What is the Correct Calculation for Transistor Configurations?

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SUMMARY

The discussion focuses on the correct calculation methods for transistor configurations, specifically analyzing combinations of resistors R1 and R2. The user questions the validity of calculated values for base current (Ib) and emitter current (Ie) under different resistor configurations. Key formulas provided include Vb = R1/(R1+R2) * 10V, Ve = Vb - 0.7V, and Ie = Ve/Re. The user highlights that for the configuration of R1 = 1k and R2 = 10k, the transistor enters saturation, requiring more complex calculations.

PREREQUISITES
  • Understanding of transistor operation modes (cut-off, linear, saturation)
  • Knowledge of Ohm's Law and basic circuit analysis
  • Familiarity with transistor parameters (Ib, Ie, Ic, Vb, Ve)
  • Experience with resistor configurations in electronic circuits
NEXT STEPS
  • Study the derivation of transistor current formulas (I_C and I_E)
  • Learn about the impact of resistor values on transistor operation modes
  • Explore advanced calculations for saturated transistor configurations
  • Investigate simulation tools for circuit analysis (e.g., LTspice or Multisim)
USEFUL FOR

Electronics students, circuit designers, and engineers involved in transistor circuit analysis and design will benefit from this discussion.

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This is the result from a lab,but I am not sure the results are correct.

I guess the combination of R1=10k and R2=10k is under linear region,but how come the calculated Ib is zero.

For combination of R1=10k and R2=1k,Idon't know why the Ie is negative.Negative value means error?Is it the cut off mode?

And for combination of R1=1k and R2=10k,it should be in saturation?
I guess either the measured or calculated result is wrong.What is the problem?

Also,there are many differences(highlighted).Is my calculation wrong?
 

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How did you get the formulas for I_C and I_E? One of them is wrong, but as there is no explanation where they come from and what you did there it is hard to tell which one.
 
Just to give you general guidance, your results should be
Vb = R1/(R1+R2)10V
Ve = Vb - 0.7V
Ie = Ve/Re
Ib ~ 0
Ic ~ Ie
Vc = 10V - Ic*Rc
Vrc = 10V - Vc

EXCEPT for R1 = 1K, R2 = 10K. For this configuration the transistor is saturated and the computation is more laborious. If you want to attempt it, assume Vc = Ve, write 2 equations in unknowns Ib and Ve. Vb is still Ve + 0.7V.
 

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