HDTenEightyP/NetNews huggingface dataset:
From: jmorriso@ee.ubc.ca (John Paul Morrison)
Subject: (epoxy) Re: "The Glob" Atari 2600 processors ???
Organization: University of BC, Electrical Engineering
Date: Wed, 23 Dec 1992 21:40:36 GMT

In article <1h3dv3INN53h@rave.larc.nasa.gov> kludge@grissom.larc.nasa.gov (Scott Dorsey) writes:
>In article <BzJExG.40D@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>>Apart from the possibility of deducing the chip type by studying the rest
>>of the circuit, the only way to find out is to get the epoxy off.  That
>>is Not Easy.  The stuff is completely inert as far as the usual run of
>>solvents etc. are concerned.  It can be done, using truly vile chemicals,
>>but it's not the sort of thing you want to try unless you really know
>>what you're doing.
>
>You can do it with DMSO.  I have reverse-engineered a number of potted
>modules by soaking them in DMSO.  Note that DMSO will also remove the
>epoxy board underneath if you aren't very careful about it, and will also
>(in the case of more complex modules) remove the coating from resistors
>and capacitors making them difficult to read values from.

What's DMSO? (I wan't to say dimethylsulfoxide, but I'm just guessing from 
a small inventory of knowledge)


>
>DMSO is readily available at your local health food store.  Note that the
>solution of epoxy in DMSO is lethal and can be absorbed through the skin.
>Use with proper ventilation, eye and skin protection.  Very, very nasty
>stuff.

Can you be more precise? Does th epoxy, DMSO stuff have a MSDS (material
safety data sheet, I don't know what OSHA in USA calls it)

>--scott


-- 
__________________________________________________________________________
 John Paul Morrison                     |  
 University of British Columbia, Canada |  
 Electrical Engineering                 |   .sig file without a cause
 jmorriso@ee.ubc.ca              VE7JPM |  
________________________________________|_________________________________
Newsgroups: sci.electronics
From: jasa@dalton.inesc.pt (Jose Antonio Soares Augusto)
Subject: Re: Grounded Emitter Amplifier Query
Organization: INESC, Lisboa Portugal
Distribution: sci.electronics
Date: Wed, 30 Dec 1992 18:45:15 GMT


You forgot something in yuour analysis: THE SATURATION CURRENT Is IS
TEMPERATURE DEPENDENT. I have my copy of H&H (1st ed.) at home but I
checked in Sedra&Smith "Micr. Circuits" (4th ed.), page 126 where is
said that Is doubles for each 5 C degree rise in temperature.

Moreover, the change in Vbe (-2.1mV/degC) is supposed to occur at
CONSTANT emitter current, which is not the case. In the Common
emitter-grounded amplifier you have

Vbe=R_2 V_CC / (R_1 + R_2)

supposing that I_B<< than the current in the resistors. Now you have

I_C=I_S exp(Vbe/Vt)   (I_S and Vt known at 300 K)

if at 300 K you increase the temperature to, lets say, 305 K, the
value of Vt increases 1.67% relative to the 300 K value. However,
I_S DOUBLES (according to Sedra&Smith) and you have:

I_C = 2 I_S exp(Vbe/1.0167 Vt)  (I_S and Vt are the 300 K value)

The Vbe is CONSTANTLY BIASED if Ib << than the current in the
resistors and so you notice that, considering at 300 K that Vbe=0.65 V
and that Vt=25mV

 I_C (305 K) / I_C (300 K) = 1.3 

Raising in fact the Ic current. As you have seen, the key facts are
the large increase in Is and the fact that the Vbe value remains
approximately constant.


	J. Augusto
From: samir@Warren.MENTORG.COM (Samir Agarwal)
Newsgroups: sci.electronics
Subject: broken switch on answering machine
Date: 29 Dec 1992 12:56:38 -0500
Organization: Mentor Graphics Corp. -- IC Group
Distribution: world
NNTP-Posting-Host: samir.warren.mentorg.com

Hello all,

I have this Radio Shack Duofone (tad-241) answering machine that has a
knob on the rear to adjust the delay before the answering machine kicks
in.

This knob is broken and the answering machine never picks up.

I opened up the machine and found that this thing looks like a potentiometer
(but again it could be anything, I am not electronics savvy).

Is there any way to fix this thing? I don't mind if the machine picks up
immediately instead of several rings.

Thanks,

 - Samir


--
         Samir K. Agarwal                |       Mentor Graphics
         samir@samir.warren.mentorg.com  |       IC Group
         uunet!sdl!samir                 |       15 Independence Blvd.
    	 MABELL   : (908) 580-0102 x722  |       Warren, NJ 07059
    	 Voicemail: (800) 437-2230 #5803 |


-- 
"If anything can go wrong, it will" -- Murphy's Law
 "Nothing is so bad that it can't get worse" -- Gattuso's extension to above
Newsgroups: sci.electronics
From: jmorriso@ee.ubc.ca (John Paul Morrison)
Subject: Good way to prototype analog circuits?
Organization: University of BC, Electrical Engineering
Date: Sun, 3 Jan 1993 23:17:33 GMT


Does anyone want to share their tips on prototyping analog circuits?
Specifically: sensitive, high gain circuits; RF circuits etc.

These kind of circuits work well with PC boards with ground planes,
but are there any simple, easy to make changes, techniques for this?
Are there any pre-made boards with a ground plane, and holes with solder
contacts on them?


thanks
-- 
__________________________________________________________________________
 John Paul Morrison                     |  
 University of British Columbia, Canada |  
 Electrical Engineering                 |   .sig file without a cause
 jmorriso@ee.ubc.ca              VE7JPM |  
________________________________________|_________________________________
Newsgroups: sci.electronics
From: dc@stars.gsfc.nasa.gov (Dave Cottingham)
Subject: Re: Origin of 'BNC'
News-Software: VAX/VMS VNEWS 1.4-b1  
Keywords: BNC CONNECTORS HISTORY QUESTION
Reply-To: dc@cobi.gsfc.nasa.gov
Organization: NASA/GSFC-Laboratory for Astronomy and Solar Physics
Date: Tue, 29 Dec 1992 20:36:00 GMT

In article <BzBMr3.E7K@world.std.com> dlowe@world.std.com (Miller Lowe) writes:
>We have a raging debate going on at work with some folks beliving
>that BNC stands for British Naval Connector.... While others(Like
>me) say Bayonet-Neill-Concelman.

Just to add one more piece of misinformation, when I was a grad student
it was common knowledge that it stood for Berkeley Nuclear Corporation,
the idea being that said company (if it ever existed) invented it and
popularized it by making a lot of equipment that used it.  But you know
how far you can trust common knowledge.

 - Dave Cottingham
   dc@cobi.gsfc.nasa.gov
Newsgroups: sci.electronics
From: philip@mentorg.com (Philip Peake)
Subject: Re: Charging a battery
Date: Tue, 22 Dec 1992 23:31:38 GMT
Organization: Mentor Graphics
Keywords: 
Followup-To: 

In article <1992Dec22.190416.26827@ucsu.Colorado.EDU>, barr@tramp.Colorado.EDU (BARR DOUG) writes:
|> I notice when charging my car battery that the amps goes up to about
|> 5 when battery is dead and gradually goes down to nothing as the battery
|> is charged. How does a battery charger sense this? The internal resistance
|> of the battery? (but no, becuase that goes down as the charge goes up,
|> doesn't it?). What sort of sensing circuit is used to reduce the amperage?
|> Anyone know?

None at all.

What you basically have is:

	---[int R1]--o---[int R2]--
        |                         |
        |                         |
       (v) Charger               ---
        |     14v               ----- Battery
        |                         |
        |                         |
        -------------o-------------

Your charger, with no load applied, outputs about 14 volts,
it has some internal resistance (int R1), so as you draw current from
it, some voltage is dropped across that resistance.

A fully charged battery is about 13.2 volts, and if slightly
overcharged, about 14 volts. The battery also has some
internal resistance (int R2), but usualy negligable compared to the
internal resistance of the charger.

An uncharged battery has a voltage of about 10.8 volts.

So, we can get an idea of the value of R1 - since you say that
an uncharged battery draws about 5 amps:

	14 - 10.8 = 3.2;  3.2/5 = 0.64 ohms

So, your charger internal resistance is about 0.64 ohms.
When you draw 5 amps from it, there will be 3.2 volts
dropped across it, so the voltage across the battery will
be 10.8 volts.

As the battery charges, the voltage across it increases.
When it is up to 12 volts, the charging current will
be:

	14 - 12 = 2; 2/0.64 = 3.125 amps

When the battery is fully charged, the current will be:

	14 - 13.2 = 0.8; 0.8/0.64 = 1.25 amps.

Once fully charged, the voltage across the battery rises
quickly, and once it is at 14 volts, the current is:

	14 - 14 = 0; 0/0.64 = 0 amps

Philip

Newsgroups: sci.electronics
From: gsulliva@enuxha.eas.asu.edu (Glenn A Sullivan)
Subject: Re: Clocks
Summary: Building a LOW-JITTER 14MHz oscillator
Organization: Arizona State University
Date: Sat, 2 Jan 1993 05:52:11 GMT

flux@sys6626.bison.mb.ca (John Kamchen) writes: .........
> What I need is a 14Mhz clock that doesn't jitter the length of a video 
> line.  
> An LM1881 provides the syncs, and the clock should be stable as possible.
> Looks like this
> --____----------------------------------------------
> _-____-_-_-_-_-_-_-_-_-_-_-_-  and so on  this is the 14Mhz clock
>  
Does not jitter over the length of a video line! Assume less than 5 nanosec
jitter out of 62Usec line length. This gives about 5 picoseconds jitter per
cycle. Basically we need an oscillator with LOW PHASE NOISE, since phase
noise is Frequency Modulation (PM and FM are related via integration).

You need a high-Q tank circuit that IS >>>> NOT OVERDRIVEN <<<<. 
So use a transistor oscillator, with biasing adjusted to keep the signal
swings well away from saturation or cutoff. And find a way to keep the
maximum signal from building up and up, which would distort.
With "linear" amplification that is barely
barely adequate to oscillate, any off-frequency energy (phase noise)
actually gets ATTENUATED on each pass around the tuned loop.

HP uses a nice trick in the LC oscillators for their 3330 synthesizer:
(1) they use a differential pair to form the oscillator, with the emitter
resistor providing a very stable current
(2) the oscillator is LOADED intentionally with a resistor, so that as
the signal swing increases as stored energy increases, eventually the
resistor is absorbing any additional energy dumped into the tank. Thus the
operating swing is fairly well defined. 

Since HP hangs this resistor upon the tank circuit, and resistors themselves
generate noise, you want a low value resistor to avoid directly inducing
lots of Boltzmann/Johnson/thermal noise (phase noise) into the tank. So use
series capacitors ( 1.1*C in series with 10*C) with the damping resistor
hanging across the 10*C capacitor. 

Just when you thought analog design was totally passe', and that DSP
methods would replace all!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Allen Sullivan
analog design expert, video engineer, RF trainee, system analysis practitioner,
DSP algorithm inventor, and hiker to where 300 foot waterfalls .....fall.

Arizona in the winter!
From: washer@sequent.com (Jim "Throw it over the wall" Washer)
Newsgroups: sci.electronics
Subject: How to control speaker output (squelch)?
Date: 27 Dec 92 21:11:56 GMT
Article-I.D.: sequent.1992Dec27.211156.2292
Organization: Sequent Computer Systems, Inc.

I have built a little dtmf controller that will 'turn on' when it receives
a specific set of dtmf codes. I want to use this to keep a speaker on my
radio quiet until the codes are received. I do not know what method is
best for switching the speaker. 

Should I use a double throw relay, and switch between the speaker and an 8ohm
resistor?

Should I terminate the speaker output at an audio amp (lm386?) and switch the
amp?

Other ideas?

tia
 - jim    washer@sequent.com
Newsgroups: sci.electronics
From: simon@sco.COM (Simon Tooke)
Subject: Flywheel Batteries
Organization: SCO Canada, Inc.
Date: Fri, 25 Dec 1992 13:27:10 GMT


This discussion about flywheel batteries in cars reminded me of the first
time I heard of this idea. but with a slight twist.  In the 70's Popular
Science had a page or two about buses using flywheels to store energy 
when they brake, and release it when they accelerate.  Thus, the flywheel
would _not_ be used for steady state driving, but would store and supply
peak energy; for a public transit vehicle this could be significant.

This would put a different slant on those 6 hp cars; shove small motors
in them and let the flywheel take up the slack for uphill/downhill and
sto/start driving.  Of course, it works best for stop/start city driving,
and would only be dead weight when turning the vehicle on in the morning.
I believe this idea was meant for electric vehicles (easier to transfer
energy around), and initial daily startup would be at a garage with
some tool or process that ensured the lack of a spinning flywheel wouldn't
hinder getting up to speed the first time.  Note that once you are up
to speed, the flywheel might as well stop; it'll be spun up again during
decelleration.

I probably have all the details wrong, but I just thought I'd toss this out.

-simon

===============================================================================
Simon Tooke  (not speaking for) SCO Canada, Inc.         Voice:  (416) 922-1937
....!scocan!simon             simon@sco.com                Fax:  (416) 922-2704
130 Bloor St. West. Suite 1001, Toronto, Ontario, Canada  M5S 1N5




Xref: sparky sci.electronics:21515 sci.energy:6428 rec.autos:30460
From: wb8foz@skybridge.SCL.CWRU.Edu (David Lesher)
Newsgroups: sci.electronics,sci.energy,rec.autos
Subject: Re: Flywheel batteries as EV power source
Date: 24 Dec 1992 01:28:20 GMT
Organization: NRK Clinic for habitual NetNews abusers - Beltway Annex
Reply-To: wb8foz@skybridge.scl.cwru.edu (David Lesher)
NNTP-Posting-Host: skybridge.scl.cwru.edu

Others said:
# It doesn't sound like you have been listening either.  In the event of
# a catastrophic failure, gasoline burns, it does not explode.  The energy
# contained in the tank is released over a period of 15 to 20 minutes.
# 
# The flywheel will try to dissipate it is energy over a span of milliseconds.

Errr,
Try telling the three people who burned to death in the tanker/
multi-car crash at the I 270/Beltway intersection that it is ok that
gasoline burns over 15-20 minutes. That may be true, but they are still
dead, regardless of how long their remains cooked.
--
A host is a host from coast to coast..wb8foz@skybridge.scl.cwru.edu
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
Newsgroups: sci.electronics
From: digdug@iastate.edu (Doug V Tran)
Subject: Re: [* NINTENDO PG PINNOUT... *]
Organization: Iowa State University, Ames IA
Date: Mon, 28 Dec 1992 14:52:26 GMT

In <BLV6VB11w165w@sys6626.bison.mb.ca> baden@sys6626.bison.mb.ca (baden de bari) writes:

> 
>       There is also a little black box that comes with the pg... are the 
>pinouts any different??
> 
>        >>Baden<<

I think the Jul 90'(could be June) issue of Byte has the specs of the
 powerglove.
It shows you how to interface the Powerglove to the serial port of a
PC.  Also, you can get some nifty virtual reality software that uses
the Powerglove.

later,
doug




Newsgroups: sci.electronics
From: nagle@netcom.com (John Nagle)
Subject: Re: lasers/collimated light i
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Distribution: sci
Date: Thu, 31 Dec 1992 07:28:35 GMT

"glen mead" <glen.mead@canrem.com> writes:
>jlange@radian.uucp (John Lange) writes:
>JL>In nightclubs I have recently seen light effects which apparently
>JL>use bright red, green, and blue lasers which are modulated with
>JL>mirrors (I think) to do interesting things like project color
>JL>images on a wall.  The red could be a simple He-Ne laser, but what
>JL>about the green and the blue?  

      I suspect you are seeing a xenon lamp fronted by a color wheel and
mirror galvonometers, all computer controlled.  These are now a common
disco lighting gadget.  The beam is collimated well enough that it looks
like a laser beam, but it isn't.  Look for leakage of white light from
the unit.

					John Nagle
Newsgroups: sci.electronics
From: paul@grafted.UUCP (james caldwell)
Subject: Re: CD Virus?  :-)
Organization: GRAFTED, Central Indiana's Usenet BBS 317-881-4369
Date: Mon, 21 Dec 92 01:19:37 CST

schuch@phx.mcd.mot.com (John Schuch) writes:

> I have a Fisher CD player which worked well for 4 years. About two
> weeks ago, it developed a problem. When you insert a disk, it spins
> it up and then flashes "DISK" on the display. It's acting like it
The most common failure is lubrication of the laser pickups slide rails
the laser has to move similar to a floppy drive head. You'll need to
order this from manufacturer or find where they recommend to get it
There are different types of lube.

Next is the spindle motor this can cause skipping or the symptom you
described. Depending on the model you may or may not be able to 
buy the motor seperately. EX: Sony sells only the whole mech assemply
for 125.00 when the motor should only cost 7.00 or so.
 
The last is alignment, you'll need a manual, service bulletins, test
equipment and training. Good luck

Try calling the manufacturer and finding out where you can ship the
unit to for "Factory Service". They are usually cheaper than the
local factory authorized service, and if they cannot fix it they can
replace it .


--
james caldwell
The Grafted Branch BBS
317-881-4369
internet: paul@grafted.UUCP
uucp: ..!uunet!grafted.UUCP!paul
 = = Grafted Branch BBS (317) 889-6997 2 Gig on-line = =
Xref: sparky sci.electronics:21381 sci.energy:6357 rec.autos:30317
From: stead@skadi.CSS.GOV (Richard Stead)
Newsgroups: sci.electronics,sci.energy,rec.autos
Subject: Re: Flywheel batteries as EV power source
Date: 22 Dec 92 16:09:27 GMT
Followup-To: alt.flame

In article <1992Dec21.193621.12001@microware.com>, troyf@microware.com (Troy Frericks) writes:
> In article <1992Dec19.192819.1816@adobe.com> pngai@adobe.com (Phil Ngai) writes:
> >If I were a terrorist, I would drool at the thought of being able to
> >get such wonderful bombs so easily... All you'd have to do is arrange
> >for the vacuum valve to be opened on command or the magnetic bearing
> >to be turned off, etc.
> >
> >BOOM!
> 
> Modern composit materials, when used in a flywheel, will disintegrate
> with such a failuar.  This bomb would be about as wonderful as some
> fiber-glass insulation falling out of your attic.

AARRGGGHHH!

Flame on.

The rampant idiocy on flywheels just continues.  How many ways do people have
to be told about conservation of energy?

Don't contribute to the discussion if you don't know anything and haven't
at least read a few articles in it, for cryin' out loud.  I figure there's
been about 1 post every 4 or 5 hours over the past week or so, on average,
refuting this lunacy about "fluff".

Get it through your thick head - energy is conserved.  A flywheel that can power
a car for 600 miles stores basically the same energy that gasoline to power it
the same distance contains.  Do you know anything about fuel-air bombs?  Do you
realize how big an explosion a few gallons of gas can make, when properly mixed
with air?  Do you realize that a hyper speed flywheel fails in microseconds,
releasing all that energy at once?

You think fluff is harmless?  Let's tie you down and hit you with "fluff"
traveling at several km/s and at a temperature of a few thousand degrees.
Let's see if we can find any teeny parts of you after the impact.

Fluff falling out of an attic, indeed.

I'm really tiring of this nonsense, so while I politely corrected the
first posters in their misconceptions - you get flamed, boy.

> >My opinions are my own.

Good thing - they're pretty damned stupid for anyone else.


--
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov
From: dhi00@ccc.amdahl.com (mofo )
Newsgroups: sci.electronics
Subject: re: impedance matching
Date: 21 Dec 92 16:51:38 GMT
Reply-To: dhi00@juts.ccc.amdahl.com (mofo )
Distribution: na
Organization: Amdahl Corporation, Sunnyvale CA

putting a passive component in line with your 4 ohm speaker will match
your amplifier but will absorb half the power output.  you want something
that delivers all the power to the speakers but presents an 8 ohm load
to the amp.  most common way to do this is to put a matching transformer
between the two.  they would either be rated as 4ohm to 8ohm or in terms
of voltage ratio (e.g., 140v:100v).  

but in answer to your original question, yes a 4 ohm resistor would 
protect your amp.

d
From: baden@sys6626.bison.mb.ca (baden de bari)
Newsgroups: sci.electronics
Subject: Re: [* Vision System *]
Date: Mon, 21 Dec 92 19:53:47 CST
Organization: System 6626 BBS, Winnipeg Manitoba Canada

 
        Re: MICRO-EYE
 
                If you have more information on the matter, please 
foreward it to me... 
 
                        Thanks.
        >>Baden<<

Newsgroups: sci.electronics,sci.energy,rec.autos
From: jeh@cmkrnl.com
Newsgroups: sci.electronics
Subject: Re: help - tv remote
Date: 31 Dec 92 09:49:35 GMT
Distribution: sci
Organization: Kernel Mode Consulting, San Diego, CA

In article <1992Dec29.4265.27307@dosgate>, "glen mead" <glen.mead@canrem.com> writes:
> [...] Does anybody have any suggestions which would allow me to
> build some sort of circuit which would allow her to select any one of
> these 3 (and only these 3) stations with the press of a single button?  
> was thinking of one of the older wired remotes which had a series of
> buttons along the top with a seperate button for each channel but I'm not
> sure if they go up to 38.  

Those older remotes were (if you're thinking of the same thing I am) for 
varactor-tuned cable boxes.  The buttons simply select from one of 'n' 
voltage dividers and the varactors in the box act accordingly.  Probably
not a good answer for this problem.

Someone else has already mentioned that you could probably hack up a remote
and "press its buttons" from a sequencer circuit of your own design.  

Another idea is to get one of the universal remotes (such as Memorex CP8;
a version is still sold by Radio Shack, I believe) which can memorize 
sequences of keystrokes which can then be activated by a single button (or
maybe two). 

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh
Newsgroups: sci.electronics
From: jmorriso@ee.ubc.ca (John Paul Morrison)
Subject: Re: components identification
Organization: University of BC, Electrical Engineering
Date: Tue, 29 Dec 1992 22:38:18 GMT

In article <C00KFJ.K2t@dei.unipd.it> red@esse5.dei.unipd.it (Piergiorgio Sartor 274199/IL) writes:
>Does anyone know what are the following components:
>
>MC3487 (this is an IC)

It's a Motorola Quad EIA-422 line driver with tri-state outputs.

>PE-5762 (this has 6 pins, seems a rele')
>
>please reply possibly via e-mail.
>thanks a lot in advance,
>-- 
>					red@paola.dei.unipd.it
>					red@sabrina.dei.unipd.it


-- 
__________________________________________________________________________
 John Paul Morrison                     |  
 University of British Columbia, Canada |  
 Electrical Engineering                 |   .sig file without a cause
 jmorriso@ee.ubc.ca              VE7JPM |  
________________________________________|_________________________________
Xref: sparky sci.electronics:21369 comp.robotics:2709