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Re: Transistorized

On Thu, 4 Nov 1999, Warren Hein wrote:

Transistorized! a PBS documentary about the invention of the transistor will
be nationally televised on PBS on Monday, November 8, 1999 at 10:00 PM ET.

There is a companion web site www.pbs.org/transistor which has a Teacher's
guide to accompany the documentary online.


Does everyone here feel that they have a solid grasp on the nature of the
bipolar transistor? As a student I always felt that I didn't REALLY
understand what was going on within them. I knew a lot of disjointed
facts, and I knew how they behaved in circuits, but I never was able to
assemble this into a coherent mental model. I even felt this way while
taking undergrad courses on the physics of semiconductors.

As you might suspect, I eventually discovered that something was standing
in my way: misconceptions. Here are two:

BIPOLAR TRANSISTORS AMPLIFY CURRENT. A TINY CURRENT IN THE "BASE"
LEAD CONTROLS A LARGE CURRENT IN THE "COLLECTOR" LEAD.

THE ELECTRONS AND HOLES WITHIN A SEMICONDUCTOR FLOW AT A CONSTANT,
VERY HIGH SPEED.

Textbooks clearly state that transistors amplify current. I never was
able to figure out how one current could control another. Today I see
that the whole idea is false. Bipolar transistors do not amplify current,
and if we believe that they do, this sends us down a dead-end path which
prevents further learning.

I'm wondering if any other PHYS-L subscribers have come to similar
conclusions? Was I just slower than most in grasping an obvious concept,
or do others have the same difficulty?

Someday I gotta learn JAVA, so I can write little animated-graphics apps
which let people see the inside of a BJT as the 'transisting' takes place.
The reality is very different than I was originally taught.


((((((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))))
William J. Beaty SCIENCE HOBBYIST website
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