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BJT Transistor operation on simple transistor-zener voltage regulator circuit

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Why does it matter whether the current is going through a resistor or not? It still is current, and current in a series circuit is the same everywhere. Regardless whether it is coming from a voltage source, current source or potato battery.

Good question. The answer is that the results due to the behavior of a device will be different depending on whether it is driven by a voltage source or current source. Take a resistor in series with other components, for example. If it is driven by a voltage source, and it increases in value due to temperature changes, it will take more voltage for itself, and the remaining components in series with it will have less voltage. If it is driven by a current source, the rest of the series components will not be affected by the change in value of the resistor.

The changes can be more profound if the voltage or current source drives a active component like a BJT.

Ratch
 
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A black box view is am empirical model which does not tell you how a transistor works, only what it does. I am sure they are useful, but not for understanding how a transistor works. I do agree with you on a lot of things, But not on whether a lone BJT is anything other than a transconductance amplifier.
Okay, I think I understand the crux of our discussion differences. We're not really discussing the same thing and thus (I think) have no basic disagreement.
My discussion relates to the best way to do circuit design with the BJT and you are mainly concerned with the purity of understanding of how it "works". But how a transistor works as a transconductance device under small signal conditions is not the same as how it appears to practically behave under large signal conditions. Those two modes of operation are quite different, (I trust you understand the differences) and can't be readily lumped together from a circuit design perspective.

The black-box current-controlled current-output model (especially with a diode added internally to model the base-emitter voltage/current relation) shows the external behavior of the device with sufficient accuracy to be very useful for large signal circuit design, and thus that model is invariably used for such design.
Trying to use the transconductance model for that would be very awkward and difficult, rather like a square-peg in a round hole.

I know you will continue on your endless Quixote journey to inform the unwashed of how a BJT really works, but please keep that separate from the practical aspects of designing with that transistor type in large signal applications, where the current-controlled current-source model is very useful and the transconductance model is not.
To do otherwise is to confuse the issue for those of limited knowledge (many on these forums) who are trying to do large signal design with BJTs. And (call me optimistic) I trust your posts are intended to help those forum members.

The transconductance model is appropriate and very useful, of course, for small signal design.

Cheers
 
Okay, I think I understand the crux of our discussion differences. We're not really discussing the same thing and thus (I think) have no basic disagreement.
My discussion relates to the best way to do circuit design with the BJT and you are mainly concerned with the purity of understanding of how it "works". But how a transistor works as a transconductance device under small signal conditions is not the same as how it appears to practically behave under large signal conditions. Those two modes of operation are quite different, (I trust you understand the differences) and can't be readily lumped together from a circuit design perspective.

Before I can agree to that I have to know what you mean by large signal conditions. Does the large signal still keep the transistor in the linear active region, or does to take it to saturation or cutoff?

The black-box current-controlled current-output model (especially with a diode added internally to model the base-emitter voltage/current relation) shows the external behavior of the device with sufficient accuracy to be very useful for large signal circuit design, and thus that model is invariably used for such design.
Trying to use the transconductance model for that would be very awkward and difficult, rather like a square-peg in a round hole.

I am not pushing any model for design work. Sedra and Smith show four different models for a BJT, specifically current, voltage, transresistance, and transconductance. I only said that in its bare native mode, it operates as a transconductance amplifier for small signals.

I know you will continue on your endless Quixote journey to inform the unwashed of how a BJT really works, but please keep that separate from the practical aspects of designing with that transistor type in large signal applications, where the current-controlled current-source model is very useful and the transconductance model is not.
To do otherwise is to confuse the issue for those of limited knowledge (many on these forums) who are trying to do large signal design with BJTs. And (call me optimistic) I trust your posts are intended to help those forum members.

Personal hygiene is not a factor in understanding how a BJT works. I did not speak about design in this thread.

The transconductance model is appropriate and very useful, of course, for small signal design.

As are the other models.
 
Before I can agree to that I have to know what you mean by large signal conditions. Does the large signal still keep the transistor in the linear active region, or does to take it to saturation or cutoff?
It can be in any of those regions.
Large signal means that the small signal linear approximations don't work such as a fixed value for gm.
I am not pushing any model for design work. Sedra and Smith show four different models for a BJT, specifically current, voltage, transresistance, and transconductance. I only said that in its bare native mode, it operates as a transconductance amplifier for small signals.
Okay.
Personal hygiene is not a factor in understanding how a BJT works. I did not speak about design in this thread.
I don't know whether you don't understand the idiom or you're trying to be funny(?).

You "did not speak about design in this thread" yet it should have been apparent that was the point of my responses.
So either you did not understand that or purposely ignored that.
Either way I obviously wasted my time responding to you.
You can be certain that won't happen again.
 
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Either way I obviously wasted my time responding to you.
You can be certain that won't happen again.

Welcome to the club.
 
On the very first post, the OP requesting help wrote this particular sentence:

"Simple words because I am just a hobbyist. Thank you!"

Which apparently fell on deaf ears to a pedantic writer in this thread. His stubborn adherence to minutiae and his emphasis on a no-holds-barred discussion, while probably correct, has scared the hobbyist away.
 
On the very first post, the OP requesting help wrote this particular sentence:

"Simple words because I am just a hobbyist. Thank you!"

Which apparently fell on deaf ears to a pedantic writer in this thread. His stubborn adherence to minutiae and his emphasis on a no-holds-barred discussion, while probably correct, has scared the hobbyist away.

Evidently you did not read my post #5 where I did answer the OP's question simply and directly. He must have been satisfied, because he did not ask any more questions about what I said. The rest of my posts were addressed to other members participating in this thread, and the OP was under no obligation to read them or participate. Could you be a little more specific and name the words that were not "simple". By the way, I am just a hobbyist myself.

Ratch
 
Enough!

Where did I put my BIG KEY ?

JimB
 
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