Winterstone:
Yes you are, now get to work or else you get graded with an "F" for this semester and i have to call your parents on the phone
Seriously though, you didnt want to do the original circuit and asked for a new circuit, and i provided one and you did not like that one either, so i provided another one with all the things you wanted and now you say you dont want to do it. Why even bother responding in this thread if you dont want to do the circuit posted in the thread? Start your own thread and do the circuit you want done then. It's that simple.
All:
See, as predicted there is still no analysis of the circuit i wanted to see (except by those who already had done so and didnt constantly complain about the circuit)
Sorry to say - you didn`t understand anything. Instead - you can answer in a polemic way only.
Several times I have stated that it does not matter if I "like" or "dislike" a circuit - and I have shown you what authors with excellent reputation think about the configuration as proposed by you ("disaster").
I have seen no reason to follow your desire and apply basic rules (Ohm`s law, KVL,..) to an unrealistic circuit.
By the way: what is the reason you want me to analyze "your circuits"? I am not in an examination!
There is no need to start my own thread because I have no problems (that means no open questions).
All I have tried up to now is to convince you that there are two commonly used bias schemes that work much more better than "your circuit".
And - in contrast to your statements - I have done a calculation (post#16).
However, you ignore every substantial answer - a very unfortunate discussion (better: exchange of opinions).
I will stop it now from my side.
Respectfully yours
Winterstone
A final remark: Why didn`t you comment the very informative contribution from Claude Abraham (post#73)?
Excerpts:
"The circuit in post #1 can never be employed, regardless of application, "
"Using Ib to control Ic is not good, because of beta variation. "
Yes, there are some assumptions in the first circuit. But as i said later, i have changed the circuit (adding 3 resistors) to accommodate the replies yet i still get a lot of criticism about the circuit
Hello Al,
As you certainly know the circuit in your first post is just a model or a symbol saying how a transistor can be biased.
So in your first pic, becuase you did not use a resistor for the base of the transistor, can we assume that the transistor is in saturation or so called hard saturation? If we try to do such an assumption then we can simply solve it and calculte Ic.
Hi again Wizard,
No it is not in saturation, and Vbe is quite low for that transistor. So assume it does not burn
Also note that later we *measure* Vbe after it has been biased with large resistors.
hi wiz,
Just for reference is MrAl's original circuit running in LTSpice.
Its not a serious circuit design, its only to demonstrate a problem.
Image03 shows the effect of temperature from 0C thru 100C
E.
Wizard:
Look at the circuit in post #77 now.
Hello again,
That is what we would like to do, using the two different methods
1. Voltage control
2. Beta (current control)
Hello there Claude,
First, sorry i didnt reply to your other post which was very good. I wanted to wait until the smoke cleared from the other discussions if you know what i mean
I was actually hoping that people would come up with ways to calculate this kind of circuit, with or without extra resistors. My main goal is to compare methods and see what happens. I started this thread because someone suggested that the voltage control method is better than the current control method using Beta, so i had hoped to see how this works or else disprove it. But i am open to suggestions that show that one method is better than the other for some reason, ----- And yes if you would care to show a couple bias networks that would be just fine too. We can look at them in different ways and see what we come up with. The only thing that i ask is that you use a common transistor like the 2N2222A as i suggested or the 2N3904 like audioguru suggested. If people want to try this with a real circuit they have to be able to get the transistor without too much difficulty.
LOL... Guys... I'm sure MrAl was fully aware of this from the start. This is like grade school knowledge of the electronics world. From what I was reading, he was not defending the circuit and it's practical use. That is not really the issue under debate. To paraphrase Eric, "you are moving the goalposts" (changing the argument) if you keep going on and on about the failures of that one circuit. The circuit is not the issue. The circuit obviously sucks.Multiple people said:That circuit sucks bad, don't ever use it.
This is a funny little thread. I hesitated to join sooner as I am not strong in the maths. But I conferred with MrAl and he convinced me.
The mistake
The disparity in the two sides on this issue seems to be due to the difference in the analyzing of a circuit and analyzing of tools, for analyzing circuits.
LOL... Guys... I'm sure MrAl was fully aware of this from the start. This is like grade school knowledge of the electronics world. From what I was reading, he was not defending the circuit and it's practical use. That is not really the issue under debate. To paraphrase Eric, "you are moving the goalposts" (changing the argument) if you keep going on and on about the failures of that one circuit. The circuit is not the issue. The circuit obviously sucks.
The point
What I believe MrAL is really saying, and I would have to agree, is that favoring one of the two proposed methods as a tool to analyze any such circuit, crappy or not, makes no difference whatsoever. To me, thats a given. It's like arguing over which is a more valid way to measure automobile velocity. In miles per hour? Car lengths per minute? Or a tire circumference vs RPM? Although they seem somewhat different, they all equate to the same thing in the end. Distance/Time.
Or to be specific.
The forward voltage drop of Vbe will be about 0.65 volts. But it's EXACT (to more significant digits) momentaneous voltage drop is directly dependant on the current through it. The parameters are fundamentally related to each other, connected at the hip, inseparable, best friends, mates, pals, et cetera. This is obvious, it's basic Ohm's law. The current through a resistance (Ibe) determines the voltage across it (Vbe). This is why a transistor can internally be a voltage controlled system, but also can be current controlled at the same time. And also why a method focusing on one of the parameters can just as easily be adapted to use the other. So there is no point in saying one is better than the other, QED... it's just like Distance/Time above.
It seems to me everyone opposing MrAl's view just wants to focus on why the circuit sucks, and not ways we can analyze why the circuit sucks.
Transistor Maths
As for a formula that can be used to calculate a transistor general parameters without knowing Hfe/β, I don't think such a thing exists. As amplifying devices, β is the most important factor, this is the gain of the transistor, it's the reason for having a transistor. To suggest that the β of a transistor can be canceled out or ignored in an equation is quite preposterous. It's like trying not to use the capacity of a capacitor, or the resistance of a resistor in a circuit calculation.
Now... there are circuits that exist that intentionally make these factors less meaningful when need be, but really that is apples and oranges.
Transistor Alpha
The transistor alpha certainly is a real parameter of a transistor, to be sure. And it is very "progressive" or "out of the box" thinking to try and use it for something meaningful. But as far as I know, transistor alpha only plays an important role with common-base configurations, and can almost always be considered unity. It's not really a gain factor, as much as it is attenuation.
So again, kinda apples and oranges.
One interesting thing is that α and β are related to each other via this formula.
View attachment 74053
But other than that, alpha is rather useless for analyzing a transistor from what I know.
This is a funny little thread. I hesitated to join sooner as I am not strong in the maths. But I conferred with MrAl and he convinced me.
The mistake
The disparity in the two sides on this issue seems to be due to the difference in the analyzing of a circuit and analyzing of tools, for analyzing circuits.
LOL... Guys... I'm sure MrAl was fully aware of this from the start. This is like grade school knowledge of the electronics world. From what I was reading, he was not defending the circuit and it's practical use. That is not really the issue under debate. To paraphrase Eric, "you are moving the goalposts" (changing the argument) if you keep going on and on about the failures of that one circuit. The circuit is not the issue. The circuit obviously sucks.
The point
What I believe MrAL is really saying, and I would have to agree, is that favoring one of the two proposed methods as a tool to analyze any such circuit, crappy or not, makes no difference whatsoever. To me, thats a given. It's like arguing over which is a more valid way to measure automobile velocity. In miles per hour? Car lengths per minute? Or a tire circumference vs RPM? Although they seem somewhat different, they all equate to the same thing in the end. Distance/Time.
Or to be specific.
The forward voltage drop of Vbe will be about 0.65 volts. But it's EXACT (to more significant digits) momentaneous voltage drop is directly dependant on the current through it. The parameters are fundamentally related to each other, connected at the hip, inseparable, best friends, mates, pals, et cetera. This is obvious, it's basic Ohm's law. The current through a resistance (Ibe) determines the voltage across it (Vbe). This is why a transistor can internally be a voltage controlled system, but also can be current controlled at the same time. And also why a method focusing on one of the parameters can just as easily be adapted to use the other. So there is no point in saying one is better than the other, QED... it's just like Distance/Time above.
It seems to me everyone opposing MrAl's view just wants to focus on why the circuit sucks, and not ways we can analyze why the circuit sucks.
Transistor Maths
As for a formula that can be used to calculate a transistor general parameters without knowing Hfe/β, I don't think such a thing exists. As amplifying devices, β is the most important factor, this is the gain of the transistor, it's the reason for having a transistor. To suggest that the β of a transistor can be canceled out or ignored in an equation is quite preposterous. It's like trying not to use the capacity of a capacitor, or the resistance of a resistor in a circuit calculation.
Now... there are circuits that exist that intentionally make these factors less meaningful when need be, but really that is apples and oranges.
Transistor Alpha
The transistor alpha certainly is a real parameter of a transistor, to be sure. And it is very "progressive" or "out of the box" thinking to try and use it for something meaningful. But as far as I know, transistor alpha only plays an important role with common-base configurations, and can almost always be considered unity. It's not really a gain factor, as much as it is attenuation.
So again, kinda apples and oranges.
One interesting thing is that α and β are related to each other via this formula.
View attachment 74053
But other than that, alpha is rather useless for analyzing a transistor from what I know.
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