Hello
How does this thing work?
I know 3 legs Base, Investigator, Collector
What does a resistor in front of the base have to do with the transistor? Does the base influence the transistor's conduction? How do you calculate the resistance?
(1 votes)
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I still have an old Siemens Schuckert motor. I couldn't find the age on the nameplate.
Rudolf – very short:
1) Do you know the characteristic of a diode? Here, the width of the so-called “sperr zone” at the pn junction is reduced by an applied voltage in the flow direction (force effect of the E field) and thus allows an increasingly increasing current flow (e function between voltage and current).
2) Exactly the same runs on the pn layer between base and emitter – with a significant difference:
The barrier layer is influenced just as in the case of the diode, only the current to the very largest part does not flow between the base and the emitter, but the electrons are primarily sucked off to the collector (there: therefore “collector”), because the collet. Voltage is significantly greater than the base voltage (Uc>Ub, i.e. Ucb>0, i.e. C-B diode in the blocking direction).
This is the whole secret of the control of Ic by Ube, wherein the small base current Ib=Ic/B is a by-product that, although not desired, is unavoidable.
The factor B is, unfortunately, misleadingly referred to as “current amplification” – this has only historical reasons, as one of the largest developers of the transistor electronics (Barrie Gilbert) has shown. And this term has triggered many misunderstandings, because anyone who has not dealt with physics simply thinks: Aha – B is the current gain, so the input current is amplified….(one simply believes it).
The current flow Ic between the collet and emitter depends on the base current as a parameter: Here you can see the characteristic Ic(Uce) with Ib as a parameter.
https://pdf.direnc.net/upload/bc237-bc238-bc239-datasheet.pdf
As it works semi-conductor technology is very complex and for the applications 99% irrelevant.
How do I read this chart? What is UCE
Quote: “As it works semi-conductor technology is very complex and for the applications 99% irrelevant.”
But this is a very “cheering” statement. So you don’t have to understand anything – it’s enough to use “blind” any formulas?
For example, what do you answer to the question of how a simple current level from 2 transistors works? Ha – that doesn’t help you Ib at all! Do you need more examples?
The more current flows into the base (IB), the more current flows through collector and emitter (CE). But this is not linear (ICE = x * IB ) but follows these lines. Only at higher voltage UCE is the straight line.
Bravo! That’s what you meant.
Once again, is there something that should be adapted to the questioner’s level?
? What’s complicated here? That’s what you learn first when you’re dealing with transistors. I don’t know where to go without saying anything. The fact that someone knows what current and voltage is is probably to be presumed in the question. I didn’t deal with semiconductor physics…
You don’t even seem to be interested in where your mistakes are. Otherwise, you would have tried to respond logically and objectively to my statements (and to my questions!).
It’s really surprising how sensitive and insane some people react when you’re being contradicted. And much of what you wrote is proven to be wrong! If something is wrong and insane, I say/write it open. And that’s provocation? Already my first answer to you with the insane 99% (up to read) you have judged as “aggressive”. Well, everyone can make their own picture….
I won’t read anything from you in the future and I didn’t do it here either. As you seem to be just provocation, it would be a waste of time. Merry Christmas,…
Yeah, what should I say? So many inaccuracies and errors…
So the physical (you say “semiconductor technology”) mode of operation is 99% irrelevant? Have you ever explained or even developed circuits? Then you could not come to such a statement. In my long-term teaching, I felt this explanation as not “very complex” if one is confined to the essential principle (see my answer to Rudolf).
But you can’t think that seriously – there is no connection between cause and effect in the transistor?
Please don’t give me any statements I didn’t make. The question was “how does the transistor work exactly?” And that’s why I pointed out the important difference between a purely mathematical model description (which only applies under certain conditions and is physically wrong) and physical reality.
Aha – not so practical. Please look at the formula for voltage amplification of a transistor stage. There’s the steepness in the main transistor parameter! Anyone who has already designed an amplifier stage initially predetermines the necessary steepness (and thus the collapsing current).
Wrong! Take a look at the definition of saturation and realize that the relatively large base current is an FOLGE of the saturation state and not its cause – this is the opening of the base-collection. -Diode as a result of the sufficiently large voltage drop at the colliery resistance Uc
Without wishing to approach you, the difference between us is probably the concept of “physical reality”. You seem to be theoreticians and have all the side effects in mind, which increase complexity safely. On the other hand, I have worked in practice and teaching for a long time and I know what effects/explanations are primarily relevant in understanding.
I don’t need solid state physics or tape models. If, in the case of the diode, the properties of the pn junction in principle are understood, the transistor can also easily understand.
Finally, this was the question of Rudolf423, which I, although simplified, formulated, but hopefully in a short form, in response to Rudolf423.
(PS: A continuation of this dialogue does not seem sensible to me)
I wrote above: As it works semi-conductor technology is very complex and for the applications 99% irrelevant. And now you say I’m mentioning band structures. What is semiconductor physics for you? For me, this is the quantum mechanics of the solid. I barely know an electronic who dominates it (except in very rough ways).
Yes, it doesn’t say that, for example, the Ebers Moll model would be wrong. I just have your statement above
I mean. The transistor has characteristic curves and if I pre-set two sizes, the third one automatically adjusts. There is no point in talking about cause and effect.
For example, if I introduce Uce and Ube, then a certain Ib is set up and a certain Ic. However, the relationship between the predetermined Ube and the Ic is exponential and nonlinear.
If, on the other hand, instead of using a base current Ib, Ube automatically adjusts itself according to the characteristics and also the Ic. In this case, however, the relationship between Ic and Ib i.A. is quite linear. You also know that, but you suggest that this would be completely insignificant.
So why should I not say that the transistor can be well described by a current-controlled current source. Of course, it is also possible to consider the transconductance, but I do not find it so practical if, for example, it is a question of specifying an approximate working point or to dimension the basic resistance for a transitionor as a switch.
If I know that I need a certain base current for switching through as a switch, so that the transistor goes safely into saturation, then I can calculate this relatively easily by simply saying that I take about 0.7V for Ube and determines the current through the base resistance. In the end, it doesn’t matter if I accepted 0.7 or 0.65V.
Conversely, however, it is difficult to specify an exact voltage at which the transistor is saturated. This may vary by up to 50mV depending on the specimen scattering. Who exactly determines a working point by accurately defining Ube on mV?
At the current level, it’s another thing, and I didn’t say you were gonna knock the Ebers-Moll model.
You become agsressive to make others down, pretending you’ve been watching wisdom alone and being pissed right before you even understood what the other wants to say.
You make me up when I try to show that the “physical reality” lies in the band structure and solid state physics, here you enter the concept of physical reality but again wide. What do you understand? What is a good transistor model for you? I have obtained my doctorate in solid state physics and know how complex it will be if you want to describe semiconductors at a high physical level. Only at the same time there is hardly any intern who ever needs this academic knowledge if he is to dimension an amplifier, except one works as a chip designer – and often not even then.
Why don’t you just stay real – who mentioned “band structures”? If you understand the current level, you know that it is simply based on Vbe1=Vbe2, right?
What is my “examination” and when am I “aggressive”?
It’s funny – it’s you who suddenly becomes personal. I mentioned only technical aspects and tried to point out the fundamental difference between a “model” (which can serve a few purposes) and the physical reality.
Not bad, but in order to understand a current level, I don’t have to perform band structure calculations in the silicon. You don’t know why you’re getting aggressive here.
LOL
Between collector and emitter is a great resistance. When a voltage is applied to the base, this resistance becomes smaller.
The base thus functions like a tap with which it is possible to regulate the water flow (stream K-E).
https://www.youtube.com/watch?v=5wIRJN3DN_8