View attachment 279905
MrAl - hello again,
Let me first say that I think it's good that you didn't act on your announcement (" Im sorry but i have no option but to ignore any other replies from you for this circuit.2)
It may be that I have been a little too direct (perhaps rude?) in my responses and assessments. I'm sorry about that, but I still think that in technical discussions you have to be direct and unambiguous to avoid being misunderstood.
Maybe I should try to be a bit more diplomatic with my words.
In this context, please also take into account that I cannot write in my native language here.
On the other hand, I do not like to talk around the subject for a long time - I prefer to say clearly my opinion.
So back to the main point of this discussion ("Thoughts on the T-model").

I have extracted here again the model of the transistor shown by you in the two diagrams (Post#1, circuit 1 and circuit 2) ):
Circuit 1 with R5=0 and
Circuit 2 with R5=14 ohms.

Now I have the following questions about it:
1.) Are both models equivalent, or do you prefer one of them?
2.) Do the models apply for large signals (DC) or for small signals (ac) or for both cases?
3) Do both models fulfill the equations which are important for practical applications:
* For DC:
Ib=Ic/B and Ic=f(Vbe) ?
* For ac:
ic=beta*ib ; ic=gm*vbe ; r_pi(=rbe=h11=hie)=vbe/ib=beta/gm ?
4) How should the models be evaluated in comparison to the models discussed in the literature so far (two pi-models, T-model)?

Thank you.

Hello again,

Oh i did not realize you were not writing in your native language i think that is because your use of language seemed very good to me so i did not notice anything wrong like that. Can i ask what your native language is, but if you care not to say that's ok.

I'll try to answer these but may have a problem with one or two of them.
1. The first step with R5=0 is the T model proper for calculating R5. The second step with R5=14 is the T model proper for calculating the AC gain, after calculating R5 when R5=0 in the first step.
2. The first step is the T model proper for the DC bias so i guess we would call that large signal. The second step is for the T model proper for AC gain so we would call that small signal.
3. Ic=Ib*B so yes Ib=Ic/B, not sure about Ic=f(Vbe) i think that would be something you would use although we could look into that too.
Also for #3, ic=B*ib although it is more like increment_in_ic =B*increment_in_ib.
Not sure about ic=gm*vbe yet, dont deal with r_pi at all yet although that could be incorporated later.
4. I only address the T model so far as discussed in 1 and 2 above. The analysis shown so far works in that way. To calculate everything though every single part in the two schematics is used in the calculation, with two calculations one for each schematic (top and bottom schematics).

I hope that helps.

 

Hello again,
Oh i did not realize you were not writing in your native language i think that is because your use of language seemed very good to me so i did not notice anything wrong like that. Can i ask what your native language is, but if you care not to say that's ok.

I am from Germany.

As far as your technical-oriented information is concerned, I think it would be helpful to show how and why you model works using a suitable simple example circuit (gain stage).
I know that you have done this already - however, with consideration of finite capacitor impedances (and, hence, frequency dependent. Therefore, it is not easy to compare your models with the existing ones.
Thank you.

 

I am from Germany.

As far as your technical-oriented information is concerned, I think it would be helpful to show how and why you model works using a suitable simple example circuit (gain stage).
I know that you have done this already - however, with consideration of finite capacitor impedances (and, hence, frequency dependent. Therefore, it is not easy to compare your models with the existing ones.
Thank you.

Oh ok and i would have guessed that you were from there. One of my grandfathers was from there but he became an American citizen.
I'll try to draw something more up that might help.