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"Kind Words"

To everyone who took the time to write and Comment on, and or make Suggestions on our WEB Page: "Thank You."

e-mailed --Kind Words | Guest Book --Kind Words | --Some Questions & Answers

From: "John Stoler" <>
To: <>
Subject: WWW page response
Date: Sun, 16 Nov 1997 10:53:

Glen,

Kudos on a fine (read: excellent) piece of web construction.
I have been around since the dino and have evaluated a book or two in my
days, but as far as teaching goes, I have not evolved nearly as far as yourself.
The electronics tutorial is not just well done, it is a credit as to what we should be looking for on the www.

I showed your page to my wife and tried to explain to her how this type of
work will eventually transend the garbage currently being force fed to the
populace (down with Lotus!!!)

Good luck with your web authoring and best of luck.

John Stoler

ARS: NF7W

Date: Sat, 27 Dec 1997 05:56:
To:
From: Robert Shields <>
Subject: Love your ECE 480 Site!

Hello Dr. Williamson,

My name is Robert Shields and I am writing to encourage you to keep up
the good work. I am a recent Electrical Engineering graduate of Virginia
Tech in Blacksburg, VA and happened to come across your wonderful site
(http://www3.ncsu.edu/ECE480/). The explanations and illustrations of
engineering concepts are superb! The site has so much "life" even without
background sound ... I spent so much time on the site that I had to write
and express my gratitude for such an enjoyable Internet experience.

Sincerely,

Robert Shields

From: "Dan" <>
To: <>
Subject: Love it!
Date: Mon, 11 May 1998 21:48:

Your web site is exactly what I have been looking for, for a long time now.
It is very explanatory without going into "way over my head" technical
lingo. I can finally understand what's going on. Thanks and keep up the
good work.

I will let you know if there is anything I would like to see that's not
there.

Thanks again
Dan Fleming

From: "Josh Logan" <>
To: <>
Subject: ECE 480
Date: Sat, 6 Jun 1998 06:45:

Your site is really great !!!!

Josh Logan N7XM in Colorado

Date: Thu, 04 Jun 1998 17:26:
From: "Brian P. Wilson" <>
To:
Subject: Wow!

My goodness! I came across your site when doing some research for a
presentation I have to give in my ENGR 333 class.

I will certainly be visiting your site again when I have more time. I'm
still a little awestruck at the quantity and quality of the material you
have to offer.

Brian

To:
Date: Mon, 01 Jun 1998 04:53:
From: "Robert A. Huber" <>
Subject: 555 timer

Glen,

I visited your website today and got a real boost in my web interest.

If possible, can you answer one question about the 555 for me?
I am trying to produce a delay circuit with the 555 and need the output NOT to change unless no input occurs for time longer than the output time.
In short I want the one-shot to be retriggerable.

Thank you, and best regards
Bob Huber KC8JUL

---

943 Cambridge
mason, ohio 45040

Date: Wed, 12 Nov 1997 14:01:
From: "Larry L. Ward" <>
Subject: web page
To:

Dear sir,
You've got a great! web page.........best I've seen yet.

Sincerely
Larry L. Ward
KSLU-FM
Southeastern Louisiana University
Hammond, La. 70402

From: Jim Kehler <>
To: "''" <>
Subject: Web Page
Date: Tue, 12 May 1998 13:57:

Hi Glen,
   I happend to find your web page, and I think it's one of the most
interesting ones I've seen. I'm a ham radio operator, but I'm not
an electronics engineer, and I find your pages very informative.
I'm at the point in my ham career (25+ years) where I finally have
some time to sit down and build a few simple things, and the basic
info you have about transistors, the 555 chip, etc., I find very
helpful.
   Right now I'm trying to design a sort of VOX circuit, not having
much luck, but having lots of fun and getting lots of solder on the
floor........
   I think I saw somewhere on you page that you metiioned you
were a ham also.

73, Jim KH2D
Mariana Islands DX Association - http://www.guam.net/pub/midxa/

Date: Wed, 10 Dec 1997 21:57:
From: Joseph Michael Hensley <>
To:
Subject: thanks

This page is really cool. I did my 480 project on Gilbert Cell
Modulator. Thanks for the neat stuff.

Mike

Date: Fri, 17 Apr 1998 14:55:
From: "E. Carranza" <>
To:
Subject: Your web page

I would like to congratulate you on such an amzing web page
that you are created.
I like all the animations, they simplify the learning process very much.
I hope that you keep this web page growing as it would be very sad
to see such good material disappear.
I am sure that this take a lot of your time to mantain, but you are
doing an excellent job.

Sincerely

Edgardo carranza
Power Supply Design Technologist
Toronto, Canada.

Date: Sat, 11 Apr 1998 20:35:25 EDT
To:

Subject: Re: 555 timer

Thanks that answered my question perfectly. I am using a 555 timer and some D flip flops for a computer engeering project and the drawing in the book was hard to understand. Thanks for all of your help

Ronnie

Date: Sun, 29 Mar 1998 15:27:22 EST
To:

Subject: Website

Mr. Williamson
I just finished viewing your website, very impressive. It has been difficult to find information on electronics on the web. Your website seems to cover many details on the subject. I am bookmarking your site for future visits.
Keep up the good work and please, please keep it free.
Thank You
Mark G

From: "Bill Thomas" <>
To: <>
Subject: Thank-you
Date: Sat, 28 Mar 1998 20:28:

Just a note to extend my thanks to you for a great site concerning 555.
Well done...

Sincerely,
Bill Thomas

Date: Sun, 05 Jul 1998 11:43:
From: Irvine Bernard Rogers <>
To:
Subject: A GREAT HOME PAGE

TO: Glen A. Williamson

- A GOOD HOME PAGE

I'M A RUSTY ELECTRONICS TECHIE FROM THE 60'S - AND WAS LOOKING FOR AN
OLD UJT TIMER CIRCUIT TO PULSE A 12 VOLT ALARM BUZZER (ie. 2 sec every
15 sec to conserve battery),

WHEN I FORTUNATELY STUMBLED ON YOUR TRANSISTOR PAGE - A FUN REFRESHER.

ALTHOUGH I COULD NOT FIND A UJT RELAXATION TIMER ON THE WEB, I DID FIND
YOUR PAGE IS A GOOD RESOURCE OF VALUE, WELL AND ENJOYABLY PRESENTED.

A FUN REFRESHER.

RESPECTFULLY, IRVINE B. ROGERS

Date: Thu, 25 Jun 1998 11:55:
From: "Andrew O'Malley" <>
Organization: Ryerson Polytechnic University
To:

Hello . . .

I needed the 555 data sheet, so I did a web search, and your site came
up first on the list, and I found everything I needed . . . Checked out
a bit more of your site, and found it all very well put together.

Definately excellent!
--

aNDREW o'mALLEY
                  ++ //
                  ++ //
                  ++ //
                  ++ //
||||||||||||||||++ //|||||||||||||||||
                  ++ //
                  ++ //
                  ++ //
                  ++ //

"If no one's laughing, you can bet they've been paid
not to find out what's going on."

From - Wed Jun 24 15:44:38 1998
From: "Norman, Russ" <>
To:
Subject: Your 555 Timer Web page!

Glen,
I am an engineering aide with Raytheon Systems Company and was having a
problem with a delay generator circuit one of our engineers had designed. Through a web search I found your site and I must say it was quite helpful. It turned out we had forgotten the differentiator on the input to both stages to the LM 556. Once installed it worked as advertised! Thanks for the wonderful site, you saved our project several hundred dollars!

Russ Norman,
Senior Engineering Aide,
Raytheon Systems Company

Date: Sun, 14 Jun 1998 22:17:
From: "Derek D. Bass" <>
To:
Subject: Laser Microphones

Mr. Williamson,

I've been reading various pages about Laser Microphones and their
practicality and portability, and I was wondering, given the variety of
Microphone schematics given on your site, what your personal findings
were as to the kind of fidelity you could expect with any of them. I'm
writing a fiction piece based upon 'Weird Science' (the genre, not the
movie), and I'd like to know what is possible in reality before I take
it a couple of steps further. Actually, I was hypothesizing about such a
device, and decided to look on the Internet to see if there was anyone
else working on the same idea. It was kinda nice to see this sort of
thing in a 400-level class in Electrical Engineering, since my own
schooling is in Psychology. I'm starting to ramble now, so I'll go. Any
response (excluding profanity and obscenity) would be most welcome, and
I thank you in advance for your time.

Sincerely,

Derek D. Bass

P.S. That's a nice site on Laser Microphones you've got there. That's
why I wrote you in the first place.

Date: Wed, 15 Apr 1998 15:59:
To:
From: "Renard A. Dellafave" <>
Subject: Hello from a recent alum

Glen,
I graduated Dec. 96 (BSEE,SCL) and have been working for a small
electronics firm ( http://www.4pi.com ) for almost a year now.

I found your ECE480 pages while looking for an online data sheet for the
NE555, seeing as how the ones here are probably a decade old. Interesting
trick with the AC coupled trigger, but tolerances will be tight if I try to
get 2.5uS pulses out of a chain of 555 monostables. Maybe too tight.

Anyway, I browsed on to your decoupling page, and had a suggestion/question
about the LC power filter arrangement you show on the amplifier cascade.
Would it not be better to use a "star" configuration where the high side of
each L is connected to the power supply?
The design as shown would provide a larger inductance for the sensitive
first amp, though, at lower cost than using five different value inductors.
As always with BDSG, there are many options, often with no clear one
standing out as superior - hence it getting the name "black magic" so often.

Well, anyway, while I don't miss the rest of college, I do miss the
informative lectures, and reading your webpages has shown me a few things,
reminded me of a few more, and if nothing else, made me think. Thanks for
having 'em.

RAD

Date: Tue, 24 Mar 1998 19:51:
To:
From: Jonathan Newman <>
Subject: suggestion for http://www3.ncsu.edu/ECE480/480_555.htm

great site. Very helpful. I think you should add some more uses for the
555 and include formulas.

newman

Date: Wed, 25 Mar 1998 00:00:
To: "Glen A. Williamson" <>
From: Jonathan Newman <>
Subject: Re: suggestion for http://www3.ncsu.edu/ECE480/480_555.htm

I wasn't expecting a reply so quickly. Could I trouble you just a bit?
I'm playing with using 2 555s to generate a PWM waveform, and I'm not
really getting anywhere. The first timer works fine generating a carrier.
The second isn't exactly modulating it too well. Let me know if this is
not your area of interest. Thanks again for the great site.

newman

From: "Fadi Awaida" <>
To: <>
Subject: Admire !
Date: Fri, 6 Mar 1998 16:15:07 +0200

Dear Mr. Williamson,

I heared of your internet page from a friend of mine in San Fransisce and
I checked it. Simply, it was my dream page - just what I needed!!!
I am a computer engineering student and i'm about to graduate this year,
God willing. I thought you might help me since i am a part of an important
project which is to build an FM Radio station for the whole University!!!
It is a big project that has many parts and many persons working in it.

The group that is working on that project is a respectable group in my
university and is known as the "Engineering Society" and is funded by the

university. It's members are computer and electrical engineers.
Your assistance will be reported to our dean and will show on our papers
and project.

So, please, help us in finding the right schematics and diagrams.
Also, I want to know if you do "sell" the circuit parts (all kinds of
resistors, capacitors, transistors, op amps,.....etc).

I'll be waiting your answer on that so please take us into concideration.
And if you feel you don't have time for that please feel comfortable to
say it "quickly" because we are limited in time.

Thank you, sir.

Regards,
adi w. awada

Date: Fri, 09 Jan 1998 16:28:
From: Christopher Bruno <>
To:
Subject: Suggestion

Hello Glen,

Your web page is fantastic. I'm an ME with a Master's
from Worcester Polytechnic Institute and I think your
electronics information is most valuble. However, I
think there is an error on your page.
On 480_base.html I think you will find that
one of the equations in the Ohm's law table is
incorrect. That is, the one that say P=I^2/R
should read P=I^2 * R.

Just trying to help!

--
Christopher Bruno
Teradyne
321 Harrison Ave. MS/H63
Boston, MA 02118
Office
Fax

Guest Book --Kind Words

Date: 02/13/98 13:56:59
Name: Robert Bowles
E-mail:
Homepage URL: eielson.af.mil

Opinion of site: Very Good

Comments:
A very good resource for information on electronic principles.....
I hope you can continue to maintain this site as well as expand it....

Date: 02/26/98 07:24:14
Name: Brian Hammill
E-mail:
Homepage URL: www.ipass.net/~hammill

Opinion of site: Very Good

Date: 02/27/98 16:59:43
Name: Victor Jacobs
E-mail:
Opinion of site: Very Good

Comments:
I wanted to say this website is great. It is very educational and usefull.
I am currently working very hard to transfer to the Computer Engineering Dept. at NC State.
I have read about the excellent methods in which the department teaches its students, and I can't wait to attend the University.

Date: 03/21/98 03:26:19
Name: Rainer Ekstrand
E-mail:

Opinion of site: Very Good

Date: 03/24/98 20:30:51
Name: Jonathan Newman
E-mail:

Opinion of site: Very Good

Comments:
Great site.
My whole Junior EE class at Tulane uses your site to remind us of all the things we could have learned in circuits and electronics.

Date: 04/15/98 15:14:35
Name: Renard A. DellaFave
E-mail:
Homepage URL: <none>

Opinion of site: Very Good

Comments:
sent separately in email

Date: 05/14/98 12:40:00
Name: Michael J. Benns
E-mail: chemdiff
Homepage URL: na

Opinion of site: No answer

Comments:
How did you get a piicture of my home phone for "Net Tips" After 20 minutes, this site made "Favorite Places"
Have not seen all, plans are to do so Further thoughts will be forthcoming

Date: 05/14/98 12:57:41
E-mail: chemdiff
Opinion of site: No answer

Comments:
Pretty dad gum neat!!! (I will get tto communication, personal later) And a better keyboard.

Date: 06/09/98 15:31:56
Name: Sterling C Nicholson
E-mail:

Opinion of site: Very Good

Comments:
This site was recommended by our Electronics Division supervisor to bookmark for reference.
I found it very interesting. good job !!

Date: 06/15/98 10:10:06
Name: Jason MCcue
E-mail:
Homepage URL:

Opinion of site: Very Good

Comments:
Good source of info!

Date: 06/23/98 13:01:29
Name: Alan de Schweinitz
E-mail:
Homepage URL: www.digitan.com

Opinion of site: Perfect

Comments:
I am a practicing engineer with 30 years experience.
This is an excellent use of the internet with a great amount of useful information for anyone at any career level.
Keep up the good work!
I was looking for a way to search your site by content--lots of good stuff plus the pictures make it outstanding.

Date: 06/29/98 12:04:16
Name: Thomas C. Sefranek
E-mail:
Homepage URL: http://hamradio.cmcorp.com/

Opinion of site: Very Good

Comments:
Congratulations!
This is probably the best site I've seen for explaining the basics!
I teach, and I appreciate the time and effort!I'll be sending my students to this site!
Truly a great site!

Tom

Some Questions & Answers

Date: Mon, 08 Dec 1997 17:47:00 +0000
Subject: NTSC info
To: ('Glen A Williamson')

Hi there. An employee of mine visited your website and picked up your paper
on RS-170 standards. It should prove to be very helpful in educating some of my test technicians ( and myself for that matter.)
I have a question on the color burst portion of the signal that I have not
found the answer to in my travels. Is there a requirement for this signal to
remain phase locked to the RS-170 signal on which it rides? In other words, if I were to look at a standard RS-170 signal on an oscilloscope, would the
color burst portion of the waveform remain stationary, or would it appear to be in motion?
We build a product that encodes RGBS video into NTSC. The local color burst
oscillator in this product is not phase locked to each line of the output
signal, although it does,of course, maintain a given phase relationship to
the chroma portion of the signal. I have found that some of our test
monitors display some artifacts that appear to be related to the beat
frequency of the color burst in relation to the RS-170 signal. I noticed
that our test generators signal is phase locked, but this is due to the fact that their color burst oscillator drives the counter that generates the RGB
outputs. I have not gone through the bother of phase locking tha local
oscillator since I didn't know if it would help the circuit performance. Any
insight you could provide would be greatly appreciated.

Joe Fischer : fsr! p> <hr SIZE=4 WIDTH="90%"> Date: Sat, 02 May 1998 17:48:54 +0200  From: (Zanotti Robert)  To:   Subject: Adjusting reduced-carrier ssb    Greetings from Switzerland.  I am responsible for engineering at a volunteer cultural SW station in Milan, Italy.  We have opted for -6 dB reduced-carrier SSB for efficiency reasons (according to ITU recommendations). The xmtr is a 1972-vintage Siemens communications type, very robust and reliable, rated at 10 kW PEP (A3J). We are running considerable less in A3A mode to conserve the very expensive final.  My problem is properly adjusting the carrier-to-PEP ratio for the  nominal 50% carrier reduction (-6dB), while maintaining acceptable  on-air sound quality. I assume that if, for example, we are running 1 kW  carrier output, we would also adjust the SSB modulation (using a tone)  for an output of 1 kw (assuming a 1.6 to 2.0:1 increase in the case of  complex modulation, for up to 2 kW PEP).  Does the seem correct to you? I am asking because in practice, we always  seem to be have unacceptable distortion in ordinary DSB receivers. This  may, in fact, also be partly due to heavy modulation processing (Orban  9105 clipper). Perhaps in the real world, less reduction (e.g. 4 dB)  might be more in order. Your comments much appreciated.  Many thanks and best 73,  Bob Zanotti HB9ASQ  ---------------------- Response -------------------  From:  Glen A. Williamson[SMTP:]  Sent:  04 May 1998 06:33  To:  Zanotti Robert Subject:  Re: Adjusting reduced-carrier ssb  Bob,  Your question is one that sent me scurrying to some of my very old books.  There has been a lot of work done with CSSB, A.K.A., SSB-EV over the years.  Unfortunately, none done by ME!  Your suggestion of not reducing the carrier power by as much as half (-3dBm) seems a place to start.  However, one of the several problems with this mode of emission: your signal is at the mercy of the quality of the average double sideband--AM--receiver (envelop detection).  Another is how the average person might tune their radio, i.e., the carrier and USB position within the IF bandpass. Something as simple as that could negate a perfectly tuned transmitter.  I will offer several thoughts, BUT they are just that!  I am by no means (spelled NOT) the definitive source on this.  1) A source of transmitter distortion can be: if there is any vestigial sideband, the receiver's envelop detector will add the power of both common spectra. A simple solution might be to weight the audio at those frequencies for normalize receiver response.  A drawback to this approach is anyone receiving your signal using (synchronous) product detection will not hear those frequencies faithfully.  2) I am assuming your transmitter PA is operating in AB-2 mode and that you have selected the tube manufacture's recommended static grid bias for this particular service--CSSB.  However, this shouldn't cause audible distortion unless it is severe (IM products); normally it causes harmonics.  3) It would be instructive if you could arrange for a typical AM receiver to be placed at some distance from the transmitter (Far Field--a mile or more) that could be monitored remotely (Video camera looking at an oscilloscope and/or distortion meter via the Internet or ATV). This would be ideal for trying various Carrier to Sideband ratios, using Single-Tone, and Multi-Tone testing.  Anyway, these are some thoughts--I wish I could help more.    Take care Bob,  --73s          glen   K4QNL, x/KX6AY  ---------------------- Response -------------------  From: (Zanotti Robert)  To: "'Glen A. Williamson'" <>  Cc: "'alfredo'" <>  Subject: RE: Adjusting reduced-carrier ssb  Date: Mon, 4 May 1998 11:57:44 +0200    Thanks very much for the tips and other comments, Glen. It was good to  get confirmation of my own suspicions and practical experience. I think  the ITU -6 dB figure is theoretical and does not take into account major  factors like EQ and other modern processing techniques. In our  experience, a carrier reduction of -3 to -4 dB has proved the most  acceptable, using AM receivers as the standard.  The transmitter is "forgiving" and well designed for this mode. I believe  the PA is OK. As an economy measure, we ARE running the grid bias a  little "cool", although this was recommended by the engineers who  operated the transmitter before. We haven't noticed any serious disadvantage.  You're absolutely right about the disadvantages of A3A modulation when  received by a conventional AM detector. We weighed up the pluses and  minuses and concluded that since there are so many SSB receivers in use  in the target area, the advantage of SSB outweighed the disadvantages,  especially in DX areas. Personally, I still prefer the "sound" of AM  (at least for BC work).  I'll let you know what happens. Thanks again in the meantime.  Bob Zanotti  HB9ASQ </font

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