- #1

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**Summary::**So apparently the equations schould be correct but I am not sure about it.

Isnt R1 = Ub(10V) - Base voltage / Iq + Ib --> Ub is the source voltage 10V.

And schouldnt R2 be :base voltage / Iq?

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- Thread starter altruan23
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In summary, the equations shown in the conversation are correct. The confusion seems to stem from the different ways that voltage is expressed and the importance of defining a common reference point, or "ground," in circuit analysis. It is recommended to define and use clear and consistent notation to avoid confusion. It is also common practice to redraw and rename elements in a circuit to match preferred definitions.f

- #1

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Isnt R1 = Ub(10V) - Base voltage / Iq + Ib --> Ub is the source voltage 10V.

And schouldnt R2 be :base voltage / Iq?

- #2

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Too many definitions. V_{1} U_{B} ?

What is your question specifically?

What is your question specifically?

- #3

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- #4

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I don't understand. Your questions are exactly* what those equations say. I think your questions aren't so much about the physics of voltage drops across resistors and Ohm's law as they are about dealing with sloppy definitions. Define the voltages and currents carefully and try to be consistent in their use.Summary::So apparently the equations schould be correct but I am not sure about it.

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Isnt R1 = Ub(10V) - Base voltage / Iq + Ib --> Ub is the source voltage 10V.

And schouldnt R2 be :base voltage / Iq?

The equations shown are correct.

* Parentheses matter. When you write "Ub(10V) - Base voltage / Iq + Ib" This means ##U_B-\frac{U_{BE}}{I_q}+I_B## . I don't think that's what you meant.

- #5

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Arent we allowed to use only the voltage from Terminal B to ground? that means base voltage?

- #6

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So, The simple example I drew below shows how these representations are equivalent, provided you understand that the "ground" voltage ##V_0## has been defined to be zero and thus left out of the equations.

Also, once the ground voltage has been define to be zero, that applies to all of the circuit elements connected to that node. So this is the same as saying the emitter voltage in your circuit is defined to be zero and thus ##U_{BE}## could also be referred to as the base voltage (with respect to ground).

As a matter of style, to avoid confusion, I really dislike mixing the variables named ##U## and ##V## to express voltages. It is much easier to read the equations if there is a common standard notation.

Finally, I will add that in many decades of working with circuits like this, it has been really common for me to simply redraw and rename things in the circuit to match my preferred definitions. Otherwise things can get unnecessarily confusing.

- #7

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thank you very much for the long answer! very nice from you! it is clearer now! thanks again!

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