MrAl,
Do you mean post #19 of this thread? Yes, I did. You did not specify whether you are trying to determine its functional or causal classification. Did you read my comments about a true current source not having little or no voltage across its input terminals? It doesn't matter much, however. By adding external circuitry, we can make a voltage source into a current source or vise versa. All I am saying is that at the quantum level, it is voltage that determines the charge flow.
Ratch
Knowledge of any kind is obtained by dividing subjects down more and more until we get at the root of the subject. It doesnt really help to divide it down and then suddenly throw it all back together again which only causes confusion.
We learn things about a device by learning more and more subdivisions of how it works. If we start to classify it with a more broad viewpoint we actually might end up saying less about it then we did before.
If we wanted to do that we would end up saying something like, "The transistor is an object", which only says that it is one of many objects in the universe and doesnt really boil down to much, does it? We have to start to say what kind of object it is and maybe how it is made and maybe how it works.
Case in point: the operation of the transistor; how it works. If we want to say that it is field controlled then so what, what does that buy us? Everything under the sun is field controlled so what good does that do? That doesnt tell us anything more about it in general than any other device, including a resistor. We can propose a theory of how the transistor works inside by mentioning how the electron shifts bands after the application of an electric field, but that's just quantum mechanics, and that happens in every device. We want some definitions that are going to help us to use the transistor in real life, and most of the people coming to this site will want that same thing. It might be ok to talk about it that way, but it should be held in proper context.
Question: Is the thermoelectric effect caused by heat or by movement of charge?
Answer: Heat initiates the movement of the charges but without the movement of charges we wouldnt have the thermoelectric effect.
If you want to say that a current source can not operate without an applied voltage to its input, that's ok, but then i can say that if you want to apply a voltage then you first have to separate charges.
What we say about the field causing the movement of charges will most likely be superseded by String Theory's vibrating strings anyway, so maybe i can say that it's not the field really it's the vibration of tiny strings. Do we then say that the transistor is "string controlled"?
Take two small metal balls and hold them together tightly and apply a voltage across the two. The two balls in contact create a short circuit which has zero capacitance. Move them even a tiny fraction of a millimeter apart and now we have capacitance to overcome if we wish to energize the two balls, and to do that we have to move charge where there was no charge previously, and that means once we apply the electric field it will initially short out and become zero volts until that capacitance is satisfied. Thus, any device that has two terminals that do not make a short circuit will have input capacitance. It's true that there is inductance too in series with the voltage source so the voltage source itself does not go to zero, but the two balls potential, even though we just applied an electric field, will go to zero before any current flows and as the voltage increases so does the current. So if we want to say that there is a theory that inside the transistor fields are making everything happen, we are taking a very limited viewpoint where we set things up the way we want to before we start analyzing anything. To really understand we have to let the transistor be as natural as possible, and when we do limit things we are going to allow in the discussion we have to make it clear that that is what we are doing, and also that it may not be the best view to take anyway.
Recap:
Does the transistor internally depend on fields to operate? Yes, but that's not the whole picture. We have to consider the movement of charges too, and also taking the field view doesnt help when we have to deal with a transistor in the real world. Perhaps trying to predict new kinds of devices the quantum view is great, but we arent trying to do that here.