Lecture Text
How much circuit theory is
required to troubleshoot a circuit?
You may have noticed
that I have not spent much time on phasor analysis and none on complex
numbers. If you didn't learn about imaginary numbers and logarithms in high school,
I would have to spend a lot of time teaching mathematics. This would force
me to deviate from the primary objective of this course which is to teach fault
isolation and not design engineering.
The second reason
that I am deviating from the standard electronics course curriculum is
that technology has changed in the last thirty years. Allow me to
explain. When, I first started troubleshooting, circuits consisted of
transistors, diodes, and passive components. Passive components being
resistors, capacitors, coils and transformers. It was relatively easy to
probe any component of the circuit assembly, and isolate the fault
to a component. I once worked on bench testing transistor circuits that were
smaller than a cubic inch. I would isolate faults to a resistor,
transistor, or a capacitor. After passing test the units were
encapsulated. Each of these units was a single operational amplifier
to be used in avionics equipment. Today you can get four operational
amplifiers on a piece of silicon the size of a match head. This tiny chip is
than mounted onto a single 16 pin inline capsule. The
point is that technology has changed. The job of operational amplifier
tester and repairman has disappeared. In 1970 I did 90% of my
troubleshooting by hand with meters and oscilloscope, and 10% by
computer controlled automatic test stations . In 1998 90% of my troubleshooting
was done by analyzing data on a screen or examining a computer printer paper dump.
I hope my site is
found helpful to students who to do not have the availability of technical schools, or public libraries. It may seem strange to think that there are students without
access to books, but have Internet access. There is an
international effort being made to provide computers to remote village schools
in developing countries. I know this from watching educational TV channels
like PBS, History, Discovery and others. The Internet can provide as much
information as a million dollar neighborhood public library. Of course
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