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posted by  carlos1978 on 11/6/2009 2:07:49 PM  |  status: Closed  |  Earned Karma: 25

Resolution by Thevenin

Course Textbook Chapter Problem Needs by
Analog Circuits Fundamentals of Electric Circuits (3rd) by Alexander, Sadiku 4 29 11/6/2009 at 4:00:00 PM
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Is there anybody can explain me how to fin the Thevenin equivalent circuit see by the 1k resistor (RTH and VTH).
I know that v0 = 3V but I want to resolve it by Thevenin. I also know that when I open the circuit by the 1K resistor, I don't have any current in the 3 mA branch. Thanx for your help.
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posted by Paul K on 11/7/2009 12:42:51 AM  |  status: Live
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Question Details:

Is there anybody can explain me how to fin the Thevenin equivalent circuit see by the 1k resistor (RTH and VTH).
I know that v0 = 3V but I want to resolve it by Thevenin. I also know that when I open the circuit by the 1K resistor, I don't have any current in the 3 mA branch. Thanx for your help.
     The 4k ohm , the 2k ohm resistors , and the dependant voltage source are irelevant as far as the Thevenin circuit the
1k ohm resistor sees . Instead of a 1k ohm resistor , let the load resistor value vary . The ideal 3mA current source
delivers 3mA to this load resistor no matter what its value is . For the circuit drawn , you said  and you are
right --- .What if the load resistor is doubled to 2k ohms ? We then have :
. What if we let the load resistor go to infinity ? This is the Thevenin voltage :
 . The short circuit current is :
. The Thevenin resistance is :
 . I know these values are strange ---- we do not encounter ideal sources in real life .
These values are not very useful either . The more useful equivalent circuit that the 1k ohm resistor sees is the Norton
circuit . The Norton current is  , and  the Norton resistance is .
This means we can replace the circuit with an ideal  current source in series with the 1k ohm resistor as far as
the 1k ohm resstor is concerned.
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