[EAS]Bypass Capacitors

pjk pjk at design.eng.yale.edu
Mon May 5 04:06:37 EDT 2003

Subject:   Bypass Capacitors

Dear Colleagues -

Apologies to my puzzled colleagues in other professions. In real
electronics, bypass capacitors are an essential ingredient that
compensates for inevitable non-ideal aspects of circuitry, perhaps
akin to lock-washers in Mechanical Engineering. I'm sure all
professions can name a similar essential ingredient, a metaphor for
distinguishing the inexperienced ideal from the functional reality.

Anyway, a few months ago I bought a used book online from Brad
Thompson, a bookseller in New Hampshire. Out of the confirmatory
email exchanges a conversation ensued. He had noticed my Yale
engineering connection, identified himself as a radio amateur and
contributing editor of an electronics industry magazine, and asked
about the exposure our undergraduate have to practical details: "I
hear comments from older EEs that new grads may be great at digital
circuit design but forget to include bypass capacitors."

That reference is as instant a sign of mutual recognition among
practicing EEs as a Masonic handshake, so we had further exchanges
on the need for engineering education to include such realities, as
indeed we do at Yale in our EENG 227a/229b introductory lab sequence.

Subsequently Brad quoted me (with my permission) in his recent
editorial for "Test & Measurement World"s May 2003 issue.


[If you are reading this not in your email, but in the EAS-INFO list
archives, then _every_ equal sign in the above URL has a spurious
"3D" after it. These you must edit out to make the URL work. If all
else fails, you can go to <http://www.tmworld.com> and then to the
"Archives", to the "May 2003" issue, and then scroll all the way
down to the "Viewpoint" Department.]

I also append below a list of insights Brad sent me in one of his
emails. One wishes these had much wider recognition than among those
of us who have had to earn them, often painfully.

All best,  --PJK

|  Peter J. Kindlmann     |  Prof.(Adjunct), Director of Undergrad.  |
|  Dept. of Elect. Engrg. |  Studies and the Morse Teaching Center   |
|  Yale University        |  tel.(203)432-4294, fax (203)458-3803    |
|  New Haven, CT 06520    |  email: pjk at design.eng.yale.edu          |
|        http://www.eng.yale.edu/EE-Labs/morse/about/pjk.html        |
0.) When something isn't working, the first item to check is its
power supply.

1.) We're awash in a sea of cheap computers and consumer
electronics, so never hesitate to take apart something that's
broken. Study its innards as you go, and ask yourself how and why
the designers built the gizmo as they did. Look up component 
numbers as you go, and study their data sheets. If you can figure
out what failed, try to figure out WHY it failed. Develop your
sense of curiosity!

2.) Go outside your textbooks and look for information elsewhere.
Subscribe to several controlled-circulation magazines (or look in
the college library) -- even if you have to invent your own company
to qualify for a free subscription.  Don't rely solely on the
Internet as your source of information -- it's only a few  years
old, and people published all kinds of good and interesting work
that you'll never  find on the Internet.

3.) Learn the history of your profession. if you don't understand
the past, certain aspects of the present will seem mystifying or

4.) As you go, assemble your own personal database and library.
Collect books, snip and save magazine articles, download information
from the Internet-- and organize you collection so that you can
easily find what you save.

5.) Instruments can lie. For example, an analog oscilloscope is
sometimes  more truthful than a digital scope-- and vice versa.
Learn when to trust-- or distrust--  measurements.

6.) When you receive your first paycheck, IMMEDIATELY begin stashing
money in a go-to-hell fund. Given the cyclical nature of the
electronics industry,  you need reserve funds to carry you (and your
family) through a layoff-- or when you  can no longer put up with an
employer's abuse and overwork. Don't dip into your GTH fund  for
everyday purchases, and be conservative in your lifestyle and
expenditures. Let the  jocks and B.A.s go into credit-card overload
and perpetual debt. You don't have to live the  life advertisers

7.) Be a mentor-- pass along what you learn even though it's
unfashionable to do so. You'll feel better when you help a

8.) Look out for yourself. Lifetime employment with one company has
gone away, and you'll probably change jobs several times. Learn all
you can at your present  position, and don't be afraid to stretch
yourself into a new job that's not exactly in your specialty.

9.) Never stop learning-- and remember that most learning occurs
outside  the classroom. Experience is directly proportional to
mistakes made and equipment ruined.

10.) Connector (n): a source of trouble that joins two other sources
of  trouble.

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