M P wrote:
> One can find all that in the academic texts but they take two hundred
> pages to start explaining it. If someone explained that to me in a
> popular language in my early days, I would have enjoyed my university
> time much more. And if all theories were explained in such a way, it
> would take approximately one book for the whole four year course. So,
> Ivan get to work.
I'll take that as a complement. Thank you!
There's just one problem: I am not a professor! All I did was show up for
class, pay attention, and study hard (well, most of the time). Doing that,
I managed a B in Fields I and an A in Fields II. Not being a tenured prof,
any book I would write would not have standing in academia. And if it was
too good and too easy to understand, it would reduce the number of courses
and semesters needed for the EE degree! Tuition revenues would plummet,
and there would be staff cuts! Textbook sales would decrease! The need
for new construction of classrooms and expansion of facilities would
disappear! Now do you understand the evils of increased efficiency? ;-)
There is lots of math that is needed to back up the field theory. What I
wrote yesterday had no math proofs of the field theory. So, in effect,
what I wrote was unsubstantiated. However, in order to offer proof, I
would have to get into the math. While the math is essential for a
complete understanding of fields, it is way beyond what is needed for a
"working knowledge" of fields. And the math does not help explain field
theory to someone whose math skills are less than expert. IMO, the problem
with EE textbooks is that they rely entirely on math to explain the theory.
Even among people who understand the math, page after page of equations
tends to blur one's vision. What is needed is a multi-faceted teaching
method: 1) explain the subject in plain language as much as possible, 2)
give examples or draw analogies in plain language, 3) present the math
proof, 4) explain how each step of the math proof actually proves
something, and 5) give worked out examples using the math proofs. I have
yet to encounter an EE textbook that does all these steps.
Oh, those profs! How clueless they were, about real circuitry! My prof
for Fields I (also my faculty adviser) was a total theoryhead. Every time
a discussion came down to prototyping a circuit, he insisted that was too
simple a subject for him to waste his time on. He didn't even approve of
his undergraduates fussing with actual circuits. A waste of an engineer's
time, he thought - leave that to the technicians. It was all I could do to
supress my anger when he exhibited that attitude. Meanwhile, I would hang
out in the lab, helping other students struggle with the proper pinout of
TO-92 and TO-220 transistors, hooking up the scopes properly, how to take
measurements, etc. There were 3 of us in the lab (all undergraduates) who
knew what we were doing, the rest of the students were clueless (especially
the honors students). We spent more time helping them than working on our
own projects. What made the difference for us 3 was that we were into
electronics as a hobby before we went to college for the EE degree. The
others had no previous exposure to electronics. I have no idea what made
them decide to go into EE...
Best regards,
Ivan Baggett
Bagotronix Inc.
website: www.bagotronix.com
M P wrote:
One can find all that in the academic texts but they take two hundred
pages to start explaining it. If someone explained that to me in a
popular language in my early days, I would have enjoyed my university
time much more. And if all theories were explained in such a way, it
would take approximately one book for the whole four year course. So,
Ivan get to work.
As for the vias, it mostly depends on the board manufacturers. Let's say
their minimum whole size is 15mils (realistic value) and their specified
minimum anular ring width is 8mils (again realistic value) that would
result in 15mil + (2 x 8mil) = 31mil. You can either stick to their
specs, or try to get down to 30mils and hope all goes well (not
recommended), or add 1mil to the annular ring (trust no pcb
manufacturer) and get 33mils overall diameter. 1mil means a lot on a pcb
and can be a difference between making the board or not. I haven't seen
any specific rules correlating the track width and the via diameter.
Igor
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