DC Network Theorems Unit 8 – Thevenizing a Bridge Circuit
UNIT 8 – THEVENIZING A BRIDGE CIRCUIT
UNIT OBJECTIVE
At the completion of this unit, you will be able to thevenize a resistive bridge circuit by using the
resistor divider equation.
UNIT FUNDAMENTALS
A resistive bridge circuit has 4 terminals, here labeled A through D. The source voltage (VS) is
applied across 2 opposing terminals (A and C). The output voltage is taken across the load
resistor (RL) connected between terminals D and B.
In this circuit, the bridge components are rearranged. Terminals D and B are the bridge output.
You can use the voltage divider equation or Ohm's law to determine the bridge output voltage
between D and B. This voltage is the Thevenin voltage of the bridge circuit.
To find the Thevenin resistance, replace the voltage source with a short circuit, and calculate
RTH between terminals D and B.
With the Thevenin voltage and the Thevenin resistance, the bridge circuit is simplified into a
Thevenin equivalent circuit. You can now use Ohm's law to determine the load voltage (VRL)
and the load current (IRL) for any value of RL.