HDTenEightyP/NetNews huggingface dataset:
From: v064mb9k@ubvmsb.cc.buffalo.edu (NEIL GANDLER)
Newsgroups: sci.electronics
Subject: A much better power inverter design
Date: 11 Sep 92 01:41:00 GMT
Organization: University at Buffalo
News-Software: VAX/VMS VNEWS 1.41


   I am a sophomore engineering student and have been researching and
trying to develop a new type of car amplifier that runs cooler and
the taim was at the power supply. 12v simply is not enough voltage
to power speakers to large amounts of power unless multiple amps
and speakers are used. So most manufactuers use mosfet power supplies
that step up the 12vdc to higher levels by first providing a 60hz
oscillating signal and using power mosefets to switch the 12v power
to a step up power transformer which results in a larger square wave ac
voltage output. This is rectified and the result is a dual polarity
high voltage dc power supply for power amplifiers. But the mosfets although
amazing devices have internal resistances that cause them to heat up a lot
under heavy current loads. So I tried a mechanical method using 2 high
speed quality relays. The design amazingly worked with little problems,
like noise from the 60-hz modulated relays, a small amount of magnetic
intereference which can be solved and slightly warm relays. The only
major problem I can see is reliabilty. How many cycles can a relay take
before they burn out, thats the only question. I must do more work and
improve on this. Another small problem is irregularity, relays are not
perfect bounceless switches and spikes and irregularities on the scope
show up frequently on the square wave ac output. I have yet to try
this with a power amplifier. Overall the major advantage is cost including
no expensive mosfets, no large metal heatsinks and little waste and its
small size makes it perfect for a car. The only real source of heat is in
the step up transformer. I am not an enginneer yet and I doubt that I
found something new. I am open to any questions, opinions and comments
and would like to know if I have something here. Thankyou

Neil Gandler
From: rwb@alexander.VI.RI.CMU.EDU (Robert Berger)
Newsgroups: sci.electronics
Subject: Re: Radio Interference for R/C flyers
Date: 5 Sep 92 06:03:40 GMT
Article-I.D.: cs.Bu3Cu4.ACy.2
Distribution: na
Organization: School of Computer Science, Carnegie Mellon

> Is it possible that the mixing occurs when the signal from one  
transmitter 
> is induced on the other transmitter's antenna? This signal finds it's  
way 
> through the RF amplifier output filter and into the RF amp. where it  
mixes 
> with the native transmitter frequency.  The resulting cross products are 
> then amplified and transmitted?  

That's it precisely.

IM can occur in any nonlinear circuit; even if it's just two pieces of
metal with a corroded junction between them. However, a transmitter is
one of the most common places, since a nonlinear (Class C) amp is  
connected directly to an antenna. Commercial TV transmitters often have
ferrite isolators to prevent this.
Newsgroups: sci.electronics,rec.radio.amateur.policy,alt.folklore.urban
From: res@colnet.cmhnet.org (Rob Stampfli)
Subject: Re: Is this legislation for real?
Organization: Little to None
Distribution: usa
Date: Tue, 8 Sep 1992 03:41:58 GMT

>BUT it did set a future date (6 months I think) after which 
>manufacturers would have to have eliminated any cellular frequency
>coverage from any receiver they manufactured.  There was no exception
>for test equipment, etc.

How about for cellular phones?
-- 
Rob Stampfli  rob@colnet.cmhnet.org      The neat thing about standards:
614-864-9377  HAM RADIO: kd8wk@n8jyv.oh  There are so many to choose from.
From: Desiree_Bradley@mindlink.bc.ca (Desiree Bradley)
Newsgroups: sci.electronics
Subject: Re: Filtering TV Commercials
Date: 5 Sep 92 21:05:07 GMT
Organization: MIND LINK! - British Columbia, Canada
Distribution: world

I\ Gordon Hlavenka says:

This is not _always_ the case.  In fact, I recently watched a
commercial which appeared to have been deleberately processed in such
a way as to make the words _difficult_ to understand.  The overall
volume (composite power) was reduced, and the high frequencies were
noticeably rolled off.  The product?  Beltone hearing aids :-)
(Their 800 number was on the screen in large print throughout...)


--
----------------------------------------------------
Gordon S. Hlavenka           cgordon@vpnet.chi.il.us
  Don't forget:  Dave Barry/Joe Walsh in November!



They probably turned down the volume to make people have doubts about their
hearing.

Desiree Bradley
Newsgroups: sci.electronics
From: elgreco@milton.u.washington.edu (Jared Vogt)
Subject: what kind of nor gate
Organization: University of Washington
Date: Sat, 5 Sep 1992 04:17:13 GMT


I am working on a project involving MIDI.  I would like to take 16 inputs
and "Y" them down to 1 output.  I don't want an active merge as this is too 
complicated, I want a passive system where only one input would be active
at any one time.  (ie.  no fancy electronics to insure that the integrity of 
two serial signals is kept)  I have figured out that with a combination of 
nor and nand gates I can achieve my purpose logically, now how do I do it
practically.  When I open up my Mouser Electronics catalogue I find that there
are several different nor gates (4000, 74HC, 74LS low power schottky, 74HCT 
etc....)  What the heck do I use.  How do I figure it out?  MIDI is (of course)
a binary signal running at 31.25K baud - current loop, 5mA, logic 0 is current
on (does this mean negative logic?).
I tried this by hardwiring it together, but this caused a backwash into the 
audio.  I then made it with a ten position switch so that only one signal was
physically connected at one time.  I would like this new project because I 
would not have to switch to any input, rather using that input would - in
effect - switch itself on.  In addition, I would like to add some sort of
LED in the system so that when an input was active the LED would indicate
which of the sixteen it was.
I have been told that running the signals through 4 quad dual input nore 
gates and running those outputs into a nand gate would do the trick
What do I need, where do I get the parts and how do I put this together.
Thanks in advance for the advice.
Also any advice on a simple (ie for the electronic idiot) book with simple
explinations on these sorts of things?

Jared
elgreco@u.washington.edu

Newsgroups: sci.electronics
From: jeff344@lerc.nasa.gov (Jeff Berton)
Subject:  Help!  Thermostats and Beer!
Reply-To: jeff344@voodoo.lerc.nasa.gov
Organization: NASA Lewis Research Center, Cleveland, OH
Date: Thu, 10 Sep 1992 20:38:56 GMT

Part of brewing beer at home involves heating a barley malt and water "mash"
at certain temperatures for certain time intervals.  This converts the malt
starches to fermentable sugars.  Needless to say, standing over a pot on a
stove with a thermometer and stirring spoon for a couple of hours is the
least desireable part of brewing!
 
I'd like to get some sort of feedback-loop control system that reads the 
temperature of the mash from a thermocouple and turns my electric stove on
and off.  Are there any science supply mail-order companies that sell
thermostats like this?  I called Edmund Scientific's 800 number for their
catalog.  According to the machine I spoke to, I only have to wait 4 weeks.
Any other recommendations?

-------- Jeff Berton;  jeff344@voodoo.lerc.nasa.gov;  (216) 977-7031 --------
--------- Aeropropulsion Analysis Office, NASA Lewis Research Center --------
------------- "If headquarters is interested, we're interested!" ------------
From: roger@hpnmdla.sr.hp.com (Roger Petersen)
Date: Sun, 13 Sep 1992 02:01:38 GMT
Subject: Re: <<<<<FOR SALE  68030 33MHz. - $300  shipping paid by me
Organization: HP MID Excess Division, Santa Rosa CA
Newsgroups: sci.electronics

In sci.electronics, rubin@glockenspiel.cis.ohio-state.edu (Daniel Rubin) writes:

| Here are the microprocessor prices directly out of the 1992 JDR Microdevices
| catalog #21 !

Aaack!  These prices are outrageously high!
Perhaps it was a January '92 catalog... that might explain a bit of the
extra $.

Figure a drop of 3% to 5% a month, on parts that are sold in 
competitive markets (like the '386).

I'll throw out some August '92 prices below...

| 68000 $6.95 <- wow very cheap considering

Sounds reasonable.  $3 to $15, depending on speed and package.

| 68020 $189.95

Should be $20 to $100, depending on speed and package (PLCC vs PGA)

| 80286-8Mhz  $12.95

?

| 80386-20Mhz  $ 269.95
| 80386-25Mhz  $ 289.95
| 80386-33Mhz  $ 299.95
| 80386-40Mhz  $ 329.95 <- you are getting a hell of a deal on that board!

These are currently available from $79 to $109 from many places.
AMD has tried to underprice Intel, successfully.  Great for consumers.

| 80486-33Mhz  $ 599.00
| 80486-50Mhz  $1199.00 <- Ack!

My computer magazine here shows $400-$600 on the 486DX line,
and $100-$150 on the 486SX.  On the '486SX, Intel is trying
to draw away '386 sales from AMD, by pricing the 486SX right around
'386 prices.

Roger Petersen
roger@sr.hp.com

Newsgroups: sci.electronics
From: klimasewski@fccvde.enet.dec.com (My name is...)
Subject: PROM PRO 8 software
Organization: Digital Equipment Corporation
Date: 14 SEP 92 12:00:17    



I am looking for some software to work with a PROM PRO 8 prom programmer.


                                      thanks,
                                       Ken
From: kolstad@cae.wisc.edu (Joel Kolstad)
Newsgroups: sci.electronics
Subject: LCD displays, again
Date: 14 Sep 92 16:37:11 GMT
Organization: College of Engineering, Univ. of Wisconsin--Madison

My last post seems to have left some things unclear, so let me try to clear
them up...

The LCD displays that I'm talking about are sold by Timeline Inc., at (800)
872-8878.  I also noticed that they now sell the 16x1 displays at 3 for $25...
$8.33 each.  They also have a little notice "Some models are blacklit,
call for more details..." so they must now be aware of this "feature" too.

All Electronics sells, for $3.50, a back light (electroluminescent panel and
inverter) from an early model of a Citizen hand held LCD TV.  The inverter from
this back light can be used to power the back lights of many LCD displays,
and it a lot cheaper than the upwards of $15-$20 that many places want for
an inverter alone.

I hope that clears some things up... I've been unable to respond to everyone's
mail messages because CAE's mail server here isn't the greatest and some
mail has bounced.

						---Joel Kolstad
Xref: sparky sci.electronics:15500 rec.radio.amateur.policy:1624 alt.folklore.urban:23302
Newsgroups: sci.electronics,rec.radio.amateur.policy,alt.folklore.urban
Subject: Re: Is this legislation for real?
From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Date: Fri, 11 Sep 1992 14:22:00 GMT
Reply-To: frank@rover.uchicago.edu
 <1992Sep6.070933.16476@porthos.cc.bellcore.com> <1992Sep11.003121.13086@mole-end.matawan.nj.us>
Distribution: usa
Organization: Joint Center for Radiation Therapy
Summary: Section 1706
News-Software: VAX/VMS VNEWS 1.41    

In article <1992Sep11.003121.13086@mole-end.matawan.nj.us>, mat@mole-end.matawan.nj.us writes...
>(Flame on!)
>Section 1706 of the 1987 (86?) Tax Reform Act was pushed through by
>`Bedfellow' Moynihan, ...

	There is no distinctly American criminal class - except
	Congress. - Mark Twain

   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   | |_) _   Of all the wild beasts of land or
                                   | \|_)  sea, the wildest is woman.
    "Birthplace of Softball"          |_)  Menander (342?-291? B.C.)
From: schuster@panix.com (Michael Schuster)
Newsgroups: sci.electronics
Subject: Re: Cassette recorder questions
Date: 9 Sep 92 11:53:47 GMT
Distribution: usa
Organization: PANIX Public Access Unix & Internet, NYC

In article <1992Sep9.021229.20646@athena.cs.uga.edu> mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
>(1) Are the counters on cassette tape recorders standardized?
>That is, do they all read the same numbers for the same positions?

Not at all.

>(2) Where can I get a test tape for adjusting alignment and speed?
>Minimally, it should have a tone at a known frequency recorded on it.

There are many of these available, ranging from relative inexpensive to
very expensive. The tapes made by Magnetic Reference Laboratory
(415-965-8187) are reputed to be the best.

A more cost effective alternative is the TEAC MTT-114 which is used by many
Japanese cassette deck manufacturs for azimuth setup at the factory.
It costs $38 from TEAC's parts department (213-726-0303 x720 or x757).
It contains a 10 KHz tone.

Be aware that to use this properly you need an oscilloscope, and preferably
one having an x-y mode. However, you can get pretty close using your
hearing and a couple of tricks.


>
>
>
>-- 
>+ Michael Covington - Artificial Intelligence Programs - U of Georgia - USA 
>+ Unless otherwise noted, these are private opinions, not official statements.
>+ VOTE NO GEORGIA LOTTERY - we need not imitate mistakes of other states.


-- 
_______________________________Mike Schuster________________________________
NY Pub. Access UNIX/Internet: schuster@panix.com | 70346.1745@CompuServe.COM
The Portal (R) System: schuster@cup.portal.com   | MCI Mail,GEnie: MSCHUSTER
From: dino@inqmind.bison.mb.ca (Tony stewart)
Newsgroups: sci.electronics
Subject: Re: Phone circuit projects...
Keywords: HOLD IN-USE PHONE
Date: Mon, 14 Sep 92 20:12:40 CDT
Organization: The Inquiring Mind BBS  1 204 488-1607

djk@world.std.com (Dan J Keldsen) writes:

> I'm trying to find a book or books or just schematics from some kind soul,
> that would enable to me to have a 2-line system (modifying a 1-line phone)
> that would have a light for the ringer (on each line), and same light
> would light (and stay lit) while that line was in use. So, I need plans
> for a 2-line HOLD circuit, and plans to light da light of a line in-use. BTW,
> the in-use light should work if an extension phone is in use also, not just
> the attached phone to said circuit.
> 
> ----------------------------------------------------------------------
> Dan Keldsen			Working on a Brain-to-
> djk@world.std.com		MIDI convertor...
> Somerville, MA			Anybody willing to sport
> BERKLEE College of Music	the necessary "elective surgery" ??
> ----------------------------------------------------------------------
> 

You can buy fancy speaker phones with timers,clocks and memory which have 
2 line capability for about $50. the hold feature should only cost a few 
bucks with led's to monitor active lines (and suitable resistance)
hold cct is only a resistor to maintain the voltage low. On hook is 
usally 48V, off hook is 12V 1phone 6V 2 phones etc approx.

dino@inqmind.bison.mb.ca
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607
From: agodwin@acorn.co.uk (Adrian Godwin)
Newsgroups: sci.electronics
Subject: Re: Try this with your DMM
Date: 10 Sep 92 12:53:57 GMT
Organization: Acorn Computers Ltd, Cambridge, UK

In article <5170220@hplsla.hp.com}  tomb@hplsla.hp.com (Tom Bruhns) writes:
} With regard to asking a DMM to measure its own battery voltage, 
} Mark-Tarbell@suite.com writes:
} 
} } Any ideas?
} 
} Sure.  Charge a cap with the battery voltage and measure it.  
} Linear Technology even makes a special switch IC to do this sort
} of thing gracefully, if you need to do it often.  It helps if
} the cap has low leakage and the DMM has an essentially infinite
} input impedance on the required range.  Try a time constant of
} DMM input R * C of 100 times as long as it will take you to read
} the DMM, for a 1% error.
} 
} Trying to measure the battery directly is dangerous at best, since
} you are shorting out some part of the guts of the DMM when you hook
} the input leads back to the battery.

It's possible that there's a fixed offset between one battery terminal
and one meter lead, so you can ignore that 'common' lead and take
a measurement on each battery terminal _using_only_the_'hot'_meter_lead.
Take the difference between the two readings as the battery voltage.

The 'hot' meter lead isn't necessarily the obvious one, but it may be - 
I tried the red probe on a Fluke 77, and got +3.1V on the positive terminal
and -5.6 on the negative. Checking the battery independently showed
8.7V was correct.

And I agree with Tom - using the wrong probe might damage the DMM's guts, 
so be warned !

-adrian




-- 
Adrian Godwin : agodwin@acorn.co.uk : adrian@fangorn.demon.co.uk : g7hwn@gb7khw
ObDisclaimer  : I believe this rubbish .. don't imagine that anyone else does.
From: michael@vk2bea.UUCP (Michael G. Katzmann)
Newsgroups: sci.electronics
Subject: Re: Answer to BNC question (with an actual REFERENCE!)
Keywords: BNC, TNC, name origin
Date: 14 Sep 92 14:23:15 GMT
Reply-To: michael@vk2bea.UUCP (Michael G. Katzmann)
Organization: Broadcast Sports Technology, Crofton. Maryland.

In article <1992Sep11.183503.9741@vela.acs.oakland.edu> lmbrown@vela.acs.oakland.edu (lmbrown) writes:
 >
 >You can find the origin of the names of BNC, TNC, etc in an 
 >article entitled "A Designer's Guide to RF Connector Selection,"
 >RF Design, September/October 1980.
 >
 >BNC stands for bayonet Neill-Councelman, named after Paul Neill
 >of Bell Labs and Carl Concelman.
 >

The 199 Microwave journal State of the Art reference has an an article
"Microwave Coaxial Connector Technology" by Mario A Maury, Jr which states:

	"Then, as smaller coaxial cables became available, the BNC connector
was developed jointly by Neill and Concelman, hence the N and C and the B for
baby because of its size."


I don't know which is right, perhaps it just assumed to be bayonet because
of its construction. The reference for this part of the article was:
	"Coaxial Transmission Lines...Connectors, and Components: A 
		U.S. historical perspective," IEEE Trans on MTT, Sept 1984
			pp 970-982.




-- 
Michael Katzmann	  >	Broadcast Sports Technology Inc.
~~~~~~~~~~~~~~~~	 <	Crofton, Maryland. U.S.A
Amateur Radio Stations:   >
NV3Z / VK2BEA / G4NYV	 <	opel!vk2bea!michael@uunet.uu.net
Newsgroups: sci.electronics
From: peterd@pjd.dev.cdx.mot.com (Peter Desnoyers)
Subject: Re: CSMA/CD on RS232?
Organization: Motorola Codex, Canton, Massachusetts
Date: Tue, 15 Sep 1992 21:01:12 GMT

smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:

>In article <1992Sep15.150015.7409@sbctri.sbc.com>, tadams@sbctri.sbc.com (Tom. Adams 529-7860) writes:
>> I was wasting time in a meeting, and came up with an idea that seems
>> interesting to me.  Consequently I'm sure it's been done, or more likely
>> been shown to be just incredibly stupid. :)
>> 
>> I'd like to connect multiple devices to an RS232 line, buswise.  All devices
>> would either be programable, (i.e. PC's) or be frontended by a (cheap)
>> microprocessor.  I'm wondering if CSMA/CD is a reasonable way to manage 
>> very low speed bus contention.

You could do CSMA/CA, and get away with using stock hardware. The idea is
that you send a short "reservation" packet, and require the destination
to respond to it. If you don't get a response within a short time, you
assume a collision and back off. The advantage is the lack of special-
purpose hardware; for instance, you could use PC serial ports.

See the description of the Localtalk protocol in "Inside Appletalk" for
more details - that's the scheme they use, probably for cost reasons.

				Peter Desnoyers
-- 
Newsgroups: sci.electronics
From: capnal@aqua.whoi.edu (Al Duester)
Subject: Tesla coil book source
Organization: Woods Hole Oceanographic Institution
Date: Fri, 11 Sep 92 02:49:08 GMT


While I can't find the catalog itself in the piles of my life
that abound, Lindsay Publications Inc., PO Box 538, Bradley
IL 60915-0538  (815) 935-5353 has at least one, and possibly
more, books on Tesla coil design & construction. They also have
lots of other neat books on casting, machine tools, embalming,
chemistry, explosives, food, etc. Really worthwhile catalog
to get.
From: ted@nmsu.edu (Ted Dunning)
Newsgroups: sci.electronics
Subject: Re: Question about origin of name of BNC connector
Date: 9 Sep 92 16:42:26 GMT
Reply-To: ted@nmsu.edu
Organization: Computing Research Lab



In article <1992Sep8.231210.26194@panix.com> schuster@panix.com (Michael Schuster) writes:


   I'm not sure of the spelling, but BNC is the Bayonet version of the
   Neil-Councelman Conenctor. TNC is the Threaded version of
   same.



the last time this wandered around the net, the spelling of the second
name was concelin.

in any case, Neal also designed the N connector.

--

REALLY, instead of hyping low impact soles, I think what we need
are more low impact souls.
					Greg Jahn
From: rkarlqu@hpscit.sc.hp.com (Rick Karlquist)
Date: Fri, 4 Sep 1992 23:19:47 GMT
Subject: Re: Filtering TV Commercials
Organization: Hewlett-Packard, Santa Clara, CA
Newsgroups: sci.electronics

In sci.electronics, johna@psdcae1.gvg.tek.com (John Abt) writes:

> The bottom line is this: The broadcast TV industry makes its
> money from commercials. If there were any reliable way of 
> defeating that process, you can rest assured that it would be
> fixed in rather short order.

> Actually, something that would prove more useful, especially
> given the upcomming presidential mud fest, is the bullshit filter.

> John Abt

Actually, now that all new TV sets will be closed-caption ready
and commercials are starting to be captioned, you should be able
to build a system that monitors the ASCII in the captions and
looks for keywords (such as tradenames) to eliminate commercials.
You could also eliminate "bullshit" by adding keywords relating
to what you define as such.  I wish I could search for keywords
relating to abortion and gun control and filter talk shows so
I wouldn't have to hear the same old arguments on those topics
rehashed for the nth time.

It will be interesting to see what the TV industry does to 
prevent this scheme from working.  They can't stop captioning the
commercials because then you would simply search for absense of
captioning.

BTW, I think this may be the reason that "electronic newspapers"
have never caught on, because you could filter out advertisements
with software.

Rick Karlquist
rkarlqu@scd.hp.com
From: johnwitt@cdrom.engin.umich.edu (John P Wittkoski )
Newsgroups: sci.electronics
Subject: "Typical" propogation delays
Date: 15 Sep 92 21:37:50 GMT
Organization: University of Michigan Engineering, Ann Arbor
Originator: johnwitt@cdrom.engin.umich.edu


In data books for logic devices (and for other things as well) there are AC timings listed - min, max, and sometimes typ.

I realize that typ is like an "average" of the parts they test.

Now, say I have a single specific part in my possesion, (say a 74ls04) and say it runs at the same temperature and humitity all the time. Will the propogation delay for that specific single chip almost always be the same? Or is it possible that one second, the delay through the chip is closer to the min, and at some other second, it is closer to max? Or will it almost always be close to the same value for that specific chip?

Just curious.

Reply by e-mail or posting, whichever is easier for you.

	--John Wittkoski
	  University of Michigan
	  johnwitt@engin.umich.edu
Organization: Senior, Physics, Carnegie Mellon, Pittsburgh, PA