HDTenEightyP/NetNews huggingface dataset:
From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.electronics
Subject: Re: CMOS Oscillator
Date: 20 Aug 92 23:52:04 GMT
Article-I.D.: u.1992Aug20.235204.25395
Organization: University of Washington, Seattle

In article <1992Aug18.140051.10073@donau.et.tudelft.nl> elmar@dutentb.et.tudelft.nl (Elmar van Ginneken) writes:

>What I am looking for is a low power oscillator (<.5 mA @ 5V) running
>at a frequency of roughly 1 MHz.
>However, the frequency-determining component should be an inductor with
>a value of approx. 75 uH. (YES, I'm trying to measure inductance-change..)

	You can make an RL oscillator with a CMOS Schmitt trigger
gate; the time constant is L/R, so your 75 uH inductor will 
require about a 470 ohm resistor.  That would draw too
much current, so try:


+5---------VVVVV--+---VVVVV---GND
                  |
                  +---VVVVV--+
                  |          |
                  -          +----<Lx>----+
                  -          | |\         |
                  |          +-| >O-------+
                 GND           |/

with the two top resistors circa 10k ohms, and the capacitor
1uF (preferably ceramic).  The current from the inverter (a 74HC14
would be best) will come to about 2 mA AC; it would be prudent
to use several inverters in parallel to generate this much
current.  You get six to a package, so:


     |\     |\     |\
-----| >O---| >O-+-| >O--+
     |/     |/   | |/    |
                 |       |
                 | |\    |
                 +-| >O--+
                 | |/    |
                 |       +------
                 | |\    |
                 +-| >O--+
                 | |/    |
                 |       |
                 | |\    |
                 +-| >O--+
                   |/

will be the full 'expansion' of the inverter.

	The problem here is that the current drain will come to nearly
three mA; without using an oscillator that has a lower threshold
voltage than CMOS Schmitt triggers, the inductors you are using
cannot achieve oscillation at these frequencies with the 0.5 mA
current you require.

	So, you will want to raise the resistance, thus lowering
the frequency (to one kHz or so), and use a PLL to generate
a tracking 1MHz signal; this requires three more IC's, a 74HC4046
for the PLL and two MC14520's for the dividers (or perhaps one
4060 or 4020 or 4040 for the divider).

	John Whitmore
Newsgroups: sci.electronics
From: murphy@symcom.math.uiuc.edu (Michael L. Murphy)
Subject: Tuner for Sanyo VCR (model VHR 9280)?
Summary: channels above 30 do not work clearly
Followup-To: poster
Organization: Math Dept., University of Illinois at Urbana/Champaign
Date: Fri, 14 Aug 1992 16:48:09 GMT
Keywords: VCR, electronic tuner

    I have a Sanyo VCR (model VHR 9280, 125-channel, cable-ready, on-screen
programming, 2-head, HQ) that exhibits the following symptoms.  After about
1/2 hour of being plugged in, channels 31-38 (our CATV here in Champaign/
Urbana doesn't go higher than that) fail to tune in.  They look like the
signal is extremely weak or the signal is not tuned properly (B/W and
wavy, static-filled.)  When tuning in the same channels with the TV,
they look perfect.  Also, they come in the first 15-30 minutes that the
VCR is plugged in (but pressing the POWER switch off and turning it on
does not help at all).

    I suspect the VCR's electronic tuner is at fault.  I also expect that
the problem may be caused by heat-buildup (but I'm not sure about that.)
The VCR also has no way of fine-tuning channels (it apparently uses some
AFT system.)

    What can be done (besides taking it into Sanyo for repairs)?  Can the
electronic tuner be cleaned/repaired/replaced?  I am competent with
handling a soldering pencil, so if a replacement part is available, I
could theoretically do the repairs myself.  But first I need to know
where to begin.  If the tuner can be cleaned somehow, this would be
optimal.  Please address all replies to murphy@symcom.math.uiuc.edu
(if you submit a follow-up article, I may not read it, but other
sci.electronics people may be interested in the contents of your
article, so you may want to post as well as e-mail.  I have a feeling
that the electronic turers are the most vulnerable parts of TV's and VCR's,
and I'd like to know how to fix 'em.)  Thanks for your help.
-- 
+=And=the=Master=said=unto=the=silence,="In=the=path=of=our=happiness=shall=+
\ we find the learning for which we have chosen this lifetime." - R. Bach   /
/ Michael Murphy, programmer (got a job this A.M.!)  Address: 47-164th Pl.  \
+=send=e-mail=to=<murphy@symcom.math.uiuc.edu>==/^\==Calumet=City,=IL=60409=+
Newsgroups: sci.electronics
From: rcain@netcom.com (Robert Cain)
Subject: Re: PD schematic capture, layout and route?
Date: Wed, 12 Aug 92 18:17:16 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 

I've found the real thing.  However, it does have limited capacity.
approx 40 IC's and a 5" by 5" board.  It is schematic capture, layout
and routing!  The best part: it's an actual PADS package from CAD Concepts
who to my knowledge are the king of the field.  The next best part: it
is *free*.  The add calls it shareware but they decided on freeware after
the add.  It is fully functional, just limited capacity.  Obviously it is
intended as a teaser for their $1500 product that has very few limits.  If
it could fill your needs (I'll bet larger designs could be partitioned and
patched using logical "connectors") call 1-800-554-SALES and ask for the
sharware PADS-PCB.  Clever marketing.  It suits my design perfectly and
you can bet that if and when I begin making any money on it I'll go for
the top of their line.

Bob
-- 

Bob Cain    rcain@netcom.com   408-358-2007

The universe is one of those things that happens from time to time.

               PGP public key available on request.
Newsgroups: sci.electronics
From: cgordon@vpnet.chi.il.us (gordon hlavenka)
Subject: Re: A construction question about front panels for home-brew projects...
Organization: Vpnet Public Access
Distribution: na
Date: Sat, 22 Aug 1992 23:02:41 GMT

 bonobo@Ingres.COM (David Victor) writes:
>I'm trying to make a nice-looking aluminum front panel for a project,
>and I'd like to be able to use rectangular switches, possibly other
>squared-off displays, etc.  How do you cut a perfectly-squared-off hole
>in an aluminum panel?  Is there some home-brew method I'm not aware of?

I do this with Greenlee punches.  They're pretty expensive ($10 to
$300, depending on size/shape) but they work great.  You just drill a
hole, fit some parts around it, and tighten a nut.  Bingo -- clean
hole.  (The expensive punches do weird but useful shapes like DB-25
connector patterns)

Round and square punches can be had in the $25 range at well-stocked
hardware (and sometimes auto parts) stores.  A rectangular hole is
done in several passes with a square punch.

>Also, what's a good way to do the lettering?  I've got a LaserJet, but
>how do you transfer what's on paper to what's on the panel?  

I've had good success with "Stickyback" laser film.  This is a matte
finish self-adhesive sheet which works in laser printers /
photocopiers.  I bought it from:

Saga
Division of Dade, Inc.
Interchange Office Park
400 Highway 169 South
Minneapolis, MN  55426-1199

I saw an ad which included a phone number (which I have since lost)
and called them.  They sent several sample sheets so I ordered a box.

>Recently, I heard about a method of PCB manufacture whereby you print
>your PCB design to some special type of paper, iron it on a copper-clad
>board, and then etch as usual.  Seems to me there might be something
>similar for lettering.

An outfit called "Dark Horse Productions" makes a special toner
cartridge which is designed for heat transfer.  Their target market is
T-shirts, but they say it can also be used for panel lettering.  I
have their sample pack at work; I couldn't get it to transfer to
aluminum very well, though.  Email me if you want their address and
I'll look it up at the office.

There's also a special paper which dissolves in water; you can use it
to make real decals with your laser printer!  It's also been discussed
as a possible PCB etch resist.  I don't have the details but I'm sure
someone will enlighten us...

-- 
----------------------------------------------------
Gordon S. Hlavenka           cgordon@vpnet.chi.il.us
  Don't forget:  Dave Barry/Joe Walsh in November!
Newsgroups: sci.electronics
Subject: re: Guided Vehicles
From: kwilli@elaine.ee.und.ac.za (KEVIN WILLIAMS : THIRD)
Date: 13 Aug 92 12:00:12 +0200
Distribution: sci.electronics
Organization: Electronic Eng., Univ. Natal, Durban, South Africa

I am currentry investigating circuitry to control a model car along a fixed 
track by means of a wire taped to the floor which carries some high 
frequency signal.

I would really appreciate hearing from anyone who has tried this before, and 
is willing to discuss some of the problems or successes you've had.

Thanks!

Kevin Williams

Department of Electronic Engineering
University of Natal, Durban
(KWILLI@ELAINE.EE.UND.AC.ZA)
From: dchien@boole.seas.ucla.edu (David H. Chien)
Newsgroups: sci.electronics
Subject: Lithium Type 76 button batt. - any?
Date: 17 Aug 92 17:47:01 GMT
Distribution: usa
Organization: SEASnet, University of California, Los Angeles


    I'm looking for a longer lasting Type 76 battery.  I use Silver Oxides
now and my camera just eats them up like Apple Jacks.  Are there lithium
replacements available?
    Thanks,
    david :)   dchien@boole.seas.ucla.edu

    lithium > alkaline > silver oxide, right? 
Newsgroups: sci.electronics,comp.sys.mac.hardware
From: tcmay@netcom.com (Timothy C. May)
Subject: Re: PowerBook 100 LCD screen replacement, the sad conclusion
Date: Fri, 14 Aug 92 08:42:04 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 


I'd like to thank Fred Martin for his postings on his cracked PB 100
saga. It scared me into being even more careful with mine.

Much as I like my 100 (small size, acceptable speed, nice ergonomics, etc.),
I am worried about Apple's quality control.

My 100 has been back to the repair center in Texas _twice_ for the same
problem (for those who are interested: the charger wasn't charging the
battery, the full-empty indicator was bouncing around, etc. Both times
Apple swapped in a new logic board, all covered by my warranty).

One of the tilt-up feet broke within weeks of purchase...I hear this is 
a common problem (and that Apple has fixed it in new units).

The 100 does not seem to be holding up as well as I'd hoped. Your tale of
the cracked case reinforces this feeling I have.

Sad

-- 
..........................................................................
Timothy C. May         | Crypto Anarchy: encryption, digital money,  
tcmay@netcom.com       | anonymous networks, digital pseudonyms, zero
408-688-5409           | knowledge, reputations, information markets, 
W.A.S.T.E.: Aptos, CA  | black markets, collapse of governments.
Higher Power: 2^756839 | RSA MailSafe Public Key: by arrangement
From: cchapman@matd.gatech.edu (Charles H. Chapman)
Newsgroups: sci.electronics
Subject: Re: Caller ID charges???
Date: 12 Aug 92 18:19:43 GMT
Organization: Georgia Institute of Technology

In article <1992Aug4.162418.1452@mailer.cc.fsu.edu> mayne@eta.cs.fsu.edu (William Mayne) writes:
>
>Has anyone come out with a caller id device which can be programmed
>to check a user supplied list of numbers and give the name, and
>block calls from specified numbers? That might convince me to get
>caller id. The call blocking would be unnecessary since I could always
>program in "Don't answer" for blocked numbers. I pick up some calls
>immediately rather than let my answering machine screen calls as I
>usually do now.
>

I've built a device that does a similar function but since there are
potentially millions of telephone sales people I'd want to block, I block
all calls *except* ones on my aproved list of callers.  All non-aproved
callers and calls from CID blocked numbers get routed to the answering 
machine.

Chuck

Charles H. Chapman  (GTRI/MATD)             (404) 528-7588
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:     ...!{allegra,amd,hplabs,ut-ngp}!gatech!matd!cchapman
Internet: cchapman@matd.gatech.edu
From: rbs@aisb.ed.ac.uk (Robert Scott)
Newsgroups: sci.electronics
Subject: class D amps
Date: 15 Aug 92 21:09:15 GMT
Reply-To: rbs@aisb.ed.ac.uk
Followup-To: sci.electronics
Organization: Department of AI, University of Edinburgh

I've recently been following a tread on rec.audio about class D audio amps.
As I understand it, in a class D amp, the audio signal is converted into
a pulse width modulated clock signal of around 100 kHz.
This is then fed into the loudspeakers which by their nature convert
the pulses back into audio.

That's about the sum total of my knowledge.
Would anyone like to post or send me a more explicit description of
how one of these amps works.
I'd like to know:

1) exactly how the thing amplifies the signal;
2) whether one needs special speakers or speaker parameters for this system;
3) how to build a simple low power example of such an amplifier for my
   own amusement to prove the priciple to myself.

Following on from this, I had the idea that an integrated digital CD
stage class D amp could be constructed where no analgue stage would be
needed. The circuitry would convert from the PCM data from the disk
to PWM signals for the loudspeakers.

Is anything like this remotely possible 
or am I BSing with the best of them?

-- 
Rob Scott
Department of AI                Tel: 031-650-2713
University of Edinburgh         FAX: 031-226-2730
80 South Bridge               email: rbs@aisb.ed.ac.uk
EDINBURGH
EH1 1HN
Newsgroups: sci.electronics
From: gerry@bluemoon.rn.com (Gerard M. Foley)
Subject: Re: AEA-FAX
Organization: Blue Moon BBS ((614) 868-998[024])
Date: Mon, 17 Aug 92 09:59:12 EDT

then@vipunen.hut.fi (Tomi  H Engdahl) writes:

> In article <6LRgPB4w165w@bluemoon.rn.com> gerry@bluemoon.rn.com (Gerard M. Fo
> 
> >   Since it seemed busted anyway, I just now pried it open.
> >I have not finished tracing the schematic diagram of it,
> >but believe it or not, it containes the following parts,
> >and no more:  1 Dual Op-Amp  5 resistors  4 diodes 4
> >capacitors! (Sorry for the spelling of "contains" up
> >there).  There's magic in electronics!
> 
> The magic is mainly in software, because most decoding of the
> fax signal is done in software. That's what I think.  I have seen 
> a shareware program called Hamcomm, which can send and decode 
> morse, rtty etc. signals. The circuit needed for decoding contains one
> Op-amp and some passive components. The circuit filters the incoming
> signal and converts it to square wave, which is send to one of the input pins
> in the serial port. Every time the state in that input changes, UART
> generates an interrupt. The software measeres time between interrupts
> and so determines the signal frequency. When the program is used for sending,
> the PC speaker ouput is connected (via passive low-pass filter) toi the
> transmitter. Quite a hack.
> I think that the fax device you mentioned works in the quite same way.
> 
>  
> --
> 
> Tomi.Engdahl@hut.fi            "Don't force it; get a larger hammer"
> then@vipunen.hut.fi                        

   The op-amp was a Motorola LM358N.  I replaced it with a
Radio Shack Cat.No.276-038, price $0.99, and the AEA-FAX
seems to work again.
    It looks to me as if the AEA-FAX gets its power from
RS232C line 20 (DTR) when that is made positive.  It seems
that the device is reset and interrogated on line 4 (RTS)
and that the brightness level is proportional to the time
that elapses until line 6 (DSR) changes state.  If any
software geniuses have good ideas on how to program to
make this work, I would be very happy to hear from them.
     For VGA display, the device and software must perform
the conversion to a gray level 480 times for each FAX
drum revolution.  The FAX drums turn at 1, 2 or 4 times
per second.

 This is from
     gerry@bluemoon.rn.com
who doesn't have his (or her) own obnoxious signature yet
From: rkarlqu@hpscit.sc.hp.com (Rick Karlquist)
Newsgroups: sci.electronics
Subject: Re: Impedance Analysis on transformers
Date: 12 Aug 92 16:42:18 GMT
Organization: Hewlett-Packard, Santa Clara, CA

In sci.electronics, amir@smsc.sony.com () writes:

> It seems that LCR analyzers can not detect capacitance in parallel with
> an inductor.  So, I have been looking at the (very expensive) HP 4194A
> impedance and gain/phase analyzer.  This box gives you an equivelant circuit
> (up to 5 devices).  Is this an overkill?  Are there cheaper solutions that
> are just as good?

> -- 
> Amir H. Majidimehr
> Operating Systems Group
> Sony Microsystems
> amir@sony.com  | ...!{uunet,mips}!sonyusa!amir

I have used the HP 4194 extensively for transformer characterization and
would say it really is what you need if you want to do any serious modeling.
Before we had it, we used a vector impedance meter.  Theoretically, it
makes the same measurements.  But the ability of the 4194 to give you
a display of various parameters vs. frequency gives you much more 
insight into what the component is doing.  You can display Z, phase, or
inductance (either series or parallel) and loss resistance.  I really
can recommend this box highly (and I'm not just saying that because it
is made by my company).  My designs have been improved considerably due
to the use of it.  It gives you an unfair advantage over other engineers
who are designing without it.

Rick Karlquist
Hewlett-Packard Santa Clara Division
rkarlqu@scd.hp.com
From: marcusj@apricot.co.uk (Marcus Jenkins)
Newsgroups: sci.electronics
Subject: Re: OTP 80C51s?
Date: 19 Aug 92 07:51:51 GMT
Organization: Apricot Computers Limited

mkl@nisc.sri.com (Mark Lottor) writes:

>Maybe I'm confused here.  I want to use 80C51's in a new project, but
>I need all the I/O lines.  The 87C51 EPROM part is very expensive for
>small productions runs.  Doesn't someone make an OTP version of the
>80C51 that is cheap, like $10-15?  If so, who, and where can I get them?


Dare I say, Intel?  The 87C51 is an comes in OTP form from Intel,
Signetics and AMD, just to name a few.  And, yes, you are looking
at $10-$15 in a reasonable quantity.  If you're sure of your code,
I think masking becomes cheaper at about 5000 parts.

As an aside to this, does anybody know of a manufaucturer *apart from
Signetics* who does an EPROM CLCC 87C51?  It's just that the part I've
just ordered from them is about $150 *each*!  Secondly, does anybody know
whether any manufacturer second-sources Intel's 87C51FX range?

As a second aside, Intel *were* going to make a Flash 87C51.  One of 
those would be marvellous.  I was distraught to see that they changed
their minds and removed the 87C51FC from the 1992 docs..

Sorry, I'm not au fait with the US distributor setup, but I'm sure
if you rang Intel, they would give you a 'phone number where you can
get the OTP parts off the shelf.


 _ _ _
' ) ) )                         Internet: marcusj@apricot.co.uk
 / / / __.  __  _. . . _        UUCP: marcusj@apricot.uucp
/ ' (_(_/|_/ (_(__(_/_/_)_      If all else fails from US, try:  
Marcus Jenkins                  apricot!marcusj@relay.EU.net
Tel: +44 21 472 3002  Fax: +44 21 471 2935
Disclaimer:  Anything I wrote above is, of course, my own view and
             does not in any way represent my employer.
Newsgroups: sci.electronics
From: gerry@bluemoon.rn.com (Gerard M. Foley)
Subject: Re: AEA-FAX
Organization: Blue Moon BBS ((614) 868-998[024])
Date: Tue, 18 Aug 92 10:09:32 EDT

gerry@bluemoon.rn.com (Gerard M. Foley) writes:

> then@vipunen.hut.fi (Tomi  H Engdahl) writes:
> 
> > In article <6LRgPB4w165w@bluemoon.rn.com> gerry@bluemoon.rn.com (Gerard M. 
> > 
> > >   Since it seemed busted anyway, I just now pried it open.
> > >I have not finished tracing the schematic diagram of it,
> > >but believe it or not, it containes the following parts,
> > >and no more:  1 Dual Op-Amp  5 resistors  4 diodes 4
> > >capacitors! (Sorry for the spelling of "contains" up
> > >there).  There's magic in electronics!
> > 
> > The magic is mainly in software, because most decoding of the
> > fax signal is done in software. That's what I think.  I have seen 
> > a shareware program called Hamcomm, which can send and decode 
> > morse, rtty etc. signals. The circuit needed for decoding contains one
> > Op-amp and some passive components. The circuit filters the incoming
> > signal and converts it to square wave, which is send to one of the input pi
> > in the serial port. Every time the state in that input changes, UART
> > generates an interrupt. The software measeres time between interrupts
> > and so determines the signal frequency. When the program is used for sendin
> > the PC speaker ouput is connected (via passive low-pass filter) toi the
> > transmitter. Quite a hack.
> > I think that the fax device you mentioned works in the quite same way.
> > 
> >  
> > --
> > 
> > Tomi.Engdahl@hut.fi            "Don't force it; get a larger hammer"
> > then@vipunen.hut.fi                        
> 
>    The op-amp was a Motorola LM358N.  I replaced it with a
> Radio Shack Cat.No.276-038, price $0.99, and the AEA-FAX
> seems to work again.
>     It looks to me as if the AEA-FAX gets its power from
> RS232C line 20 (DTR) when that is made positive.  It seems
> that the device is reset and interrogated on line 4 (RTS)
> and that the brightness level is proportional to the time
> that elapses until line 6 (DSR) changes state.  If any
> software geniuses have good ideas on how to program to
> make this work, I would be very happy to hear from them.
>      For VGA display, the device and software must perform
> the conversion to a gray level 480 times for each FAX
> drum revolution.  The FAX drums turn at 1, 2 or 4 times
> per second.
> 
>  This is from
>      gerry@bluemoon.rn.com
> who doesn't have his (or her) own obnoxious signature yet

  Second thoughts make me question my timing hypothesis.
It seems clear, however that line 4 controls and line 6
receives the info.

 This is from
     gerry@bluemoon.rn.com
who doesn't have his (or her) own obnoxious signature yet
Newsgroups: sci.electronics
From: jeremiahw@wl.aecl.ca
Subject: RE: Phone in use light - help!?
Organization: AECL RESEARCH
Date: Mon, 17 Aug 1992 15:43:48 GMT

Seems that not many know the phone electrical specs?  The phone is a 600 ohm
resistor that is placed across the line when it goes off hook.  The line runs
48 volts (plus or neg depending on orientation) when everything is on hook.
This is a DC voltage and it drops when hones are put off hook.  The ringing
voltage is 96 volts AC at 20 Hertz.  This adds to the DC measurement to make
a peak value of almost 150 volts while its ringing.  There is a current limit
on what the line can provide.  I'm not sure what it is but you know how all
these machines you can connect have a value on the bottom and the sum shouldn't
exceed 100 (at least where I live)  This is the current total that can be
provided by the line.  The phone company says it is illegal to stick non FCC
approved devices on the line (and for good reason) but if you isolate your
devices electrically they don't mind.  I'm sure that if they found out people
were recharging batteries and running motors off it they would have a fit.
I'm not telling you not to do it.  Just don't tell me you are and don't get
caught.

>>Jerry   (jeremi@bode.ee.ualberta.ca)
Newsgroups: sci.electronics
From: aviz@lanai.cs.ucla.edu (Dr Algirdas Avizienis)
Subject: Needed: Decibel meter...
Organization: UCLA Computer Science Department
Distribution: usa
Date: Sat, 22 Aug 92 20:08:52 GMT

	Hello.  I am in need of a device that can measure volume in
decibels.  Can someone refer me to a store/mail-order house that might
carry such an item?  How much should I expect to pay.

Thanks.

Please reply by e-mail, as i doubt this is of general interest.

Newsgroups: sci.electronics