Experiment 1
DC Meters and Measurements
John Nosek
ENEE 206
Section 101
Lab Report 1
2/17/04
● Objective
Use a DC multimeter to measure the currents, voltages, and resistance in a resistor circuit
and diode circuit. Plot the I-V characteristics of each circuit based on the data recorded.
● Equipment
- DC Power Supply
- Digital Multimeter
- Breadboard
- Diode
- 20 kΩ Potentiometer
- 2 Resistors of unknown values
● Schematics
Resistor Circuit
I
Potentiometer
A
+
DC
12V
+
_
R
V
_
V
Diode Circuit
Diode
I
I
V
R
+
_
DC
0-20V
● Procedure
For the resistor circuit, one of the unknown resistors was placed into the circuit
according to the schematic. The potentiometer was then set to five different settings and
at each setting, the amperage in the circuit was measured at position A and the voltage in
the circuit was measured at position V. The same procedures were then repeated for the
second unknown resistor.
For the diode circuit, the voltage going into the circuit was varied from 1 to 10 V
DC. At each 1 volt increment, the voltage in the circuit was measured at position V and
the amperage in the circuit was measured at position I. Then the polarity of the voltage
into the circuit was reversed and the same procedures stated before were repeated.
● Results
Resistor 1 Circuit
I
8.18 mA
1.56 mA
.96 mA
.65 mA
.16 mA
V
11.98 V
2.278 V
1.402 V
.949 V
.221 V
R
1.4645 kΩ
1.4602 kΩ
1.4604 kΩ
1.4600 kΩ
1.3813 kΩ
I-V Curve for Resistor #1
12
V - Voltage (Volts)
10
8
6
4
2
0
0
1
2
3
4
5
I - Amperage (mA)
Mean Resistor Value = 1.44528 kΩ
Actual Resistor Value = 1.469 kΩ
6
7
8
9
Resistor 2 Circuit
I
.62 mA
.37 mA
.25 mA
.16 mA
..04 mA
V
12.00 V
7.32 V
4.832 V
2.989 V
.651 V
R
19.3548 kΩ
19.7838 kΩ
19.3280 kΩ
18.6813 kΩ
16.275 kΩ
I-V Curve for Resistor #2
12
V - Voltage (Volts)
10
8
6
4
2
0
0
0.1
0.2
0.3
0.4
I - Amperage (mA)
Mean Resistor Value = 18.6846 kΩ
Actual Resistor Value = 19.7 kΩ
0.5
0.6
0.7
Forward Polarity Diode Circuit
Supply V
1
2
3
4
5
6
7
8
9
10
I
.33 mA
.98 mA
1.64 mA
2.31 mA
2.98 mA
3.65 mA
4.33 mA
5.00 mA
5.68 mA
6.36 mA
V
.523 V
.575 V
.600 V
.617 V
.629 V
.639 V
.647 V
.654 V
.660 V
.665 V
Forward I-V Curve for a Diode
7
6
I - Amperage (mA)
5
4
3
2
1
0
0.5
0.52
0.54
0.56
0.58
0.6
V - Voltage (Volts)
0.62
0.64
0.66
0.68
Reverse Polarity Diode Circuit
Supply V
1
2
3
4
5
6
7
8
9
10
I
0 mA
0 mA
0 mA
0 mA
0 mA
0 mA
0 mA
0 mA
0 mA
0 mA
V
-1.003 V
-2.003 V
-3.003 V
-4.003 V
-5.004 V
-6.004 V
-7.010 V
-8.010 V
-9.010 V
-10.010 V
Reverse I-V Curve of a Diode
I - Amperage (mA)
0.5
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
-0.5
V - Voltage (Volts)
● Conclusion
The resistor portion of the lab showed how to properly take voltage and current
measurements with the digital multimeter in a complete circuit. Also, by comparing the
voltage and amperage readings with the resistance measurement made by multimeter, the
digital multimeter was shown to be more accurate than computing the resistance values.
Finally, the experiment showed clearly the linear relationship of voltage and amperage to
resistance (V = IR).
The diode portion of the lab not only continued to teach proper measurement
taking techniques, but also showed the characteristics of a diode. In forward polarity, the
diode conducts current through it along with a small voltage drop. When the polarity is
reversed however, no current passes through and there is no voltage drop. This effect
allows the diode to only conduct current and voltage in one direction.
The experiment was fundamental in teaching how to record data and make
measurements with a digital multimeter, and also showed visually the characteristics of
two simple building blocks of electronic circuits.