UNIVERSITY OF MASSACHUSETTS DARTMOUTH
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
ECE 201
CIRCUIT THEORY I
THEVENIN EQUIVALENT CIRCUIT
BACKGROUND
Thevenin’s Theorem states that a linear circuit comprised of any number of voltage sources,
current sources, and resistors that supplies voltage and current to a load connected between two
output terminals (a and b) can be replaced by an “equivalent” circuit consisting of a single voltage
source and series resistor. This equivalent circuit will supply the same voltage and current to the
load as the original circuit.
PRELIMINARY WORK
Determine the Thevenin equivalent circuit for the loaded T network shown in Figure 1. Document
all of the steps and calculations involved in your lab notebook. Be sure to include a complete
circuit diagram for each circuit along with your calculations.
Vs
12 V
R1
R3
390 Ohm
120 Ohm
a
Rload
220 Ohm
R2
470 Ohm
b
Figure 1. A loaded T network
Run Multisim simulations to determine the expected values of the load voltage and current for
both the original and the Thevenin equivalent circuit.
PROCEDURE/RESULTS
Construct both the original and the Thevenin equivalent circuit on your breadboard.
For each circuit, measure the “open circuit voltage”, V Th, and the equivalent resistance, RTh.
Comment on your results.
Connect your ammeter and voltmeter to the a-b terminals as appropriate in order to measure the
load current and load voltage for each circuit. Compare your measurements with the expected
values from your simulation.