Another problem, voltage characteristic in a diode circuit

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Discussion Overview

The discussion revolves around calculating the current I_B in a diode circuit, specifically in the context of a problem involving a bipolar junction transistor (BJT) and applying Kirchhoff's Voltage Law (KVL). The scope includes theoretical understanding and mathematical reasoning related to circuit analysis.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant suggests using Ohm's Law (I_B = V_i/R_i) to find the current I_B, indicating a basic approach to the problem.
  • Another participant recommends applying Kirchhoff's Voltage Law (KVL) and factoring in the diode drop and input voltage (V_i) for a more accurate analysis.
  • A participant expresses uncertainty about the BJT terminology and seeks clarification on the concept.
  • A later reply attempts to apply KVL to the circuit, proposing a relationship between the voltages and arriving at a calculated current of 93.75 microA, but questions the validity of the assumptions made in the calculation.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the best approach to solve the problem, with differing opinions on the application of Ohm's Law versus KVL and the assumptions made in calculations.

Contextual Notes

There are unresolved assumptions regarding the values used in calculations, such as the diode voltage drop and the input voltage, as well as the accuracy of the derived current.

amitjakob
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Good morning lovely people !

As I got some really helpful advice here yesterday i though i'd try it again, hopefully you haven't yet had too much from me (-:

So my question is concerning the attached PDF file (Last problem #3)

i am asked to find the current I_B in 3a) and 3c) but to my very low understanding wouldn't it simply be Vi/Ri (Ohms Law) ??

Thanks for the patience :smile:
 

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Engineering news on Phys.org
try kvl. looks like its a bjt (just zoomed in). factor in diode drop, Vi, etc etc
 
Thanx but ...

do you mind explaining a little bit more, I'm kinda newbie (-:
whats a bjt ?
thanks for the patience:cool:
 
edmondng said:
try kvl. looks like its a bjt (just zoomed in). factor in diode drop, Vi, etc etc

Tried KVL on the most left handside mesh.
Im not sure its right though ...

i guessed V_Ri + V_B = V_i then substitute V_B=0.65V (pretty sure its a bad guess) and V_i=1V (Which is given)

Yeilds I_Ri=I_B= 93.75 microA ? makes sense ?
 

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