Class Activity (week 3)

This week node voltage and mesh current analysis teach. When a dependent or independent voltage

source is between two essential nodes, this is a super node. Voltage source can temporary delete in

this situation. According to Fig 1, independent voltage source between V2 and Vx is inside a super

node. Equations in the figure 1 show that Vx = 30 volts.

Figure 1: Super Node in a DC Circuit

In the below circuit a mesh current method use. There is two essential nodes and three branches, and

two loops choose. Two KVL are written for each loop, and a system equation with three independent

variable are solved by Cramer's Rule. Also current in the middle branch is i1 plus i2.

Figure 2: Mesh Current Method 

When a dependent or independent current source is between two essential nodes, this is a super

mesh. Current source can temporary delete in this situation, but its effects will consider in KVL.

The independent current source in the second loop is in the super mesh. This current source delete,

but it determine that i2 - i3 = 3A.

Figure 3: A super Mesh in a DC Circuit

Everycircuit.com is a cite that help people make their circuit easily.

Figure 4: Everycircuit.com

A NPN bipolar transistor as a current control a current source is connected, and its gain calculated.

α = β / (β + 1) , α = 50 / ( 50 + 1 ) = 0.98039

α = IC / IE , α = 8.25 mA / (0.165 + 8.25) , α = 0.98039

Figure 5: A Bipolar Transistor