Another problem, voltage characteristic in a diode circuit

AI Thread Summary
The discussion revolves around calculating the base current (I_B) in a diode circuit using Ohm's Law and Kirchhoff's Voltage Law (KVL). The user initially questions whether I_B can be determined simply as Vi/Ri. They receive suggestions to consider the diode drop and the characteristics of a bipolar junction transistor (BJT) in their calculations. After attempting KVL on a specific mesh, the user proposes a calculation that yields I_B as 93.75 microamps, expressing uncertainty about the accuracy of their assumptions. The conversation highlights the importance of understanding diode characteristics and circuit analysis techniques for accurate current calculations.
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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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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