Name: Daniel Bernard
Partner: Matthew Engel
ECE 2006
Lab #01 Digital Multimeter
Performed: September 12, 2011
Due: September 19, 2011
Lab TA: Tiger Qian
1. Introduction and Background
The goal of this lab is to learn to use a digital multimeter to record voltage, current and resistance
in basic circuits, and calculate appropriate tolerances based upon the accuracy of the multimeter.
Apply Ohm’s law to measure voltage, current and resistance using resistors in series/parallel.
Resistance from the multimeter and wires should be ignored.
2. Procedure
2.1. Individual Resistors
2.1.1. Nominal Resistance
Using three 5% resistors with resistance of 2200Ω, 4700Ω and 6800Ω calculate their tolerance,
minimum, and maximum resistance, recording your data in Table 1.
2.1.2. Ohmmeter
Use the ohmmeter function on a digital multimeter to measure the resistance in ohms of the three
resistors individually. Calculate for each resistor the tolerance, minimum, and maximum
resistance, recording your data in Table 2.
2.1.3. Using Ohm’s Law to Calculate Resistance
Set up a DC power supply to output 10 V DC. Use the voltmeter function on a digital multimeter
to measure the output from the power supply after passing through the resistors individually. Set
up the circuit again such that the digital multimeter can be used to record current as an ammeter
and measure the current through the resistors. Calculate the resistance via the equation of Ohm’s
Law; 𝑉 = 𝐼𝑅. Record your data in Table 3.
2.2. Series Resistors
2.2.1. Nominal and Measured Resistance
Calculate the nominal equivalent resistance using the color code on the resistors and the
ohmmeter function on a digital multimeter, separately calculating tolerance, minimum and
maximum circuit resistance. Record your data in Table 4.
2.2.2. Using Ohm’s Law to Calculate Resistance
Use the digital multimeter as a voltmeter, and the DC power supply set to output 10 V DC.
Setting up the resistors in series, measure voltage through the circuit powered by the power
supply. Set up the circuit again with the ammeter function on the digital multimeter, and measure
the current. Calculate tolerances for voltage and current. Using Ohm’s law, calculate the
resistance, tolerance, minimum and maximum and record your data in Table 5.
2.3. Parallel Resistors
2.3.1. Nominal and Measured Resistance
Calculate the nominal equivalent resistance using the color code on the resistors and the
ohmmeter function on a digital multimeter, separately calculating tolerance, minimum and
maximum circuit resistance. Record your data in Table 6.
2.3.2. Using Ohm’s Law to Calculate Resistance
Use the digital multimeter as a voltmeter, and the DC power supply set to output 10 V DC.
Setting up the resistors in parallel, measure voltage through the circuit powered by the power
supply. Set up the circuit again with the ammeter function on the digital multimeter, and measure
the current. Calculate tolerances for voltage and current. Using Ohm’s law, calculate the
resistance, tolerance, minimum and maximum and record your data in Table 7.
2.4. Equipment List
o DC Power Supply
o Resistors (5% Tolerance 2200Ω, 4700Ω, 6800Ω)
o Digital Multimeter (with ammeter, ohmmeter and voltmeter settings)
3. Results
See attached sheet for Tables 1-7, displaying data from the previous sections.
3.1. Sample Calculations/Equations
Nominal Tolerance Calculation:
Example:
𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 ∗ 5% = 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒
2200Ω ∗ 5% = 110Ω
Minimum Calculation:
Example:
𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 − 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒 = 𝑀𝑖𝑛𝑖𝑚𝑢𝑚
2200Ω − 110Ω = 2090Ω
Maximum Calculation:
Example:
𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 + 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚
2200Ω + 110Ω = 2310Ω
Measured Tolerance Calculation:
OR
OR
Example:
𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 ∗ .1% + 2 𝑑𝑖𝑔𝑖𝑡𝑠 = 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 ∗ .3% + 2 𝑑𝑖𝑔𝑖𝑡𝑠 = 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒
𝑉𝑜𝑙𝑡𝑎𝑔𝑒 ∗ .03% + 2 𝑑𝑖𝑔𝑖𝑡𝑠 = 𝑇𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒
2199Ω ∗ .1% + 2 𝑑𝑖𝑔𝑖𝑡𝑠 = 2.201Ω
Ohm’s Law:
Example:
𝑉𝑜𝑙𝑡𝑎𝑔𝑒 = 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 ∗ 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒
9.951𝑉 / 4.528𝑚𝐴 = 2197Ω
4. Conclusions
The most accurate measurement technique was through use of the digital multimeter for
recording resistance, current, and voltage. In terms of convenience, if you did not have access to
the circuit, such as if you were to be viewing someone else’s circuit diagram, nominal resistance
based off the color codes would be the most convenient. However, if you had access to the full
circuit, using the multimeter would be far more accurate for making measurements.`