistance of the human body is such
that 10V won't cause any harm if through extremity contact (i.e. you don't apply
the volts in the middle of open heart surgery!).

The IEC is in the process of defining a power reticulation system specified at
50Vac as a Safety Low Voltage. 50V has been chosen because it appears to be the
maximum safe voltage usable under non-extraordinary conditions.

John Haddy

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

      |  _  |_   _   |_|  _   _|  _|              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: mdk@col.hp.com (Mark Keisling)
Subject: Re: Max699 ( what is this for? )
Date: Fri, 9 Oct 1992 21:29:24 GMT
Organization: HP Colorado Springs Division

geb1@ra.msstate.edu (Granville Barker) writes:
> I was just wondering what a MAX 699 IC is used for?
> 
The MAX699 is a reset/watchdog timer part.  It monitors the +5V supply
and generates a reset pulse for the system.  The watchdog timer will
pulse its output if it doesn't detect any activity on its input for
more than a second.

Mark.
From: Jason.Goga@mailbox.bison.mb.ca (Jason Goga)
Newsgroups: sci.electronics
Subject: Who has surplus night-vision stuff?
Date: 08 Oct 92  15:20:32 CST

 > Does anyone know of a good source of surplus night-vision
 > equipment?  I'm interested in both IR and Starlight units.
 > However, I must admit that I'm looking for the lower-priced
 > used stuff.

 > The economy being what it is... :-)

 > Thanks!

 > Gary

An aquaintance of mine (Bruce Walzer) picked up a IR-R camera (NTSC but very high res) from:

Halted Specialties
3500 Ryder St
Santa Clara California

These were the COHU cameras, and need external sync but he was very pleased with it. Cost is something like $30.

-Jason

---
 * Origin: C.A. - FrontDoor (1:348/207)
From: CCEB001@UTXVM.CC.UTEXAS.EDU
Newsgroups: sci.electronics
Subject: Re: Filtering noise from a Van de Graaf
Date: 16 Oct 92 20:40:23 GMT
Article-I.D.: UTXVM.16882CE67.CCEB001
Organization: The University of Texas at Austin

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 resets computers and destroys chips in some equipment on the same mains.
> I have tried a few comercial flters with no success.
>
A Van de Graaf generator is built for the purpose of creating high
voltage static, emp, and electrical transients.  Playing with one in
the vicinity of computers, stereos, tvs, vcrs, or any other sensitive
electronic equipment is ill advised.
 
The question is roughly equivalent to asking, "I have built a large
blowtorch.  How may I play safely with it around gasoline?"
It may be possible to take enough precautions, but the main
precaution to take is to just say "No!"
 
Analog tube gear was leading edge at the time these generators were
and generally recovers from transients quickly.   Solid state
digital is not like that.
 
Mike.Coyne@utxvm.utexas.edu
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: 25 ohm coax cable
Date: 14 Oct 92 20:19:38 GMT
Article-I.D.: hpfcso.7480129
Organization: Hewlett-Packard, Fort Collins, CO, USA

> 
> A signal arriving at junction A sees an impedance of 25 ohms. So at that point no
> reflections occur. But what is the impedance which the signal travelling through
> the lower cable sees arriving at junction B? It looks to me that it surely isn't
> 50 ohm, so at that point reflections are produced. 

No, it's not 50 ohms, but the important thing is what's happening overall -
you must keep in mind that in this scheme, we are assuming the simultaneous
launch of identical signals down matched lengths of 50 ohm cable - the
resulting effect at either end of the circuit you drew is the same as if
the "paired 50s" were replaced by a single length of 25 ohm cable, which is
all that was originally required.

Are the signals *within* either 50 ohm cable the same in voltage and
current amplitudes as that within the single 25 ohm cable?  No.  But that's
NOT the point of this.

> One other porblem I have, is that all mailers just replace a coax cable by
> an inductance and a capacitance:
> 
>         --- L ---
>                  |
>  Z -->           C
>                  |
> 
>            1              L
> Z = jwL + ---  <> root ( --- )  !!!!!
>           jwC             C
> 
> Any comments?
> 

This is NOT what the posters who argue from an "inductance and capacitance"
standpoint are saying; remember, these are *distributed* parameters, meaning
that an "infinite" series of circuits such as the one you drew above makes
up the model for the cable (assuming no losses).  If you try to solve for
the input impedance of such a network*, it WILL come out to SQRT(L/C), which
says that the char. impedance depends solely on cable geometry and dielectric,
and DOES NOT vary with frequency.  (Frequency comes into the formul only if
losses cannot be ignored, at which point the calculation gets somewhat
messier.) 

* - Try it; remember that we're talking about an infinite series of such
"LC" combinations, so what you're solving is

	Z = jwL + [(1/jwC) || Z]

Solve for Z.


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: steuer@clam.rutgers.edu (robert Steuer)
Newsgroups: sci.electronics
Subject: Need Op-Amp Help.
Date: 7 Oct 92 18:29:39 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

I just finished an Electric Circuits Lab and one of the circuits
involved an op-amp where the op-amp had its two bipolar power supply
connections, and a signal generator was feeding a sine wave into the
non-inverting input of the op-amp.  Then, a direct connection was made
from the output to the inverting input and the gain was measured.  It
was found that there was no change in the gain.  Then, the same
circuit was used but instead of the piece of wire going from the
output to the inverting input a 27k resistor was used and the gain
remained the same although one would have thought it would
decrease.(At least I did anyway!)  Is this because there was no second
resistor that would normally have gone from the inverting input to
ground?  That is all I can come up with because the formula to
calculate gain is Afb=(Rf)/(R1) + 1 for closed loop gain.
Can anyone verify that my assumption is correct or not?
                                  Thanks, Rob
-------------------------------------------------------------------------------
| Robert Steuer               Internet: steuer@clam.rutgers.edu               |
| Rutgers University          Amateur Radio: KF2EK@N3FOA.#EPA.PA.USA.NA       |
-------------------------------------------------------------------------------
From: dennis@ccu.umanitoba.ca (Doug Dennis)
Newsgroups: sci.electronics
Subject: VCR COPY PROTECTION - MACROSCRUBBER KIT???
Date: 16 Oct 92 03:06:06 GMT
Organization: University of Manitoba, Winnipeg, Manitoba, Canada
Originator: dennis@ccu.umanitoba.ca

Hi!

About two years ago there was a thread on this newsgroup about vcr copy 
protection and someone mentioned a company that sold a 'macrosrubber' kit.
I phoned the company to get the details and I seem to remember that it was
about $30 - $35.00.  I have lost this information and would appreciate it if
someone could tell me the company's name, address and phone number.
Please e-mail me if you can help.

Thanks in advance

Doug Dennis
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Date: Wed, 7 Oct 1992 19:11:13 GMT
Subject: Re: Can despiking caps be connected to a central ground?
Organization: Hewlett-Packard, Fort Collins, CO, USA
Newsgroups: sci.electronics

> Do despiking caps need to go directly between the VCC and GND inputs
> of a given IC, or could they go between VCC of the IC and some central
> 
> ground location, or even another IC's ground, for that matter?
> 

"Despiking" caps?  I'll assume you mean "decoupling" or "bypass" caps, rather
than something specifically intended to filter noise coming in from elsewhere.

In this case, the best method is for the cap to be placed between power 
and ground planes of a multi-plane PC board, with the shortest possible
leads (chip caps are great!).  This is to reduce the lead inductance, and
so keep the self-resonant frequency of the cap as high as possible.  If you
do not have separate power and ground planes available (such as in a wire-wrap
board or a simple one or two-layer PCB), the cap should be between Vcc and
ground such that the leads are again as short as possible.  This may mean
placing the cap between the Vcc pin of one IC and the ground of one in the
next row - the important thing is not that a cap be "associated with" a
particular IC, but that you have sufficient distributed capacitance across
the power and ground "grids."  Also, put a small electrolytic (a few 10s of
uF or so) across the power and ground near the point where power enters the
board, to help take care of low-frequency noise from outside the circuit.


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.
Newsgroups: sci.electronics
From: gmeiers@edsi.plexus.COM (Garrett Meiers)
Subject: Re: variable speed/pitch cd decks modification?
Organization: Enterprise Data Systems Incorporated, Appleton WI
Date: Thu, 15 Oct 1992 05:05:34 GMT

drp40@cd.amdahl.com (Doug Puchalski) 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 asked this question on the net a year or two ago and someone said
>that Denon had a player out there with a pitch control on it.  I never
>saw one though.  Perhaps it was a "studio" type player?  I say that because
>I doubt they would market such a player for normal home usage--there just
>wouldn't be a demand for it.

I have seen many decks that have pitch/speed controls..  But I do not
want to pay the price for one!  The demand isn't in the home, but out on
the road with mobil club Dj's that need to do beat-matching, etc..


------
gmeiers@edsi.plexus.com	                          Garrett Meiers
Newsgroups: sci.electronics
From: rbanksjr@nyx.cs.du.edu (Richard E. Banks Jr.)
Subject: Soldering using flux!
X-Disclaimer: Nyx is a public access Unix system run by the University
	of Denver for the Denver community.  The University has neither
	control over nor responsibility for the opinions of users.
Organization: Nyx, Public Access Unix at U. of Denver Math/CS dept.
Date: Tue, 13 Oct 92 19:49:43 GMT


I was more than half way finished with a project that I was building
before I realized how much better solder works when you use flux.

I was trying to solder a solid core hookup wire to a connector on a
jack but it would just not stick, until I used the flux and it
soldered very easily.

Anyway, what is flux made of and why does it work so well?

Thanks. Rich Banks.
From: pauls@trsvax.tandy.com
Newsgroups: sci.electronics
Subject: Re: 16 bit wide EPROMS??
Date: 15 Oct 92 19:43:00 GMT
Nf-ID: #R:cs.cmu.edu:2:trsvax:288200023:000:194
Nf-From: trsvax.tandy.com!pauls    Oct 15 14:43:00 1992


Most Japanese firms (Toshiba, Fujitsu, Hiatachi) have X 16 EPROMS. Fujitsu
has LCC EPROMS which are tiny (but expensive!). THe Tandy VIS CDROM player
uses a Toshiba 512K X 16 EPROM (OTP) in it.
Newsgroups: sci.electronics
From: feg@cbnewsb.cb.att.com (forrest.e.gehrke)
Subject: Re: Thunderstorms
Organization: AT&T
Distribution: na
Date: Wed, 7 Oct 1992 19:03:30 GMT

In article <1992Oct7.152434.11480@col.hp.com> cab@col.hp.com (Chris Best) writes:
>Anyway, not much earlier than all this, I had decided to unplug all
>the equipment in the stereo closet, the antenna and power to the
>TV/VCR area, and power strips to my PC's (including the phone line
>to an internal modem).  Good thing, as it turns out.  A little
>while after the big strike, I tried to call a friend to see what
>it was doing out his way, and used the cordless phone just to be
>safe.  No such luck - it was out of commission, since I hadn't
>thought of the phone lines to the PHONES.  In taking it apart later,
>I found a transistor that had exploded, and black marks under the PCB
>right where the phone connecter is soldered.  Also, the power cube
>that plugs into the wall to power the phone was shot.  I don't 
>know if the surge went out from the phone, or a surge in the power
>lines did it, since it didn't damage another phone (also electronic) 
>that was plugged into the same outlet and a phone jack just six 
>wire-inches away.
>
>I am convinced that a surge came in on the phone line, and expect
>that one also came in on the power lines - not from a direct hit
>on either, but just from the antenna effect all that wiring offers.
>

This should be a reminder to people with PC's.  So many have
surge protectors in their power line to the PC but fail to
put one on the phone line (if connected to a modem as part
of the PC installation).  Via the phone line there is a more
direct path into the expensive innards of the PC, such as
the motherboard, than there is via the power line.  The latter
is more likely to destroy something in the switching DC power
supply--probably less than a $100 cost.

Forrest Gehrke feg@dodger.att.com  k2bt

Newsgroups: sci.electronics
From: steve.miller@rose.com (steve miller)
Subject: ZX80 Adapter Pinout
Organization: Rose Media Inc, Toronto, Ontario.
Date: Wed, 14 Oct 1992 06:37:53 GMT
X-Gated-By: Usenet <==> RoseMail Gateway (v1.70)


Date Entered: 10-14-92 01:29

P(L Does anyone remember a small computer put out by Sinclair
    called ZX80? I was rummaging through my electronic junk pile
    and found the little guy and I thought I might try to re-use
    it as a controller. There is a large connector in the back
    which looks like it might have been used as an expansion slot,
    I was wondering if anyone would happen to know what the port
    is for and what the pinout is?

    I had one of those, and what we had in the slot was a memory
    expasion module. Which increased the RAM 16K! But sorry I have no
    idea of what the pinout is.
---
   OLX 2.1 TD   I live in a quiet neighborhood, they use silencers
   RoseMail 2.00 : Usenet: Rose Media - Hamilton (416) 575-5363
Newsgroups: sci.electronics