Equipment:
1 Keithley Model 175 Digital Multimeter (DMM)
2 Pair of Banana to mini-grabber test leads
1 Prototype Bread Board
1 Agilent E3631A Triple Output DC Power Supply

Components:

• R1 - 9.1 Ohm Resistor
• R2 - 200 Ohm Resistor
• R3 - 4.3 K Ohm Resistor
• R4 - 6.8 K Ohm Resistor
• R5 - 750 K Ohm Resistor
• R6 - 3.9 M Ohm Resistor
• R7 - 8.2 M Ohm

• Determine the resistance values and tolerance of the given resistors by using the color code.
• Measure resistance with DMM and find the % error
• Calculate the total resistance and current in a simple DC series circuit
• Calculate the total power dissipated by each resistor in a simple DC series circuit
• Use the DMM to measure the voltage drops and current used in a simple DC series circuit
• Experience with the limits of a DMM
• Use your solderless prototype bread board
• Use a power supply.

1.- DC Circuit Measurements using the Keithley Model 175

Read about Keithley Model 175 and explain (step by step), with a block diagram how you would configure the Keithley Model 175 to measure

1. an unknown Resistance (R).

Label the block diagram as Figure 1a - DMM Measurement of Resistor.
2. an unknown DC Current (Idc).

Label the block diagram as Figure 1b - DMM Measurement of DC Current.
3. an unknown DC Voltage  (Vdc).

Label the block diagram as Figure 1c - DMM Measurement of DC Voltage.

2.- Solderless Bread Board Measurements

In this section you will try to understand the circuit connection of your solderless bread board.

1. Draw a schematic (circuit) of your solderless bread board.  Please also label the power supply line and ground line in the board.
2. Use the Ohms function of the Keithley Model 175 to help you verify that your schematic is correct. [Hint] If the resistance between two nodes in the board is 0 Ohms, that means that two nodes is connected.  If the resistance is too high (OverLimit), two nodes is not connected.

In this section you will learn about resistance measurements in detail using these steps:

1.  Use Resistor Color Code to determine the resistor ideal value (Nominal Value) and also theNominal  Tolerance  (how much the value can deviate from the nominal value).
2.  Use DMM to measure the actual value of the resistance
3.  Complete the Data Table 3 below using two steps describe above.
 

Resistor  Reference  Designator	Color   Code   Colors	Nominal   Resistance     (Ohms)	Tolerance  Percent   (Ohms)	Measured   Resistance      (Ohms)	Percent     Error      (%)
R1
R2
R3
R4
R5
R6
R7

                            Data Table 3

4.- DC Voltage and Current Measurements (Low Resistance)

In this section you will calculate and measure DC Voltage, DC Current and Power Consumption of two resistors in a simple DC circuit.

Draw a simple DC circuit that has two resistors (R3 and R4) connected in series with a DC Voltage Source (The reference designator for the voltage source is VS1).  R3 should be connected to the positive side of VS1.  Label this circuit as      Figure #1 - Low Resistance Series Circuit.

1. (PreLab H/W) Use Ohm's Law to analyze the circuit of Figure #1.  Use VS1=10Vdc.  Find the calculated (nominal) value of DC Voltage, DC Current and Power Consumption of R3 and R4.
2. Construct the circuit of Figure #1 using your solderless bread board.  Use Agilent E3631A Triple Output DC Power Supply as VS1 and set the voltage to 10Vdc.  Connect the RED lead from power supply to R3 and connect the ground (BLACK) lead to R4.  R3 and R4 is connected in series.  Use DMM (Keithley Model175) to measure DC Voltage and DC Current of R3 and R4.

NOTE: Consult the Keithley Model 175 operational manual for the proper directions on how to make voltage and current measurements.
3. Find the nominal/measured Power Consumption of R3 and R4 from nominal/measured DC Voltage and DC Current of R3 and R4.
4. Create and complete the Data Table 4 using following format:

5.- DC Voltage and Current Measurements (High Resistance)

In this section you will calculate and measure DC Voltage, DC Current and Power Consumption of two high value resistors in a simple DC circuit as in section 4.

Draw a simple DC circuit that has two resistors (R6 and R7) connected in series with a DC Voltage Source (The reference designator for the voltage source is VS2).  R6 should be connected to the positive side of VS2.  Label this circuit as      Figure #2 - High Resistance Series Circuit.

1. (PreLab H/W) Use Ohm's Law to analyze the circuit of Figure #2.  Use VS2=18Vdc.  Find the calculated (nominal) value of DC Voltage, DC Current and Power Consumption of R6 and R7.
2. Construct the circuit of Figure #2 using your solderless bread board.  Use Agilent E3631A Triple Output DC as VS2 and set the voltage to 18Vdc.  Connect the RED lead from power supply to R6 and connect the ground (BLACK) lead to R7.  R6 and R7 is connected in series.  Use DMM (Keithley Model175) to measure DC Voltage and DC Current of R6 and R7.

NOTE: Consult the Keithley Model 175 operational manual for the proper directions on how to make voltage and current measurements.
3. Find the nominal/measured Power Consumption of R6 and R7 from nominal/measured DC Voltage and DC Current of R6 and R7.
4. Create and complete the Data Table 5 using following format:

6.- Indirect DC Current Measurements

In this section you will calculate and measure DC Voltage directly from DMM and also measure DC Current and Power Consumption of three resistors indirectly  using a simple DC circuit as in section 4 and 5.

Redraw a simple DC circuit of Figure #2. Place R4 in series with R6 and R7.  Set voltage source (VS3) to 18Vdc.  Label this circuit as Figure #3 - High Resistance Series Circuit Modified for Indirect DC Current Measurement.

1. (PreLab H/W) Use Ohm's Law to analyze the circuit of Figure #3.  Use VS3=18Vdc.  Find the calculated (nominal) value of DC Voltage, DC Current and Power Consumption of R4, R6 and R7.
2. Construct the circuit of Figure #3 using your solderless bread board.  Use Agilent E3631A Triple Output DC Power Supply as VS3 and set the voltage to 18Vdc.  Connect the RED lead from power supply to R4 and connect the ground (BLACK) lead to R7.  R4, R6 and R7 is connected in series.  Use DMM (Keithley Model175) to measure DC Voltage ONLY of R4, R6 and R7.

 
3. Find the nominal/measured Current and Power Consumption of R4, R6 and R7 from nominal/measured DC Voltage of R4, R6 and R7.  [Hint] Use Ohm's Law to find DC Current from DC Voltage and Resistance value.
4. Create and complete the Data Table 6 using following format:

7. Input Resistance of the Keithley Model 175

You now have enough information to find the input resistance of the DMM.  Consult the DMM Data sheet and operating manual and use the "ideal dc model of a voltmeter" to find the input resistance.  Explain how you will find the input resistance in detail.  Be sure to use the appropriate circuit diagrams and show all the calculations.
 

8.  Conclusions

1. Compare the nominal results with the measured results of Data Table 4, Data Table5 and Data Table 6.  Explain any differences between the nominal and measured results on those Data Tables.
2. Explain how you would find the voltage drops in a highly resistive circuit when the DMM takes too much current from the circuit.