Hi BradtheRad,
I appreciate your desire to simplify things in order to facilitate the understanding of operation principles for parts, which are slightly more complex than a resistor.
However, it`s a critical path and there is always a danger to oversimplify things.
According to my experience, it is of great importance for beginners to learn that voltage-current relationships in electronic circuits - in particular, if they contain semiconductors - are non-linear.
That means - not all parts behave according to Ohms law. This is very important to realize - and this is my key argument against a "mental construct" like "A transistor will assume 5 ohms internal resistance when biased so it delivers 1 A.
I am afraid, such a thinking can (will) lead a novice into a false direction.
More than that, as a by-product one can learn about the characteristic properties of linear and non-linear elements.
Example: Frequently, I have heard that capacitors and inductors are "non-linear" (because of frequency dependence)
Yes, and I recognize it's important to be grounded with a right understanding of the basics. I'm thinking about Feynman's story telling how appalled he was at seeing the inaccuracies in science textbooks which he reviewed.
As for transistor principles, every primer I've seen speaks of majority and minority carriers, emitter region, base region, etc. I suppose any other electronics student has seen the same.
I did not realize my post #6 was addressing the basics of transistor operation. After all my phrase was 'net effect'.
I acknowledge that my reference to a transistor acting as part of a voltage divider, would not appear in chapter 1 about transistor usage.
However such a discussion might appear in a later chapter.
May I provide these additional arguments as a follow-up to your argument?
1.
Chapter 2 (or 3 or 4, take your choice) tells about the basic configuration of transistor amplifiers. Common base, common emitter, common collector.
Charts compare each types parameters. Such as voltage gain, input impedance, output impedance.
I used to look at these specs, but I did not grasp where they came from. A transistor was supposed to be a current source. Such specs were obscure theory until I tried to devise model transistor behavior for my own homebrew simulator.
I had to calculate the transistor's internal resistance, after first figuring out the maximum current it could draw depending on bias current. I recognize that I must first evaluate it as a current source, secondly as a variable resistor.
2.
As a teacher you have just explained to a class about the operating principles of transistors. You are careful to point out that it is a controlled current source, not a variable resistor.
There is bound to be an alert student who will ask:
'Where is Ohm's law in this? Every day we hear how Ohm's law governs electrical behavior. How does the transistor comply with Ohm's low?'
The answer will have to be about the transistor changing its own internal resistance, in order to act as it does.
3.
Transistors and mosfets are known to overlap in their usage. Among the chief specs for mosfets is minimum-On resistance.
It's natural to extend that to transistors as well. Because when using either a transistor or mosfet to switch high current, its On-resistance becomes a prime concern.
4.
A retired electronics teacher showed me a quiz he used to give his students. It took a schematic of an ordinary transistor amplifier, and duplicated it several times. Each image had volt readings at nodes.
In each case the question was 'What fault in the transistor would cause these unworkable volt readings?'
To solve the questions, I had to picture how the transistor 'pulls the collector terminal low or high', or 'shows hi resistance to bias current', etc.
The troubleshooting process required that I imagine the transistor as having invisible resistors inside.