Biomedical Engineering Reference
In-Depth Information
Next, consider finding the response,
V
0
5
, due to the 5 A source, with the 10 V source dead.
3V
0
5
I
5
3
Ω
B
+
5
Ω
+
5 A
V
0
5
2
Ω
V
5
5
-
-
First combine the two resistors in parallel (3
O k
2
O
), giving 1.2
O
.
V
0
5
is easily calculated by
Ohm's law as
V
0
5
¼
5
1
:
2
¼
6V
:
KCL is then applied at node B to find
I
5
, giving
3
V
0
5
þ
I
5
5
¼
0
With
V
0
5
¼
6V,
I
5
¼
3
6
þ
5
¼
23 A
:
Finally, apply KVL around the closed path
V
0
5
5
I
5
þ
V
5
5
¼
0
or
V
5
5
¼
V
0
5
þ
5
I
5
¼
6
þ
5
23
¼
121 V
:
The total response is given by the sum of the individual responses as
V
5
¼
V
5
10
þ
V
5
5
¼
64
þ
121
¼
185 V
9.7 TH
´
VENIN'S THEOREM
Any combination of resistances, controlled sources, and independent sources with two
external terminals (A and B, denoted A,B) can be replaced by a single resistance and an
independent source, as shown in Figure 9.22. A Th´venin equivalent circuit reduces the
original circuit into a voltage source in series with a resistor. This theorem helps reduce
complex circuits into simpler circuits. We refer to the circuit elements connected across
the terminals A,B (that are not shown) as the
load.
The Th´venin equivalent circuit is
