# Emitter, Collector, Transistors...?

Discussion in 'Homework Help' started by missfangula, Sep 20, 2010.

1. ### missfangula Thread Starter New Member

Sep 14, 2010
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0
Hello All,

I am currently stuck on a circuits homework problem...the book is not much help, and I cannot find anything online similar to the circuit I am having to understand, so any insight is much appreciated.

I have a circuit with two resistors, Rb, and Re, Rb connected to ground V and to transistor, and Re connected to the same transistor and to -15 V voltage source. The collector end of the transistor is connected to a +15 V.

What is Vb, Ve, and Vc (base, emitter, and collector voltage drop)?

-miss fangula

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2. ### Georacer Moderator

Nov 25, 2009
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Is this a completely theoretical question, or it comes with numbers you forgot to provide?

3. ### missfangula Thread Starter New Member

Sep 14, 2010
9
0
Sorry, beta = 180, Rb = 820 ohms, Re is 3.3 kOhms.

Thanks again!

4. ### missfangula Thread Starter New Member

Sep 14, 2010
9
0
Also, this is an NPN bipolar transistor.

5. ### Georacer Moderator

Nov 25, 2009
5,177
1,285
First, let setup our set of equations:

We have:
$I_E=\beta \cdot I_B \ and\\
0=I_B \cdot R_B +0.7+I_E \cdot R_E -15\ \text{according to Kirchoff's Voltage Law for the mesh I have indicated}$

Do you understand on what ground I have written these equations? Can you solve the system yourself? As for the Vc, you can see for yourslef that it is connected to the voltage supply, making it 15V.

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