The George Washington University
School of Engineering and Applied Science
Department of Electrical and Computer Engineering
ECE 11  Fall 2003
Experiment # 2
DC Series and Parallel Circuits
Equipment:
2 Keithley Model 175 Digital
Multimeter (DMM)
2 Pair of Banana to minigrabber test leads
1 Prototype Bread Board
1 Agilent E3631A Triple Output DC Power Supply
Components:

R1  470 Ohm Resistor

R2  560 Ohm Resistor

R3  680 Ohm Resistor

R4  750 Ohm Resistor

R5  820 Ohm Resistor

R6  1 K Ohm Resistor
Objectives:

Determine the value of resistors according
to their color
codes.

Measure the value of resistors with
an Ohm Meter.

Connect electronic components in series
or parallel combination on your solderless bread board.

Measure the total resistance in a series/parallel
circuit.

Calculate the equivalence resistance
in a series/parallel circuit using nominal and measured values.

Calculate the total current in a series/parallel
circuit for a given applied voltage.

Calculate the voltage drop across all
components in a series/parallel circuit.

Calculate the expected total power dissipated
in a series/parallel circuit from nominal and measured values.

Set the voltage on a power supply.

Limit the current on a power supply.

Make power supply connections to a circuit.

Measure the actual voltage drop across
all components.

Measure the actual current through each
component.

Find the actual power dissipated in
each component of a series/parallel circuit.

Create a data table.

Experience the limit of the DMM.
1. DC Power Supply Set
tup
In this section you will learn in detail on how to supply voltage and
current to your circuit using power supply equipment available in the lab.
Consult the instruction manual for the Agilent E3631A Triple Output
DC Power Supply and explain, step by step with a block diagrams
if necessary:
1.How would you set the power supply to get a 3.6V voltage.
Use DMM to verify the voltage.
2. How to limit the current to 100mA Use DMM to verify the current
limit.
3. How to connect the power supply to your breadboard.
Figure 1A
Figure 1B
Figure 1C
2. (PreLab
H/W) Equivalence DC Resistance
Based on the class notes, you should
be familiar with the concept of resistors in series and resistors in parallel.
In this section you are asked to simplify circuits given to find their
equivalence resistance.

DERIVE an equivalence
DC resistance (Reqv) general formula for circuit of Figure 1A.
DO NOT substitute values into the resistors yet. Leave the resistors
in their reference designator symbol. Show the detail steps on how
you simplify the circuit and finally give the final formula of the
Reqv of Figure 1A.

DERIVE an equivalence
DC resistance (Reqv) general formula for circuit of Figure 1B.
DO NOT substitute values into the resistors yet. Leave the resistors
in their reference designator symbol. Show the detail steps on how
you simplify the circuit and finally give the final formula of the
Reqv of Figure 1B.

DERIVE an equivalence
DC resistance (Reqv) general formula for circuit of Figure 1C.
DO NOT substitute values into the resistors yet. Leave the resistors
in their reference designator symbols. Show the detail steps on how
you simplify the circuit and finally give the final formula of the
Reqv of Figure 1C. [Hint] You will have to do some transformation
to simplify the circuit.
3.  (PreLab
H/W) DC Calculations
In this section you will do some ORCAD simulation and mathematic calculation
to find voltage, current and power dissipation of each resistor in the
three circuits given. In the simulation, use nominal values
of resistors given in the component section of this report. Use V1
= 3.6 Vdc.
3A. For the circuit of Figure 1A:

Calculate the equivalent resistance (Reqv).

Find the expected voltage drop across each resistor.

Find the expected current through each resistor.

Find the total current(Itotal).

Calculate the power dissipated by each resistor.

Create Data Table 3A  Calculated Values of Figure 1A with the above information
in it.
3B. For the circuit of Figure 1B:

Calculate the equivalent resistance (Reqv).

Find the expected voltage drop across each resistor.

Find the expected current through each resistor.

Find the total current(Itotal).

Calculate the power dissipated by each resistor.

Create Data Table 3B  Calculated Values of Figure 1B with the above information
in it.
3C. For the circuit of Figure 1C:

Find the equivalent resistance (Reqv).

Find the expected voltage drop across each resistor.

Find the expected current through each resistor.

Find the total current(Itotal).

Calculate the power dissipated by each resistor.

Create Data Table 3C  Calculated Values of Figure 1C with the above information
in it.
4.  DC Measurement
In this section you will construct the circuits of Figure 1A, Figure
1B and Figure 1C. You will then do some detailed measurement to find
voltage, current and power dissipation of each resistor in the three circuits
given. Use V1 = 3.6 Vdc.
4A. For the circuit of Figure 1A:

Construct the circuit of Figure 1A. DO NOT connect the power supply
(V1) to the circuit yet. Use DMM to measure the equivalent resistance
(Reqv) of Figure 1A.

Connect the power supply (V1=3.6 Vdc) to the circuit. Use DMM to
measure the voltage drop across each resistor.

Use DMM to measure the current through each resistor in the circuit.

Measure the total current(Itotal) used by circuit.

Calculate the power dissipated by each resistor.

Create and complete Data Table 4A  Measured Values of Figure 1A with the
above information in it.
4B. For the circuit of Figure 1B:

Construct the circuit of Figure 1B. DO NOT connect the power supply
(V1) to the circuit yet. Use DMM to measure the equivalent resistance
(Reqv) of Figure 1B.

Connect the power supply (V1=3.6 Vdc) to the circuit. Use DMM to
measure the voltage drop across each resistor.

Use DMM to measure the current through each resistor in the circuit.

Measure the total current(Itotal) used by circuit.

Calculate the power dissipated by each resistor.

Create and complete Data Table 4B  Measured Values of Figure 1B with the
above information in it.
4C. For the circuit of Figure 1C:

Construct the circuit of Figure 1C. DO NOT connect the power supply
(V1) to the circuit yet. Use DMM to measure the equivalent resistance
(Reqv) of Figure 1C.

Connect the power supply (V1=3.6 Vdc) to the circuit. Use DMM to
measure the voltage drop across each resistor.

Use DMM to measure the current through each resistor in the circuit.

Measure the total current(Itotal) used by circuit.

Calculate the power dissipated by each resistor.

Create and complete Data Table 4C  Measured Values of Figure 1C with the
above information in it.
5. Design, Build and Test the Voltage Ladder
In this section, you are asked to design a voltage ladder using the
concept of Voltage Divider. Use circuit of Figure 1A and find the
appropriate values of R1, R2, R3 and R4 to build a voltage ladder with
the following specifications:
Total Power Consumed (Ptotal): < 0.18
Wdc
Power Supply (V1) : 12 Vdc + 5%
VAB: 1.5 Vdc + 5%
VBC: 2.5 Vdc + 5%
VCD: 3.5 Vdc + 5%
VDE: 4.5Vdc + 5%
All resistance must be greater than 100 Ohm.
Find the node voltages associated with A, B, C, D and E.
Test your circuit and check whether the specification is satisfied.
6. Conclusions

Compare the calculation results from
section 3 to measurement results from section 4 on the circuits of Figure
1A, 1B and 1C. If there are differences between the calculated and
measured results, include a discussion on why the differences happen..

Explain the concept of tolerance in
all the devices and equipment and how to get around the problem of inaccurate
measurement.
Modified to HTML format by Faisal
Mohd Yasin, cepus@seas.gwu.edu, Sept. 2001.
Modified by Yang Cao, ycao@gwu.edu,
Sept. 2003