HDTenEightyP/NetNews huggingface dataset:
From: dfs@doe.carleton.ca (David F. Skoll)
Subject: Re: Ohm's law for AC?
Organization: Dept. of Electronics, Carleton University
Date: Mon, 13 Apr 1992 15:20:14 GMT

In <oduNdSC00UhB81Orc1@andrew.cmu.edu> "Raymond C. Chick"
<rc4n+@andrew.cmu.edu> writes:

>I record classical music and have recently begun to investigate the
>affects of cable resistance on mic. level audio signals.  I used two
>cables, one about 20' and the other about 350'.  I passed identical
>signals through each cable and measured the  outputs levels for various
>frequencies.  I found no difference in output level between the two
>cables for frequencies from 100Hz. to 16Khz. Yet, the restistance of the
>short cable was .5 ohms and the long cable was 5.5 ohms.

>Shouldn't the long cable attenuate the signal or even roll of the high
>frequencies?

What was the load on the measuring end of the cable?  If I apply
voltage to a pair of wires with a resistance of 0.001 ohms, and
another with a resistance of 10 000 ohms, and stick a 10 meg-ohm load
on the end, the voltage reading will be pretty much the same in either
case.

>How can I determin the maximum cable length before signal degradation begins?

You need to know the input impedance of your amplifier, as well as the
output impedance of the microphone.  You'd also have to measure the
inductive and capacitive effects of the wire.

--
David F. Skoll
Newsgroups: sci.electronics
From: trond@calvin.phys.ucalgary.ca (Trond Trondsen)
Subject: Data acquisition board (external bus) ?
Date: Mon, 06 Apr 1992 16:11:46 GMT
Organization: Institute for Space Research

Does anybody know where I can get a hold of a data acquisition board/
digital I/O board (I need to read some temperatures, flip some relays,
set some bits) which can be controlled by a PC.  Because the line between
the PC and the board would be very long, I would like to get a board that
communicates with the PC via a UART to the PC serial port.  I.e. not
a board that plugs into the PC bus.  All the catalogues I have are
filled with boards that plug into the PC bus... *not* what I need.
Any pointers?

Thanks!

Trond
LA1OEA/VE6NOR

Newsgroups: sci.electronics
From: dcb@kopachuk.uucp (David Breneman)
Subject: Re: Question about bypassing TV r.f. circuits
Keywords: baseband video, tv rf - if
Organization: Tacoma Screw Products, Inc.
Distribution: na
Date: Tue, 7 Apr 1992 19:59:27 GMT

In article <1992Apr6.145256.9452@eskimo.celestial.com> mann@eskimo.celestial.com (Tom Mann) writes:
>
>Has anyone had any experience modifying tv sets so that the video
>from a vcr is introduced into the video circuits directly rather
>than going through the rf & if circuits. Intuition tells me that
>the picture would be much better if I got away from all of the
>distortion
>introduced by those circuits.

Of course most sets sold today for more then about $300 have video and
audio in jacks, anyway, so this may be a dubious undertaking, but...
When I was in high school I bought an old Sony CV-series skip-field
VTR (1/2" reel-to-reel).  I needed a monitor, of course so I jeeped an
Admiral 19" TV my parents had.  I looked on the schematic for the video
test point where, if you were a service shop, you'd hook up a 'scope
to see if the tuner was working, cut the lead at that point and inserted
a SPDT switch - one way was "tuner" the other was "monitor".  It
worked.  Now on modern sets (this was an "instant-on" preheated tube
model) with all the integrated circuits, the video signal may not
appear at a wire where you can make your modification.  As I said,
nowdays TV/monitors are available at any department store.  In 1974
they were expensive pieces of industrial gear.
Also, if impedance, voltage, etc aren't the same from your VCR's video
output as they are inside the set at the point where you make the
connection, the picture quality may actually be worse.  Good luck.


-- 
David Breneman     Sys Admin, Tacoma Screw Products, Inc. |  ____  ____  ____
dcb@tacoma.uucp              | SCREWIE the TSP CLOWN sez- |   /   /___  /___/ 
 ..!uunet!stephsf!tacoma!dcb |"Stainless steel bolts are  |  /   ____/ / 
CompuServe: 75760,1232       | ferrous but non-magnetic!" |
Newsgroups: sci.electronics
From: jon_sree@world.std.com (Jon Sreekanth)
Subject: How to estimate 9V Alkaline Battery life ?
Organization: The World
Distribution: sci
Date: Mon, 6 Apr 1992 14:48:21 GMT


I'm using a 9V alkaline (Duracell, or some similar store brand) battery
in a circuit which has a fairly low current drain. I estimate 100uA 
constant drain, and about 0.5 mA for maybe 6 hours per day. Also,
the circuit will be functional down to about 4V from the battery. 

Is there some magic formula for estimating, from your experience, or 
any  published specs (where do I find them ?) battery life ? Battery 
life is defined in this case as # of days between buying an average-aged
battery from a drugstore to voltage dropping below 4V ? 

(Right now, I have a 500maH estimate from Panasonic, and I've looked at
Horowitz and Hill. I'm hoping I can get more maH because of the low
drain, and because the circuit can go down to about 4V at least.)

Thanks for any pointers, 

/ Jon Sreekanth

Assabet Valley Microsystems, Inc.           |  Fax and PC products
5 Walden St #3, Cambridge, MA 02140         |  (617) 876-8019
jon_sree@world.std.com                      |
From: lowry@src.honeywell.com (Dave Lowry)
Newsgroups: sci.electronics
Subject: Smart Home Help
Date: 8 Apr 92 16:06:46 GMT
Article-I.D.: src.1992Apr8.160646.13661
Distribution: na
Organization: Honeywell Systems & Research Center

I'm building a new house, and would like to wire it for future smart home
(cebus, or whatever) capability.  Cost is a big concern, so I'm wondering:

1) Need two coax cables to each room.  Should I use rg-6, or the more
   common (cheaper) rg-59?  Can rg-6 be used for regular TV?

2) Need four twisted pair to each room.  Can I use plain old flat modular phone 
   cable (which is not twisted?)  If I must go with t.p., must it be
   shielded or anything fancy?

3) Would like to run fiber-optic cable also.  Is a pair to each room
   sufficient?  Can I use the very cheap plastic stuff, or is higher
   grade stuff required?

Thanks for any replies.  Please reply soon as the wallboard is going up
real soon now.

-Dave

lowry@src.honeywell.com
From: rcain@netcom.com (Robert Cain)
Newsgroups: sci.electronics
Subject: 512,000 taps!
Date: 16 Apr 92 05:45:00 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

I see adds for Harris FIR's with 512,000 effective taps!  Then it says
"High order decimating filter (up to 1024) and high tap FIR (up to 512)
on single chip".  Can anyone explain this in words.  I understand FIR's
but what is a high order decimating filter (up to 1024)?
-- 
Bob Cain    rcain@netcom.com   408-358-2007

"There are some strings.  They're just not attached."
                                                    Victoria Roberts
Newsgroups: sci.electronics
From: lfernand@ee.ryerson.ca (luis fernandes)
Subject: Re: Front panel finish
Organization: Ryerson Polytechnical Institute, Toronto
Date: Mon, 13 Apr 1992 20:16:21 GMT

There's a company called Black Lightning that makes toner cartridges for
LaserJet/LaserWriter series printers. This is no ordinary toner though, after
the image is printed on to paper it can then be transfered on to anything
(cloth (T-shirts) seems to work best) using a hand-iron (the type you use to
iron clothes with).

The October '91 issue of BYTE has a story on this. The techique was tried on
metal but the article mentions that it didn't work properly because the
surface was not prepared properly...

Basically, whatever you can print-out on your printer you can transfer on
to your front-panel.

Cartridges start at $80.00 & you can get them in different colors.

The address is:
Black Lightning
RR 1, Box 87, Depot Rd.
Hartland, VT 05048
(802) 436-3257
Newsgroups: sci.electronics
From: hermann@cpsc.ucalgary.ca (hermann)
Subject: Re: Front panel finish - related question
Organization: U. of Calgary, Alberta, Canada
	<167C59A26.STATRAA@YaleVM.YCC.Yale.Edu>
	<JVP.92Apr10113503@curan.juliet.ll.mit.edu>
Date: 12 Apr 92 18:58:21

In article <JVP.92Apr10113503@curan.juliet.ll.mit.edu> jvp@juliet.ll.mit.edu ( Jim Pieronek ) writes:
>   In article <167C59A26.STATRAA@YaleVM.YCC.Yale.Edu>
>   STATRAA@YaleVM.YCC.Yale.Edu writes:
>      this looks great, and I'd like to do something similar - but HOW can I
>      cut OVAL holes???
>
>   Being a University student in engineering, you or your ME pals should
>   have access to a half-decent milling machine.  These marvels of modern


	For anyone who hasn't got access to a milling machine, use a
jewellers saw or small hacksaw to saw out an oval slot between two holes
you've drilled at the intended ends of the slot. A set of fine files is handy
to ream and finish the rough cut. Tips: 1) centerpunch before you drill to
avoid slop, 2) cut and drill slightly less than you need, the filing will
widen the slot. 3) scribe an outline of the oval before you start. 4) _don't_
put any weight on the saw, as the blades are very delicate and fairly pricey.
If you're cutting aluminum, the weight of the saw will be enough to cut
fairly quickly. 5) use a _wood_ vice, and wrap your workpiece in cloth to
protect the finish.

	With practice you can layout, cut, and finish small pieces or kit
boxes in about an hour.

|  Mike Hermann  | hermann@cpsc.ucalgary.ca
Organized crime is analogous to organized religion: it preys on peoples'
weaknesses, generates huge profits, and is nearly impossible to eradicate.
From: jfw@ksr.com (John F. Woods)
Newsgroups: sci.electronics
Subject: Re: Electrostatic Field Promotes Hair Growth ???
Date: 8 Apr 92 15:07:19 EDT

stever@mrcnext.cso.uiuc.edu (Steve E. Robinette) writes:
>No one knows eactly why the treatment works,

But statements about suckers and birthrates come to mine.

>Can anyone "shed" any light on how this might work. Seems as though you
>could build you own quite easily instead of the $4500 a month they'll be 
                                                 ^^^^^^^^^^^^^
>charging to use it. Be interested to hear some ideas...

I think you've just isolated the operating principle.
Xref: sparky sci.electronics:8332 rec.bicycles:9203 rec.motorcycles:12904
From: dpeterso@mipos2.intel.com (David Peterson)
Newsgroups: sci.electronics,rec.bicycles,rec.motorcycles
Subject: Re: Sticky Demand Traffic Light problem solution
Keywords: inductive vehicle detectors, traffic lights
Date: 1 Apr 92 22:32:19 GMT
Reply-To: dpeterso@mipos2.UUCP (David Peterson)
Distribution: na
Organization: Intel Corporation, Santa Clara, CA

In article <1992Mar31.190727.2381@ncsu.edu> steve@bucolix.ece.ncsu.edu (Steve Garnier) writes:
>In article <peterd.702047076@pjd.dev.cdx.mot.com> 
>peterd@pjd.dev.cdx.mot.com (Peter Desnoyers) writes:
> ... stuff deleted ...

I just remembered something - when I attended U.C. Davis some 
signals around town had bike sensors, sensors in bike lanes
made to detect bicycles. Ask local athorities, maybe adjustments
could be made :^). Then again you probably would have to get
half the population to threaten a recall vote to get a city
council to do anything for the general population ;-(.
-------------------------------------------------------------------------
David Peterson 
Intel Corp., M/S SC4-69, 2625 Walsh Ave.
Santa Clara, Ca. 95052-9940
dpeterso@mipos3.intel.com
Dave Peterson
SC4-69
765-5109
dpeterso@mipos3
Newsgroups: sci.electronics
From: <alan>@me.utoronto.ca
Subject: Token Ring Drivers
Summary: Know of any drivers
Keywords: Token Ring Network
Organization: University of Toronto, Department of Mechanical Engineering
 I have two token ring cards and I want to network two PC's so that one
Distribution: sci
Date: 16 Apr 92 16:19:18 GMT

this via the serial ports of both machines, but I was wondering if
anyone knew of software that works with token ring cards to do the same
thing.  I am presently using EASYNET (a zero-slot LAN)    
I can be E-Mailed at "milner@ecf.utoronto.ca"
From: bill@hacktic.nl (Bill Squire)
Newsgroups: sci.electronics
Subject: Re: Electrostatic Field Promotes Hair Growth ???
Date: 8 Apr 92 22:18:32 GMT


        Thats quackery if I've ever heard of it before.  Heard chicken shit
works too!  There is a common heart medicine that if ground up and mixed
with alcohol and applied directly to the scalp WILL really work.  Ask your
doctor about this.  I'm shure a perscription of this preperation is alot
less than $4500 for the rest of your life!

                                                        Bill
Newsgroups: sci.electronics,rec.bicycles,rec.motorcycles
From: sagerian@delphinium.UUCP (Steve M. Sagerian)
Subject: Re: Sticky Demand Traffic Light problem solution
Originator: sagerian@apricot43
Organization: Motorola Inc., Cellular Infrastructure Group
Date: Mon, 6 Apr 1992 14:37:35 GMT

From article <-slj0+=.jps@netcom.com>, by jps@netcom.com (John Serafin):
> sagerian@delphinium.UUCP (Steve M. Sagerian) writes:
> 
>>I fact I was supprised no one mention that aluminum (sp?) wheels have no effect on the sensor at all.
> 
> Then how does an aluminum frame with aluminum wheels trip sensors?
> (It happens frequently.)
>>Stever
>> 

John, 
I responded to your query directly but I also wanted to relate my experience to the rest of rec.bicycles. As I was saying....

Yesterday, my significant other and I went out for a ride(the first near-nice day this spring). The traffic light near my home has the type of sensors/controller that this thread has been discussing so as I pulled up to it I immediately began to pay close attention to every event that happen. We were wanting to travel
straight thur the light but had the red light so we stopped in the right lane directly over the sensor. Moments later a car pulled into the left turn lane, also stopping on a sensor. The green light in the cross traffic lane turned yellow, then the left turn lane light for the car next to us, turned green,the left turn light turned yelllow but then the cross traffic light turned green! The controller never sensed that we were present on the sensor because my bike is an aluminum frame/wheels and my signific






ant others bike is also mostly aluminum. We had to cross the street by walking our bikes to the pedestrian crossing button and wait for the light again. 

Aluminum materials do not change the inductance of these sensor but most bikes are not completely aluminum either. (spokes,hubs,seat posts, handle bars, brake cables and assemblies. But even if these componets are made of ferrite materials,they may not be enough to change significantly the inductance of the sensor (enough for the traffic controller to sense your presence). 
A quick way to see if you bike parts are aluminum is to take a magnet to them...if the magnet sticks...it has some portion of it metal content is steel/ferrite material, if it does not stick then it is aluminum or plastic (who can tell now days?). 

And lastly, I wont claim that all senors are equal, I have no idea how many manufacturers of these things (auto sensors, traffic light controllers) but I suspect that there are at least two. I also suspect that for each manufacturer, the level of threshold (ie how much ferrites it takes to trigger a sensor) is different (the threshold level may be even controlable as some others in this thread have suggested..I dont know). 

enough..Steve
From: ericc@arco.com (Eric Chang)
Newsgroups: sci.electronics
Subject: Help on reference (magnetometer)
Date: 13 Apr 92 20:47:11 GMT
Distribution: usa
Organization: ARCO

I posted an article several days ago asking if anyone has a circuit for a 
magnetometer which could discern small perturbations in the earth's magnetic
field.  I did not receive too much specific information on this, but I did
find a reference to a circuit in "The Encyclopedia of Electronic Circuits"
by Rudolf Graf.  Unfortunately, to build the two detection coils, the original
reference is required.  It is in Hands on Electronics, which is hard to find
in libraries.  I think the issues are May/Jun '89.  Does anyone know where to
find this periodical or articles contained therein.  Please email; I'll update.
Thanks.       Eric
From: gsulliva@enuxha.eas.asu.edu (Glenn A Sullivan)
Newsgroups: sci.electronics
Subject: Re: RF Preamplifier design
Summary: System analysis of The RF preamplifier design
Keywords: RF preamplifier design
Date: 11 Apr 92 04:17:30 GMT
Distribution: sci
Organization: Arizona State University

***One full page of noise floor & feedback loop calculations, at the end.***

In article <1992Apr9.184230.13126@acuson.com>, kumar@acuson.com (Kumar Neelakantan) writes:
> I am looking for a design or names of companies/consultants who could design
> an RF preamplifier with the following specs:
> 
> Gain: 30 dB
> Input Signal Dynamic Range: 2 mV - 1.2 V pk-pk ( ~55dB )
> Max Output Voltage: 36 V pk-pk
> Frequency Response: Flat (100 KHz - 10 MHz) with +- 0.1 dB passband ripple
> 			- 3dB Frequency: 20 MHz
> Impedance of input load connected to preamp: 0.5 - 1 Mohm, 3-5pF
> Output Impedance: 50 ohms	
==>  [ 18volts peak/50 Ohms = 300 milliamps ]
> Output Spectral noise density: 0.1 microVolts/sqrt. Hz with input
> of preamp terminated in 50 ohm load  [
==> The thermal noise in one Hertz Bandwidth is -174dBm. 
  Given 30dB gain, we have -144dBm noise power per Hertz at output.
  Since 0dBm is 223millivolts RMS @50 Ohm the required 0.1microvolts is a
  factor of 2.2 million weaker, or -127dBm. We are thus allowed an amplifier
  noise figure of -144 to -127, or 17dB, at 50 Ohm source resistance.

  You provide no phase response requirements, or distortion requirements,
  or short-circuit requirements, or what the reactance of the load will be.
  There is a conflict between the 3DB point of  20MHz, and only being
  down 0.1dB at 10MHz.

  To get a response accurate to 0.1dB, given 30dB closed loop gain,
  (assuming 0.1dB is about 1%, in absence of remote node 'rnews' 
  allowing separate SHELL to run LISP to compute 0.1dB)
  we need open-loop gain of 30dB + 20*log10( 1/1%) = 30 + 40 = 70dB, or 3100.
  Given a 10MHz max freq to hold the 0.1dB, ignoring any benefits of
  phase shift in generating error signals, we need GainBandwidth of
  31GigaHertz. If done by one feedback loop.

  Probably should use two loops. Try closed-loop gains of X10 and X3.
  The X10 only outputs 6 volts peak-peak. The X3 outputs the 18volts PP,
  and must include the time-delay/phase-shift of a 300milliamp driver.

> If you have any info call me at (415)694-5722 or send me e-mail to
> kumar@acuson.com
> kumar neelakantan 


Allen Sullivan
Designing RF/video circuits for Go-Video, Scottsdale AZ
CS PhD student Arizona State Univ
Developing LISP methods for analog circuit synthesis
From: thomas@sunshine.Kodak.COM (Thomas Kinsman)
Newsgroups: sci.electronics
Subject: WANTED: Help with SpectroPhotometer.
Keywords: SpectroPhotometer Power Cord
Date: 7 Apr 92 17:14:00 GMT
Organization: Eastman Kodak Co., Rochester, NY


    SITUATION:

    I have a Digital Spectro-photometer, Perkin-Elmer, 602, Model  062-0001,
    part #333-0031.  It is made by Hitachi Ltd., Japan, in or around 1970.

    PROBLEM:

    I need to build a power supply for it.  It requires a power cable,  with
    a seven pin connector on it.  The pins are in a hex pattern.

    WANTED:

    The pin-out and voltage specs for the power cord?  Any ideas on where  I
    can  find  them?  Perkin-Elmer purchased this from Hitachi and then sold
    it in the US as their own product.  Perkin-Elmer  refuses  to  recognize
    this as one of their own.

    AUTHOR:

    The preceeding "challange" was posted for my brother.  If you  have  any
    information  on this, please either contact me (thomas@ssd.kodak.com) or
    phone Edward Kinsman at 716/377-7990.  Thank you for your help  in  this
    matter.


    #include <standard disclaimer>


--
thomas@acadia.kodak.com    Voice: 716/477-2831(w)	     Fax: 716/722-0160
Thomas B. Kinsman, Eastman Kodak Co., Flr 3, Bldg 65, RL, Roch., NY 14650-1816
From: "wayne kelso" <wayne.kelso@canrem.com>
Newsgroups: sci.electronics
Subject: portable phantom powe
Date: 14 Apr 92 01:43:34 EST
Reply-To: "wayne kelso" <wayne.kelso@canrem.com>
Distribution: sci
Organization: Canada Remote Systems

I have a pair of Neumann U-87's that I would like to take out into the 
field with a portable DAT machine. Could someone advise me on a suitable 
battery pack that I could use to build a power supply. Is there anyone who 
makes a commercial version of this?

Wayne.Kelso@canrem.com

---
 * Freddie 1.1 * Sticks and Stones may break my bones, so quit it.
--
Canada Remote Systems  - Toronto, Ontario/Detroit, MI
World's Largest PCBOARD System - 416-629-7000/629-7044
From: 2frlclover@kuhub.cc.ukans.edu
Newsgroups: sci.electronics
Subject: Dick Smith Electronics
Date: 12 Apr 92 19:43:08 CDT
Organization: University of Kansas Academic Computing Services

Does anyone know if Dick Smith Electronics still exist ?

Mike
From: litwack@dccs.upenn.edu (Mark Litwack)
Newsgroups: sci.electronics
Subject: micro-stepping
Date: 15 Apr 92 22:30:16 GMT
Organization: University of Pennsylvania

I've got some questions on micro-stepping
a stepper motor.

First, how is it accomplished?  My first guess
is that you would step the current in the active phase
down a little bit as you stepped up the current in
the next phase.  This would make the armature sit
rotationally between the two phases.  Is this right?

If so, is there a linear relationship between the current
in the two phases and the rotational position?  I.e.,
if I applied 2/3 the current to phase A and 1/3 the current
to phase B, would the armature sit 1/3 step away from A?
If not, I guess I would have to use some kind of rotational
feedback.

Any good suggestions for micro-stepping controllers
(chips, hybrids, board level)?

Thanks,

-mark
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.electronics
Subject: Re: Electrostatic Field Promotes Hair Growth ???
Date: 8 Apr 92 16:13:44 GMT
Organization: University of Georgia, Athens

In article <1992Apr8.070856.10703@ux1.cso.uiuc.edu> stever@mrcnext.cso.uiuc.edu (Steve E. Robinette) writes:
>Has anyone heard of this??? It seems a company in Canada has designed a device that looks like a beauty salon hair dryer. The hood has four pairs of
>positively and negatively charged electrodes, which are powered by a 12-volt
>battery. While the patient sits under the hood for twelve minutes, his/her
>head is surrounded by an electrostatic field of positive and negative charges
>which stimulate hair growth. No one knows eactly why the treatment works, but when a patient takes the treatment once a week for a period of one to two years, hair comes back. This is a treatment not a cure. It must be continued for life
>
>Can anyone "shed" any light on how this might work. Seems as though you
>could build you own quite easily instead of the $4500 a month they'll be 
>charging to use it. Be interested to hear some ideas...
>

I very very much doubt that it works.  At $4500 a month, it sounds like a
scheme for separating fools from their money.

Ever heard of SCIENTIFIC MEDICINE, folks?



-- 
==========================================================================
Michael A. Covington, Ph.D. |  mcovingt@uga.cc.uga.edu  |  ham radio N4TMI
Artificial Intelligence Programs | U of Georgia | Athens, GA 30602  U.S.A.
==========================================================================
From: agulhati@willamette.edu (Ashish Gulhati)
Newsgroups: sci.electronics
Subject: Re: Front panel finish - related question
Date: 13 Apr 92 03:01:55 GMT
Article-I.D.: willamet.1992Apr13.030155.23208
Organization: Willamette University, Salem, OR

Why not drill 2 largish holes and use a nibbler to connect 'em, giving a
pretty neat oval. 

I'm sure (although I haven't tried) a nibbler (handy tool) could be used to
directly cut an oval along a predrawn boundary too.

Ashish
Xref: sparky sci.electronics:8337 sci.physics:6705