HDTenEightyP/NetNews huggingface dataset:
From: schaefer@sal-sun49.usc.edu (Peter Schaefer)
Newsgroups: sci.electronics
Subject: Re: Power Amplifiers
Date: 21 Jan 1993 14:28:47 -0800
Organization: University of Southern California, Los Angeles, CA
Distribution: world
NNTP-Posting-Host: sal-sun49.usc.edu


In article <15579.2b5e3cf6@ohstpy.mps.ohio-state.edu>, garland@ohstpy.mps.ohio-state.edu writes:
|> In article <1jkrndINNrht@usenet.INS.CWRU.Edu>, ah335@cleveland.Freenet.Edu (Richard Banks) writes:
|> > In a previous article, schaefer@sal-sun93.usc.edu (Peter Schaefer) says:
|> > 
|> >>
|> >>Could anyone out there please give any recommendations on books or other such
|> >>literature regarding large-scale power amplifier design? Thanx in advance.
|> >>					Peter Schaefer
 
|> How about defining your needs a bit more precisely? Do you want 1MW high
|> frequency rf designs, 10kW rf induction furnance designs, ultrasonic amplifier
|> designs for medical uses, 1kW audio amplifiers for rock concerts, UHF
|> television 300kW designs? Or are you interested in motor controller amplifiers,
|> wideband pulse amplifiers for radar applications? Do you need amplifiers with
|> 50ohm input/outputs? Voltage sources? Current sources? Give us some guidance
|> and maybe we'll all be able to offer suggestions.
|> 
|> Jim
I need info on designing amplifiers in the hundreds-of-watts range for
powering the reference windings of a constant-velocity AC servomotor.  I need
to deliver 3 amps, 26volts, 400Hz.  I'm also interested in info on amplifiers
for audio and for other motor control apps.  
					Pete Schaefer
From: gerald.belton@ozonehole.com (Gerald Belton) 
Newsgroups: sci.electronics
Subject: My TV is in a funny spot.
Date: 21 Jan 93 13:36:00 GMT
Distribution: world
Organization: The Ozone Hole - SKYDIVE New Orleans! - (504)891-3142 16,800 bps
Reply-To: gerald.belton@ozonehole.com (Gerald Belton) 

>If I do turn it to the UHF, and put it on 14 or 15 I can watch SATTELITE
>TV!  My neighbour has a dish, and I seem to be getting some sort of
>deflection onto my set.  There is a loop included with the TV that is attat
>to the UHF part.  Moving it can make the signal better or worse.  I get
>a good picture and sound.  It does get worse somedays (unwatchable) and
>varies to extremely watchable (very little snow, no interference on
>sound) others.  I also can watch him switch satellites/channels and
>actually see the numbers of the channel/satellite he wants.  He
>also owns a Sega Genesis BVK>and I can watch him play games on it. :-)

A while back there was a company marketing something called the "VCR
RABBIT."  It is/was basically a small UHF transmitter that would
broadcast the output from your VCR so you could watch it on other TV
sets around the house.

I bet your neighbor has one of these.  He probably has a switch box with
the satellite reciever, cable box, VCR, and Genesis game as inputs.  The
output goes to the transmitter and his main TV.  Your TV is picking up
his signals.

---
 . SLMR 2.1 . Member:  International Brotherhood of Tagline Thieves.
                                                                                                           
----
+=====================================================================+
| The Ozone Hole - SKYDIVE New Orleans! - (504) 891-3142 HST/DS 16.8K |
| 3 Nodes <> USA Today <> Boardwatch Online <> 10 Gigs <> 73900 Files |
+=====================================================================+
From: u9222774@sys.uea.ac.uk (A. Moyns)
Newsgroups: sci.electronics
Subject: Re: 110V -> 220/240Vconversion for appliances
Keywords: Voltage conversion
Date: 21 Jan 93 19:58:57 GMT
Organization: UEA School of Information Systems, Norwich, UK.

apm@kaa.ee.umist.ac.uk (Paul Marriott) writes:

>I am shortly moving to Canada and have quite a bit of UK electrical
>equipment to take. Obviously, this is rated at 240V, 50Hz. Whats the
>deal with transformers to convert 110->240? What sort of power ratings
>are available? Enough to power a 3KW kettle? Or is it better to buy
>stuff over there that is rated at 110V?

You're asking for serious problems here.  3kW, you're talking big transformers!

>Also, is it possible to wire two outlets in series to get 220V? Or is
>that asking for trouble!?

Not only asking for trouble, but also impossible.  You can't increase the voltage
by just connecting sockets together.  Step-up transformers required, I'm not
sure if they're available for domestic use though.

>Another question is light bulbs. Are 110V bayonet fitting bulbs available
>or Edison Screw to bayonet converters? 

Not quite sure about what you're after here - try Maplin electronics catalogue.


--

Andrew Moyns
Mail - u9222774@sys.uea.ac.uk
From: bote@access.digex.com (John Boteler)
Newsgroups: sci.electronics
Subject: Re: PC BOARD ETCHING QUESTIO
Date: 21 Jan 1993 12:05:14 GMT
Organization: Express Access Public Access UNIX, Greenbelt, Maryland USA
NNTP-Posting-Host: access.digex.com

ai980@cleveland.Freenet.Edu (Dennis Melcher) writes:
>Remember that the quality of negative will not only depend on the printers
>ability to process the film, but also how good the artwork is.
>I've had no problems with artwork generated by a laser printer.
>Also don't supply artwork that's been xeroxed... you'll get fuzzy edges
>and have alot of touch-up work to do.

Better yet, ask for an orthographic print. The orthographic paper
either prints black or white, no gray scale.

Electronic methods are available. The board description can be
sent to the board maker in electronic form and the board maker
can work his magic without the possibility of physical deterioration
of the image in intermediate steps. This assumes you lay out
the board electronically.

-- 
bote@access.digex.com (John Boteler) 
This week's usenet malapropism: foo, foo-foo
foo=general meaningless expletive, not deleted
foo-foo=the kind of sweet drinks they serve at Armand Chicago Pizzaria
From: wtm@uhura.neoucom.edu (Bill Mayhew)
Newsgroups: sci.electronics
Subject: Re: Auto "tow" sensor idea needed
Date: 26 Jan 93 14:50:12 GMT
Organization: Northeastern Ohio Universities College of Medicine

I'd attach a magnet and reed switch or a variable reluctance sensor
to the wheels.  If your car has antilock brakes, you might be able
to mount a second variable reluctance sensor to pick up movement of
the toothed ring.  Don't try to piggyback off the original ABS
system, as you're playing with safety related components there.  If
you don't have ABS, you might be able to grab the toothed rings
and/or sensors at the local bone yard.  It'd be a fun electronics
project.


-- 
Bill Mayhew      NEOUCOM Computer Services Department
Rootstown, OH  44272-9995  USA    phone: 216-325-2511
wtm@uhura.neoucom.edu (140.220.1.1)    146.580: N8WED
From: dhi00@ccc.amdahl.com (mofo )
Newsgroups: sci.electronics
Subject: sorry! message to bob lee at bgsu
Date: 23 Jan 93 00:48:23 GMT
Reply-To: dhi00@juts.ccc.amdahl.com (mofo )
Distribution: usa
Organization: Amdahl Corporation, Sunnyvale CA

sorry to make this a broadcast message;

i need bob lee from bgsu to give me a useable email address to 
respond to.  mail me at the above address; i have a response for
you.

thanx

d
From: garland@ohstpy.mps.ohio-state.edu
Newsgroups: sci.electronics
Subject: Re: Power Amplifiers
Date: 21 Jan 93 06:04:38 EST
Organization: The Ohio State University, Department of Physics

In article <1jkrndINNrht@usenet.INS.CWRU.Edu>, ah335@cleveland.Freenet.Edu (Richard Banks) writes:
> In a previous article, schaefer@sal-sun93.usc.edu (Peter Schaefer) says:
> 
>>
>>Could anyone out there please give any recommendations on books or other such
>>literature regarding large-scale power amplifier design? Thanx in advance.
>>					Peter Schaefer
>>
> 
> I am looking for books on this subject as well, please follow-up to the
> group.
> 
> Thank you.

How about defining your needs a bit more precisely? Do you want 1MW high
frequency rf designs, 10kW rf induction furnance designs, ultrasonic amplifier
designs for medical uses, 1kW audio amplifiers for rock concerts, UHF
television 300kW designs? Or are you interested in motor controller amplifiers,
wideband pulse amplifiers for radar applications? Do you need amplifiers with
50ohm input/outputs? Voltage sources? Current sources? Give us some guidance
and maybe we'll all be able to offer suggestions.

Jim
From: claude@bauv.unibw-muenchen.de (Claude Frantz)
Newsgroups: sci.electronics
Subject: Re: Voltage drop across 1N4148 diode?
Date: 28 Jan 93 06:46:22 GMT
Organization: University of the armed forces, Munich
NNTP-Posting-Host: bauv106.bauv.unibw-muenchen.de

szopinsk@picard.med.ge.com (Jerry Szopinski Mfg 4-6983) writes:

>The voltage drop across the 1N4148 diode depends on what type of
>semiconductor material it is made of.  

According to the data sheet, it is allways made of silicon.

>If the diode is made of
>germanium (no, not the flowers) the drop is around 0.7V; if it
>is made of silicon then the drop is around 0.5V.

The voltage drop across a Ge diode is about 0.2 V, across a Si
diode about 0.65 V, depending on the current, the temperature and
the exact structure.

>The 1N4148 is usually used in computer applications and most
>general purpose circuit board applications where small currents
>are used.  I agree that the 1N4001 would be a better diode for
>this particular application.

The 1N4148 is a high speed diode intended for switching applications,
the 1N4001 is intended for rectifier circuits at low frequencies.

Regards,

Claude
Newsgroups: sci.electronics
From: byron@cc.gatech.edu (Byron A Jeff)
Subject: Re: Help Wanted: Sound detecting circuit
Reply-To: byron@cc.gatech.edu (Byron A Jeff)
Organization: Georgia Institute of Technology
Date: Tue, 26 Jan 1993 12:58:06 GMT

In article <1993Jan25.183720.12910@tellab5.tellabs.com> chrz@tellabs.com (Peter Chrzanowski) writes:
>In article <1993Jan20.104438.5447@ucc.su.OZ.AU>, andy@extro.ucc.su.OZ.AU (Andrew Miehs) writes:
>> G'day,
>> 
>> I'm not much in the know about electronics (but I'm learning) and so I'd 
>> appreciate anybody's help in designing the following:
>> 
>> I need a circuit that reacts to a certain high-frequency sound, in order to
>> activiate another circuit. Is that clear? In other words, when a microphone
>> picks up the sound wave from a nearby source, it turns some auxilary circuit
>> on and it stays on until the sound wave ceases.
>> 
>> Please e-mail me with any suggestions or references.
>
>Look at the schematic (Howard Sams, etc.) of a TV made sometime before the
>late '70s.  Old TVs used remote controls that used unmodulated ultrasonics:
>just provide enough energy at the right frequency and the function would
>be triggered.
>

I think we've moved a bit further since then. How's about using a 567 tone
decoder. It's an 8 pin DIP that uses an RC circuit to set the center
frequency and has a sharp bandpass filter around that freqency. It'll
even give you the modulated output without the carrier frequency if you
wanted to do some futher processing. Cost about $1 apiece at most electronic
supply places.

BAJ

>> 
>> Malcolm Ryan
>> 
>> (care of Andrew Miehs - email andy@extro.ucc.su.OZ.AU)
>> 
>> -- 
>> +-------------------------------+---------------------------------------------+
>> | Andrew Miehs                  |                                             |
>> | Mail: andy@extro.ucc.su.oz.au |       $$$ THIS SPACE FOR RENT $$$           |
>> | NB:   Don't call me andy!     |                                             |
>
>


---
Another random extraction from the mental bit stream of...
Byron A. Jeff - PhD student operating in parallel!
Georgia Tech, Atlanta GA 30332   Internet: byron@cc.gatech.edu
From: smithr@teecs.UUCP (Robert Smith)
Date: Tue, 26 Jan 1993 18:50:20 GMT
Subject: Re: making 110V into 220v
Organization: Litton Systems, Toronto ONT
Newsgroups: sci.electronics

One Major difference is that Euro power is also 50Hz. If the equipment
is not frequency sensitive then usually it will operate on 220V 60Hz.
but dont forget that inductive items will not have the reactance they
were designed for.

Bob.
. 
PS The electrical code also specifies receptavcles for 220V; if you ain't
   legal, you ain't insured.
From: troyz@microsoft.com (Troy Zerr)
Subject: Re: Power Supply Question
Date: 27 Jan 93 02:25:42 GMT
Organization: Microsoft Corporation
Summary: Look at "Best of Ciarcia"

In article <C1AH65.KGp@acsu.buffalo.edu>, v064mcqs@ubvmsb.cc.buffalo.edu (NEIL GANDLER) writes:
> 
>     Im designing a small power supply. I would like to know if using a 12v
> center tap transformer when full wave rectified and smoothed be more than
> 15 volts to allow a 12 volt regulator 7812 work properly. From my understanding
> the 78 series regulators need a 3 volt difference atleast. 
> 
> 		Neil Gandler

"The Best of Ciarcia's Circuit Cellar" has an article on designing
linear power supplies.  I highly recommend it.  Available at your local
nerd bookstore.

-- Troy
From: flux@sys6626.bison.mb.ca (John Kamchen)
Newsgroups: sci.electronics
Subject: Counter
Date: 27 Jan 93 07:07:13 GMT
Organization: System 6626 BBS, Winnipeg Manitoba Canada

I'm using a great chip from Avesem, a Video Genlock PLL chip, and I need
to design a counter that counts to 1818, then resets back to zero (with 
some kinda \RCO when it hits 1818).
I've looked through all my TTL data books, and nothing really strikes me
as being 'right' for this application.
The input clock pulse is 28mhz, so that rules out CMOS parts.
Any ideas?  I've got two kick-ass projects I can use this chip in, and
I can't do anything untill I figure out a counter.
 
-John
SSE BBS (204)589-1078 v32bis AmiTronics- MEGS of 'em
Newsgroups: sci.electronics
From: gsulliva@enuxha.eas.asu.edu (Glenn A Sullivan)
Subject: Re: What is the limit of a MODEM?
Summary: What said about bit rate lmits thru a channel
Keywords: Tools of AI.
Organization: Arizona State University
Date: Thu, 28 Jan 1993 02:30:29 GMT

lo@pi.uleth.ca (Zachary Lo) writes:..........
> I wonder any of you can send information about the transmit speed limit
> of a electronic modem which is used in a computer.

Claude Shannon first showed that relay logic could implement Boolean logic
operations. This was important since we thus were assured that anything
mathematics indicated was computable, was computable by physical objects.
(They may make me retake my CS PhD quals after that statement!)

He also invented information theory. As part of that, we can compute the
maximum bit-rate for a limited-bandwidth channel with finite signal/noise
ratio. (Note the MAXIMUM, LIMITED, FINITE)

MAximum bit-rate = 2 * (channel bandwidth) * LOGbase2(1 +SNR)

So if the noise power is 127th of the signal power, and the channel bandwidth
is 3000 cycles/sec [I used to own an RCA #80 vacuum tube], we compute the
bit-rate limit as
	2 * 3000 * log2(1 + 128)  = 6000 * 7 = 42,000 bits per second.

Sounds kind of high.

Probably just (channel bandwidth) * LOGbase2(1 + SNR)

Allen SUllivan
From: bote@access.digex.com (John Boteler)
Newsgroups: sci.electronics
Subject: Re: Recording from/playing onto phone line
Date: 28 Jan 1993 18:42:55 -0500
Organization: Express Access Public Access UNIX, Greenbelt, Maryland USA
NNTP-Posting-Host: access.digex.com

Mike Diack <mike-d@staff.tc.umn.edu> writes:
>Bill Jaeger, jaegerwl@wckn.dorm.clarkson.edu writes:
>>At my university's cable TV station we're working on putting together
>>a program that involves a viewer call-in.  
>>
>What you need here is a Hybrid. 
>This consists of a pair of transformers
>each having a single primary and a split secondary, cross wired to

>PS you may need a resistor to hold the phone "off hook" depends on
>your setup.

Good suggestions. Also, keep in mind that you want to block
the phone line's DC from flowing in the core of the transformers
with capacitors; that would lead to saturation distortion and 
make the sound worse than it has to be.

Experiment with values between 0.05uF and 1.0uF. Depending on
your setup, you might want to minimize the amount of low
frequencies you pull off the phone line so that you don't
drive your limiter crazy and end up with cruddy sound and
pumping of the compressor, if you use one. For an otherwise
high-grade outfit, C-SPAN's phone line audio is awful, for example. 
It can be done right.

For a holding bridge to keep the phone line busy (off-hook)
you can use something as simple as a 1K-1.5K resistor, depending
on your distance from the central office. Farther distance =
greater wire resistance = less holding resistance.

If you want to get really fancy, you can design a solid-state
current sink, but that sounds a lot fancier than what you want.


-- 
bote@access.digex.com (John Boteler) 
This week's usenet malapropism: foo, foo-foo
foo=general meaningless expletive, not deleted
foo-foo=the kind of sweet drinks they serve at Armand Chicago Pizzaria
Newsgroups: sci.electronics
From: kennehra@craft.camp.clarkson.edu (Rich"TheMan"Kennehan)
Subject: How to address RAM chips?
Organization: Clarkson University
Date: Thu, 28 Jan 1993 00:34:52 GMT



Hi.  I'd like to design a simple circuit using a small RAM chip that
will allow me to store a few bytes and allow me to read them back
again.  For example, I would like enter in bytes A4,3D,FF,22,4E and
be able to read back the third one without disturbing the others.

The main reason for this is so I can learn digital electronics.  Sure
I can read some books, but I need a hands-on project to really make
me remember what I read.  Thanks in advance!

- Rich
  kennehra@logic.camp.clarkson.edu
From: jpope@pafosu1.hq.af.mil (John C Pope)
Newsgroups: sci.electronics
Subject: UNIDEN BEARCAT Scanner
Date: 18 Jan 93 02:22:37 GMT
X-Newsreader: TIN [version 1.1 PL8]


  Hello people of the sci.electronics arena.  I am hoping one of you can
give me recommendations concerning the UNIDEN BEARCAT Scanner.  I don't know much about scanners but they look interesting.  The model I am looking at 
apparently requires only the state abbreviation and will scan police
channels and can get whether from NOAA.  Do all scanners do this?  What is
normally expected of a good scanner?
     The ad says that the UNIDEN BEARCAT scanner uses SUPER TURBOSCAN
technology! (is this good?)  It costs $75.  Is this a good price?  After all,
it has SUPER TURBOSCAN technology.  What would you recommend in the form of
a scanner?
     Since I have already admitted to not knowing much about scanners, I am
now free to ask really stupid questions like:

  1.  Won't CB's pick up the same frequencies?
  2.  What's the deal with separate antennae, won't a car antennae work
well enough?
  3. What's a good place to mount an antennae?
  4. What is a "telescopic" antennae?

I greatly appreciate any responses.  Please E-mail as bandwidth is not
recyclable.



    __/__/__/ __/            __/__/__/ __/__/__/
   __/       __/__/         __/   __/    __/   
  __/       __/__/__/      __/__/__/    __/   
 __/       __/      __/   __/          __/   
__/__/__/ __/         __/__/          __/   __/

    __/__/__/  __/__/__/  __/__/__/  __/__/__/                              
   __/   __/  __/   __/  __/   __/  __/        
  __/__/__/  __/   __/  __/__/__/  __/__/     
 __/        __/   __/  __/        __/        
__/        __/__/__/  __/        __/__/__/

John C. Pope,
Air Force Captain trapped in the Pentagon.
(703) 695-9415
pope@execpo6.hq.af.mil
From: cstadbg@csv.warwick.ac.uk (Mr M J Brown)
Newsgroups: sci.electronics
Subject: Re: Heat gun pcb cannabalization
Date: 26 Jan 1993 16:18:41 -0000
Organization: Computing Services, University of Warwick, UK
NNTP-Posting-Host: lily.csv.warwick.ac.uk
Keywords: Heat gun, charring, lack_of_skill, try_again_maybe


In article <C1EuMK.49w@sci.kun.nl> pieterh@sci.kun.nl (Peter Herweijer) writes:
>
>Using the very same method, I have successfully stripped a bunch of
>computer boards of their components, including Z80 CPU's and 8255 PIO's.
>Everything worked fine.  I did it with a friend, he heated the PCB, I
>pulled out the components and immediately threw them in a bucket of
>water to cool them off, but I don't know if that's necessary.  One tip
>though: do it outside.  The fumes stink and are probably not healthy.

I think the bucket of water would cool them down too quickly, this could
cause mechanical stresses. I leave them in a cardboard box lid on the bench


Definitely do it outdoors, or in a workshop near the door, wide open.
=============================================================================
     _/      _/   _/   _/  _/   _/_/_/_/   |
    _/_/  _/_/   _/   _/_/     _/          |         Michael Brown
   _/  _/  _/   _/   _/       _/_/         |
  _/      _/   _/   _/_/     _/            |   cstadbg@csv.warwick.ac.uk
 _/      _/   _/   _/  _/   _/_/_/_/  _/   |     mjb@dcs.warwick.ac.uk
                                           |    csulo@csv.warwick.ac.uk
=============================================================================
Newsgroups: sci.electronics
From: toddi@mav.com (Todd Inch)
Subject: Re: caller id block
Organization: Maverick International Inc.
Date: Mon, 25 Jan 93 20:38:45 GMT

In article <betel.727244356@camelot> betel@camelot.bradley.edu (Robert Crawford) writes:

>	A more interesting (to me) question: How could someone _with_
>caller ID screen calls that do not include the information? My idea is
>for the "black box" to sit between an answering machine and the
>telephone, and to not pass the ring signal unless the caller ID
>information comes along...

Great - if you don't want to receive any long-distance calls.  Calls
from other exchanges, especially in distant places, may not contain the
CID info because the necessary SS-7 protocal has not be implemented
everywhere yet.

Now if you can distinguish between "blocked" and "not available", that
would work fine.  This is probably dependant upon your hardware, but
may also be dependant upon how your local telco has things set up -
they may send one message for both conditions (although hopefully not!)
From: garland@ohstpy.mps.ohio-state.edu
Newsgroups: sci.electronics
Subject: Re: How do I create a 2A load to test a power supply?
Date: 25 Jan 93 08:48:45 EST
Distribution: na
Organization: The Ohio State University, Department of Physics

In article <o4RwXB1w165w@brewhau.bison.mb.ca>, magus@brewhau.bison.mb.ca (James Copland) writes:
> cs000rjp@selway.umt.edu (Russell J. Pagenkopf) writes:
> 
>> Hi! I have a sealed power supply that I need to test for voltage and
>> amperage under load and this is my problem, how do I create a 2 amp load?
>> The power supply uses 120VAC 0.40A grounded and outputs (supposedly) 20V,
>> 2.0A, 40VA Class 2  with four pins ( I have no idea what pins do what yet). I
>> understand that if I place my meter in series between the load and the
>> power supply, I should be able to read 20V (dc right?) and 2.0 amps. But
>> what does the 40va mean? 40VAC? I guess what this comes down to is, how
>> should I test this thing to make sure it is giving me what it should?
>>
>> Thanks for any help and sorry for wandering ;-).
>>
>> --
>>   Russ Pagenkopf                                cs000rjp@selway.umt.edu
>>  School of Journalism, University of Montana         cs__rjp@lewis.umt.edu
>> <There is no other wisdom, and no other hope for us but that we grow wise.>
> Salut!
> 
> Have you tried lamps in series and parallel for a load?  40VA means
> 40VoltAmps, just what you would expect from 20V * 2A.  If you place
> your meter in series with the load and source, you should measure
> Amps.  If your meter is parallel the load, you should measure Volts.
> All readings on the output should be DC (only a scope knows for sure
> 8-).
> 
> Regards,
> Magus.
> -- If I already posted this, file this one under _old timers_ disease. --
> --              magus@brewhau.bison.mb.ca (James Copland)              --

If you want a fixed load, buy a 10 ohm 50 Watt resistor; it will draw 2.0 Amps
at 20V, and dissipate 40Watts (or 40VA). If you want a variable load, the
easiest way to make one is to use a power transistor as a load, with a pot
controlling the bias current. I gather from your question, however, that you
haven't much electronics experience, so the resistor is probably the easiest
solution.