Superposition theorem

Thread Starter

metelskiy

Joined Oct 22, 2010
66
i have this circuit
lab 7_1.png
I got confused with positive and negative voltage supplies. In class we used only positive. I need to find voltage at point A using superposition theorem. Could someone please help me at least understand circuit? How would i redraw it in a more understandable way?
To start i know i have to short 12V source and leave -12V and calculate Voltage at A.
Than short -12v and leave 12v and calculate voltage at A again.
Than add those two values and it should be voltage at A for original circuit.
How would i treat that -12v souce? thanks.
 

shteii01

Joined Feb 19, 2010
4,644
You have two cases.

Case 1
12 V is shorted.
You have R1 parallel with R3, lets call it R1||R3.
The R1||R3 is in series with R2 and in series with -12 V source.
Draw this circuit, solve for what ever you need.

Case 2.
-12 V is shorted.
You have R2 parallel with R3, lets call it R2||R3.
The R2||R3 is in series with R1 and in series with 12 V source.
Draw this circuit, solve for what ever you need.

Like you said, add results from Case 1 and Case 2, that is your answer.
 

Thread Starter

metelskiy

Joined Oct 22, 2010
66
Ok here is another problem. I think i mainly understand it but if someone got time and patiance please check if i'm doing it right, first redrawing circuits. I'll need to find voltage at points A and B using superposition theorem.
Original (A and B on ends of R3):
lab 7_2.png
5V and -12V shorted:
lab 7_2_1.png
12V and -12V shorted:
lab 7_2_2.png
12V and 5V removed:
lab 7_2_3.png
 

Georacer

Joined Nov 25, 2009
5,182
Your circuit look good to me. You just didn't label the nodes A and B in the initial circuit so I can't comment on the correct node notation.
 
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