HDTenEightyP/NetNews huggingface dataset:
ReplyTo: tchannon@black.demon.co.uk
Subject: Re: Spectrum anaylsers
Distribution: world
X-Mailer: cppnews $Revision: 1.18 $
Organization: null
Date: Tue, 6 Oct 1992 22:44:22 +0000

> Spectrum analyzers work the same way that virtually all radio receivers do.
> The input signal is "heterodyned".  What this means is that the input 
> signal is sent into one port of a mixer (RF).  Another signal, slightly offset
> 
> deleted ..

I agree, especially about reading up on it.

For crude experimentation try building something using a voltage tuned TV 
tunerhead. Add a narrowband IF amp and a fast envelope detector.

Sweep the tune voltage in sync with the 'scope X sweep, viola!

Question from me anybody: I have seen reference to the use of dispersal 
filters as a means to make simple spectrum analysers. What are the 
characteristics of these filters?

  TC. 
    E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk
From: bills@inqmind.bison.mb.ca (Bill Shymanski)
Newsgroups: sci.electronics
Subject: Flourescents on DC
Date: Sat, 10 Oct 92 22:31:23 CDT
Organization: The Inquiring Mind BBS  1 204 488-1607

I've seen DC operation of flourescent lamps described in at least
one Westinghouse catalog; the life time is shorter due to end-darkening
of the lamps, but it can be done directly on a suitably high DC voltage.
Once the arc is started, its terminal voltage for a small lamp is only
on the order of 100 volts; if the DC supply is at least this high, the
kilovolt pulse to start the arc can be supplied by other means.
  Where I work, we have a number of mercury vapour lamps running
directly on 250 volts DC - these are pretty well standard 400 watt
lamps, with a resistor ballast to limit current.  The ballasts get
quite hot, of course, and overall lighting efficiency is low, but
the mercury vapour lamps last much longer in overhead crane service
than the former lighting system.  A 250 volt 1000 watt incandescent
lamp has a long skinny filament that doesn't like being shaken -
a real problem on a scrap charging crane in a steel mill. 
  Bill

bills@inqmind.bison.mb.ca
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607
Newsgroups: sci.electronics
From: nagle@netcom.com (John Nagle)
Subject: Re: what's a SAW?
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Distribution: usa
Date: Mon, 12 Oct 1992 17:21:19 GMT

hbg6@phx.mcd.mot.com (John Schuch) writes:
>Could someone explain what a SAW filter is and what it is used
>for? ( the $.25 explanation will do )

        Surface Acoustic Wave filters are analog computational elements
usually used to perform correlations.  They're typically used with
"chirp" radars, where the outgoing signal is a random or psuedorandom
bitstream, and the return signal needs to be correlated with the outgoing
signal to obtain the range.  SAW devices do this by electromechanical
means, driving a suitably shaped flat plate with multiple (typically 2)
piezoelectric transducers, and detecting, along one edge, where the 
waves reinforce.  Remember ripple tanks from high-school physics?  Same idea.
See any textbook on modern radar techniques for details.

        This is mostly a military technique, but if you need to operate
many radars or lidars in a small space (consider automobile anticollision
systems for freeway driving) it's the best known way to do it.

					John Nagle
Newsgroups: sci.electronics
From: wlsmith@valve.heart.rri.uwo.ca (Wayne Smith)
Subject: Re: TV->RGB hookup?
Organization: The John P. Robarts Research Institute, London, Ontario
Date: Thu, 8 Oct 1992 13:42:59 GMT

In article <1992Oct08.042314.18221@ssc.com> markz@ssc.com (Mark Zenier) writes:
>an938@cleveland.Freenet.Edu (George II Lenzer) writes:
>
>"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.

I bought the kit, and I agree that is high quality.

The problem is is that I can't get it to work with my old CGA monitor.
(Hitatchi - Amdek clone).
I traced the input RGB signals and bypassed the internal ttl buffer
chip.  When I apply 0 to 1 or 2 volts on either red, or green, or blue,
the screen color gets modulated accordingly.

But when I hook up the converter (and use composite out from my vcr),
the picture is always black & white.  The vertical sync locks very
very weakly, and the horizontal sync doesn't lock at all.

I think the monitor doesn't like the equalization pulses in the
vertical interval.  
Does anyone know how ntsc sync differs from the old CGA system?
I tried the thing on a Sony NTSC monitor, and it works great.
I don't know why I don't get color on the CGA monitor.

Any ideas?
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: How do LCD TV screens work?
Date: 12 Oct 92 18:45:20 GMT
Organization: Hewlett-Packard, Fort Collins, CO, USA

> I have a recent SONY model, and it uses a miniature fluorescent light. I had 
> a problem with my first one though. After the unit had been on and warmed up 
> for a while, a couple of the pixels would remain continuously in the 
> transmissive mode (this was an active matrix set). I have heard that the 
> defect free yield rates on these displays is one of the factors that is 
> keeping prices high. Any comments on this?
> 

That's certainly one of the factors keeping LCD prices up there; you can
basically think of an LCD, particularly an "active matrix" type, as simply
a big IC, made using similar processes to conventional IC fab.  From this
model, I think you can understand the role defect density plays in
determining yield, particularly for large panels or those with fine detail
(i.e., high resolution).  An additional problem is the need to maintain
uniform spacing between the front and back electrodes (which are metallization
on glass) to within a very small tolerance; this becomes particularly
troublesome for large panels (where the glass will "sag"), and that's limiting
the practical size of LCDs at present.

LCD manufacturing processes at present are pretty much "batch mode," and the
inefficiencies here are another thing that's keeping costs up.  Look for some
drastic changes in LCD processes over the next decade.


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: myers@hpfcso.FC.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: A Question about RAM sizes.
Date: 14 Oct 92 20:21:59 GMT
Article-I.D.: hpfcso.7480130
Organization: Hewlett-Packard, Fort Collins, CO, USA

> 	I am not sure if I understand the way RAM's are catagorized in my
> electronics catalogs.  When a RAM chip is defined as 16K x 1, does that
> mean that it has 1 bit data bus?  If so, then a 2K x 8 chip would
> hold the same amount of data (bits) as a 16K x 1 chip, but would only be 
> able to address one *BYTE* at a time, while the 16K x 1 chip would be able 
> to address 1 *BIT* at a time.  Let me know if I am thinking of RAM    
> sizes the correct way.
> -- 

Yes. Exactly right.


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: mgm@world.std.com (michael g moncur)
Subject: Re: Triggering multiple flashes to "paint with light"
Organization: The World Public Access UNIX, Brookline, MA
Distribution: usa
Date: Fri, 9 Oct 1992 06:46:33 GMT

fontana@dogwood.cis.ohio-state.edu (Mark Fontana) writes:
 


>A friend and I have some ideas for photographs using the "painting with
>light" technique.  In short, this involves taking a completely dark
>room full of interesting objects, opening the shutter, and popping a
>flash multiple times from various angles.  The hard part here is not to
>catch your own image or shadow in the picture.

>Well, I have an idea.  A friend of mine works in a photo lab and grabbed
>the guts of a dozen of those throwaway cameras with built-in flash.
>So I now have 12 identical little flash circuits, each running on its
>own AA battery.

>What I'd like to do is position these tiny flashes all around the room,
>then fire the first flash manually.  The other flash circuits would detect
>this main flash and delay for a preset interval before firing.  That is,
>the first flash would fire 1 sec after the main flash, the second would
>fire 2 seconds after the main flash, etc.

           <some stuff deleted.>
>Thanks,

>Mark Fontana

  Well, if I were going to do that, I wouldn't mess with light-detection. 
That would be incredibly difficult, especially building n amount of
circuits.  Instead, I'd make a "sequencer" circuit - probably a
combination of a 555 timer, a BCD counter, and a BCD-to-1-of-16 decoder. 
This would result in the outputs turning on, one at a time, at a preset
interval (depending on the r's and c's on the 555.) 
 
 I would then run tiny wires all over the room from the sequencer circuit
to each of the flashes.  You'd probably need driver transistors and
perhaps relays in order for a digital output to control the flashes.
 
 Sounds like an interesting photo technique.  I'd like to hear about it if
it works...  
 
 If you need chip numbers for the circuit I described above, I can dig
them up.  let me know.  
 
 If you really want a separate light-detector for each flash, it would be
a matter of photo transistors and driver circuitry hooked up to a 555
timer wired as a one-shot timer, wired in turn to the same driver
transistor / relay mentioned above and then hooked to the flash.
 
 Further questions - best to use Email, since I browse this group rather
quickly, and might miss a reply.
 
--------------------- 
Michael Moncur      mgm@world.std.com (preferred)
                    sysop@onlybbs.via.mind.org
---------------------

-- 
--------------------- 
Michael Moncur      mgm@world.std.com (preferred)
                    sysop@onlybbs.via.mind.org
---------------------
From: jime@countach.telcom.tek.com (Jime Edwards)
Newsgroups: sci.electronics
Subject: RS422 transceivers
Date: 12 Oct 92 22:59:30 GMT
Article-I.D.: tekgen.1399
Reply-To: jime@countach.telcom.tek.com (Jime Edwards)
Organization: Tektronix, Inc., Beaverton,  OR.

Can somebody direct me to a company that makes an
IC that functions as a RS422 transceiver?  Thanks.

Jim Edwards
jime@nesa.telcom.tek.com
Newsgroups: sci.electronics,misc.forsale
From: 6o25@sdf.lonestar.org (Stephen M. Jones)
Subject: VCR signal sender
Keywords: serial cable
Organization: Super Dimension Fortress - Public Acess Unix - Dallas, Tx.. 
Distribution: usa
Date: Mon, 12 Oct 1992 13:06:05 GMT


I have a VCR signal sending device forsale... it lets you have a wireless
set up between your TV and VCR

Videocaster  MTV-1500

make an offer

-- 
Stephen M. Jones (214)436-4622 
SysAdmin <-> Super Dimension Fortress PAU 
6o25@sdf.lonestar.org
Newsgroups: sci.electronics
From: arya@cs.sfu.ca (Arya Raychaudhuri)
Subject: job info for microelectronics
Organization: CSS, Simon Fraser University, Burnaby, B.C., Canada
Date: Wed, 7 Oct 1992 23:30:52 GMT


looking for a list of names and addresses of employers willing to recruit experienced 
professionals in the area of microelectronic semiconductor device characterization, 
modeling, and reliability analysis. 
Newsgroups: sci.electronics
From: iqbal@pawnee.eel.ufl.edu (M.Iqbal)
Subject: Re: Need help choosing an MCU
Organization: University of Florida
Date: Sun, 11 Oct 92 16:45:46 GMT

MicroController published an artical in October 92 issue discussing
what one look in picking a MCU. I pretty sure that the artical will
help you decide the most appropriate MCU.

Good luck

iqbal

-- 

------------------------------------------------------------------
                                            
      						 >><<<     >>><<<<
Iqbal@sioux.eel.ufl.edu		 		 (o o)     (o) (o)
University of Florida				 [ | ]        | 
                                  		   -         ---

Newsgroups: sci.electronics
From: dionf@ERE.UMontreal.CA (Dion Francois)
Subject: DAC08EP pinout?
Organization: Universite de Montreal
Date: Tue, 13 Oct 1992 22:43:47 GMT

Anybody has the pinout for the (probably National Semiconductor) DAC08EP?
It's a high speed DA converter 8 bits. It could be the same thing (except
for speed) as a DAC801 or DAC803.

Ciao,
--
Francois Dion
    '  _   _   _
 CISM (_) (_)  _) FM       Montreal , Canada       Email: CISM@ERE.UMontreal.CA
      (_)  / . _)             10000 Watts          Telephone no: (514) 343-7511
_______________________________________________________________________________
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Newsgroups: sci.electronics
Subject: Re: Car antenna design help wanted
Date: 9 Oct 92 20:04:41 GMT
Article-I.D.: athena.1992Oct9.200441.4070
Organization: AI Programs, University of Georgia, Athens

I presume you mean an FM antenna.  The usual FM car antenna is a 1/4-wave
whip about 30 inches long, using the body of the car as a ground plane.
This works quite well and is hard to improve upon.  If you wanted a better
one, you'd have to make it longer, which might be awkward.  3/4 wave will
work well, but you can't drive around with 90 inches of wire standing
straight up.

Look at designs for ham radio antennas and adapt them to 90 MHz.  (On the
ground that the weaker FM stations are at the low end of the band.)

AM car antennas are a different story... basically, they're all *terrible*
because they have to be so tiny compared to the wavelength.

-- 
:- 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
Newsgroups: sci.electronics
From: george@beta.ee.ufl.edu (George L)
Subject: Re: Spectrum anaylsers
Date: Wed, 7 Oct 92 08:13:51 GMT

In article <1992Oct4.133239.7918@latcs1.lat.oz.au> dpm@latcs2.lat.oz.au (Odysseus) writes:
>
>they can't use this kind of thing. Performing fft's in real time is not
>really the problem - I know of several frequency domain processors. Is an
>analogue Fourier transform possible?

Well, depending on your resolution needs, a bank of LC resonators would 
probably qualify. It would certainly be nice to have a single analogue part 
that accepted your input on one pin, and provided continuous frequency 
discriminated outputs on another set of (_many_) output pins. At higher 
frequencies, optics are used to perform this function. How about some 
discussion on this. Is there something I have overlooked (it is late) that 
is presently available? Even if only for low frequencies (e.g. audio, VLF)?

>-------------------------------------------------------------------------------
>dpm@latcs1.lat.oz        |  It's time to make love, douse the glim,
>Odysseus                 |  The fireflies twinkle and dim.
>aka The Man With No Face |  The stars lean together
>aka Jabberwocky          |  Like birds of a feather,
>aka Orange               |  And the loin lays down with the limb.
>-------------------------------------------------------------------------------

george@alpha.ee.ufl.edu
Newsgroups: sci.electronics
From: rkornilo@nyx.cs.du.edu (Ryan Korniloff)
Subject: Questions about CB radio
Organization: Nyx, Public Access Unix @ U. of Denver Math/CS dept.
Distribution: usa
Date: Mon, 12 Oct 92 04:29:33 GMT



I'm trying to communicate with a friend about 1 1/2 to 2 miles across
town. I'M suceeding at this but at time's (especially during the day) the
reception is very faint. We're both transmitting at 4 watts. He has a hand
held hooked to a regulated power supply and I'm using a conventional CB
hooked to an unregulated power supply and an antenna mounted on the gutter
attached to the edge of the roof above my window. The antenna is not
grounded. Someone just happend to drive from his location to mine. They
had a 3 watt CB and both my frind and I could hear him loud and clear. I
asked this person how my friend an I could hear him so clearly. He said
his CB is modulated. 
First, would grounding my antenna help reception, and what does
a modulated CB mean? I
Please respond by mail, I don't read this group on a regular basis and by
the time I'M able to connect here, I might forget.
thank you


        -- Ryan Korniloff
        -- rkornilo@nyx.cs.du.edu
From: wb8foz@skybridge.SCL.CWRU.Edu (David Lesher)
Newsgroups: sci.electronics
Subject: Re: Grounded soldering iron tip
Date: 14 Oct 1992 02:17:00 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

You really don't want the tip 'grounded' to power-grid ground.
Instead, you want it at same potential as the circuit you are
working on. They may be completely different.....

--
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: kolstad@cae.wisc.edu (Joel Kolstad)
Subject: Re: Smith Chart
Organization: College of Engineering, Univ. of Wisconsin--Madison
Distribution: usa
Date: 12 Oct 92 11:26:07 CDT

I have a question about this Smith Chart copyright discussion...

How is it that you can copyright what is basically the mere plot of a
mathemetical function!? (z=(1+k)/(1-k))

I mean... if I really didn't have better things to do with my time, I could
have my HP-48 plot a Smith chart, right?  Would that be copyright infringement?

I realize that if you have _the_ Smith chart produced by ??? Electric, you
can't copy it -- just like a book.  But if you regenerate the plot from the
mathematical model?  This seems odd to me...  if so, pretty soon people
will want to copyright things like the Mandelbrot set, etc.!

Very strange...

						---Joel Kolstad
From: eric@zen.maths.uts.edu.au (Eric Lindsay)
Newsgroups: sci.electronics
Subject: Re: C Cross Complier for 68HC11
Date: 13 Oct 92 22:28:47 GMT
Organization: University of Technology, Sydney
NNTP-Posting-Host: zen.maths.uts.edu.au

In <Bw0vr2.6qw@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:

>My understanding is that there's not much hope for this, because GCC has
>some definite prejudices about the type of machine that it's compiling
>for, and "at least 32 bits" is one of them.

I quote from an advert on page 7 of Circuit Cellar Ink's The Computer 
Applications Journal #29 Oct/Nov 1992:
"comes with ... GNU C cross compiler ...under PC-DOS ... C++ and Objective C 
support"  This is for GCB11 68HC11 controller from Coactive Aesthetics, Inc, 
San Francisco.  (I haven't tried it, and don't know the company).

>MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
>              -Hal W. Hardenbergh (1985)|  henry@zoo.toronto.edu  utzoo!henry
Hal has continued to come up with some good quotable things to say about 
the way computers are trending.  I should find a few from recent letters and 
quote them.
--
eric@zen.maths.uts.edu.au  Eric Lindsay, Sch of Maths, Uni of Tech
Don't take life too seriously.
It is only temporary.
Newsgroups: sci.electronics
From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Subject: Re: Need Help with Op-Amps
News-Software: VAX/VMS VNEWS 1.41    
Reply-To: frank@rover.uchicago.edu
Organization: Joint Center for Radiation Therapy
Date: Wed, 7 Oct 1992 23:21:00 GMT

In article <Oct.7.13.47.20.1992.4075@clam.rutgers.edu>, steuer@clam.rutgers.edu (robert Steuer) writes...
>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?

	Try Afb = Rf/R1 + 1 when R1 is very large, (ie almost infinite)

	Now a trick question for a follow up:

	Its easy to do an  inverting amp with gain of 1/2, but how do
	you make a non-inverter have a gain of 1/2?


   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   | |_) _   
                                   | \|_)  Water, taken in moderation, cannot
    "Birthplace of Softball"          |_)  hurt anyone. - Mark Twain
Newsgroups: sci.electronics,rec.music.makers,rec.music.synth
From: jna@silver.lcs.mit.edu (fruit juice everywhere, not one drop to fill me)
Subject: LFO's , Bandpass design / 24db filters
Organization: We Take What We Want, Inc.
Date: Fri, 9 Oct 1992 18:44:05 GMT

If you have ever seen a Jupiter - 6 keyboard, there is a section of the
keyboard marked FILTER.

You have three controls over the filter, Resonance, Cutoff Frequency,
and another one , which I thin is called depth..


I'm looking to BUILD this section of a keyboard.. I own a Korg Wavestation
and I'm in desperate need of making analog filter-like noises... the
wavestation has no resonance control, and won't let you move the filter
cutoff in real time without turning off the sound. I'd like to create a 
complex sound (i.e. sine wave or what have you) off of the wavestation (this is
simple.. just programming) and then pass it into my fliter box and 
move the knobs on the filter box in real-time, changing the sound..

basically the back end of an analog synth, being run by a digital 
synth.

I don't have hundreds of dollars to go and by a classic analog synth, and
would like to build this for about $50...

I assume the filter network is some sort of R/C network... I think it's
a 24dB filter. or so some old literature I have says...

People who own analog synths, tell me what controls you have, I'd like to be
able to build them..

my main goal is to create TB-303 ish basslines...
thanks..

please send mail..
From: garyf@wang.com (Gary Field)
Newsgroups: sci.electronics
Subject: Re: 25 ohm coax cable
Keywords: coax cable
Date: 7 Oct 92 13:05:36 GMT
Organization: Wang Labs, Lowell MA, USA

dhina@dxcern.cern.ch (Mourad Dhina) writes:

>Hello,
>i am trying to realize a circuit i found in an electronics magazine.
>one of the components it uses is a semi-rigid coax cable of
>25 ohms impedance. this is the first time i hear of this (i only
>knew 50, 75 and 93 ohms cables, which are standard). anybody
>knows where to find this?
>Mourad

Put two pieces of 50 Ohm cable in parallel. It should be exactly the same.
Gary

-- 

/*-------------------------------------------------------------------------
   Gary A. Field - WA1GRC, Wang Labs M/S 019-72B, 1 Industrial Ave      
   Lowell, MA 01851-5161,  (508) 967-2514, email: garyf@wiis.wang.com
-----------  Anything not worth doing, is not worth doing well. -----------*/
Newsgroups: sci.electronics