Equipment:
1 Keithley Model 175 Digital Multimeter (DMM)
2 Pair of Banana to mini-grabber test leads
1 Prototype Bread Board
1 BNC T Connector
1 Banana to BNC Adapter Plug
1 50 Ohm Load

Components:
RL 50 Ohm
R1 1.5 MOhm

Objectives:

• Determine input resistance of Keithley Model 175
• Determine input resistance of Keithley Model 178
• Determine input resistance of Tektronix Model 2213
• Verify maximum/minimum input voltage of HP8116A
• Use Tektronix Model 2213 to measure AC Voltage
• Determine the peak voltage values (Vp) for different periodic waveforms
• Determine the rms voltage values (Vrms) for different periodic waveforms
• Determine the average voltage values (Vavg) for different periodic waveforms
• Compare and explain the results obtained from DMM and analog oscilloscope for measurement of different periodic waveforms

(PreLab) A. Design

1. Design a series circuit that has a voltage source (Vs) and two resistors (R1 and RM).
2. RM represent input resistance of Keithley Model 175 / 178.
3. Draw this test circuit and annotate it as Figure #1.
4. Derive a general equation in terms of RM assuming the values of Vs, VM and R1 are known.
5. Label this equation - "Equation 1 - Equation for finding RM"

1. Construct the circuit of Figure #1.  Use Vs = 15Vdc and R1=1.5 M Ohm.
2. Use Voltmeter function of Keithley Model 175 to measure VM.
3. Measure Vs, R1 and VM as accurate as you could.
4. Use Equation 1 to find input resistance of Keithley 175 using measured values Vs, R1 and VM.
5. Repeat step 1 to 4 using voltmeter function of Keithley 178.
6. Find input resistance of Keithley 178.

(PreLab) A. Design

1. Design a series circuit that has a voltage source (Vs) and two resistors (R1 and Rscope).
2. Rscope represent the input resistance of Tektronix 2213.
3. Draw this test circuit and annotate it as Figure #2.
4. Derive a general equation in terms of Rscope assuming the values of Vs,Vscope  and R1 are known.
5. Label this equation - "Equation 2 - Equation for finding Rscope"

1. Construct the circuit of Figure #2.  Use Vs = 15Vdc.
2. Use Voltmeter function of Keithley Model 175 to measure Vs, and VR1.
3. Use Tektronix 2213 to measure DC voltage across Rcope.
4. Measure Vs, VR1 and Vscope as accurate as you could.
5. Use Equation 2 to find Rscope.

The concept of AC signal is introduced in this section.  Function generator (HP8116A) is used to produce AC voltage.  Three most common AC signals are sine wave, rectangular wave and triangular wave.  Oscilloscope is used to measure AC signals and  in this lab analog oscilloscope (Tektronix 2213) is used.

A. Setting up HP8116A

1. Read HP8116A manuals throughly.  The manual can be read HERE.
2. Set up HP 8116A to the folowing specifications.

POWER          1(ON)
MODE             NORM
WAVEFORM  depress a button that has sine wave above it.
FREQ               use the range and vernier switch to select 10 kHz
DTY                 50%
AMP                16.0 V
OFS                  0V
 
3. Connect the output of function generator to one end of a BNC Cable.
4. Depress the DISABLE button on the function generator panel.

1. Read Tektronix 2213 manual throughly.  The manual can be read HERE.
2. Read in detailed the section on how to measure AC Voltage.
3. Connect the the other end of BNC cable coming from the function generator to CH1 input of the oscilloscope.
4. If needed, adjust the trigger control to obtain a stable waveform.
5. Adjust CH1 VOLTS/DIV to display at least one complete sinewave of the signal on the screen.
6. Adjust SEC/DIV to display at least one complete cycle sinewave of the signal on the screen.
7. Measure and record the peak to peak voltage value of the waveform shown on the screen.
8. On the function generator, change AMP = 10.0 mV
9. Repeat step 4-7 above.
10. Put the measurement result in Data Table 3B - AC Voltage Measurement using Tektronix 2213.

1. Draw the function generator (HP8116A) with its output resistance(Rs) connected to the load (RL).  Output resistance of function generator can be found from the online-manual.  Set the load RL to be 50 Ohm.
2. Label this circuit Figure #3.
3. Derive a general equation to describe the peak to peak voltage across RL.  Label this Equation 3C.
4. Change AMP = 16.0 V on the function generator.
5. Construct Figure #3 and connect the input of function generator to CH1 of oscilloscope through a BNC cable.
6. Measure the peak to peak output voltage across RL.
7. Put the measurement result in Data Table 3B.

4. Meter Responses and Waveforms

(PreLab)  A. Calculation of Vpeak peak, Vrms and Vavg for different periodic waveforms

Show the formula on how to find the V peak to peak, Vrms and Vavg values for:

1. Sine wave
2. Triangle wave
3. Square Wave

Sketch the general waveform for each wave.
[Hint] Read textbook Chapter 5-6.

Given Vamplitude = 5.0 Vpeak and f = 1 KHz, find nominal values for those three waveforms.  Put all the calculated data in Data Table #4A.
 
 

	Vpp	Vp	Vrms	Vavg
Sine Wave
Triangle Wave
square wave

                        Data Table #4A

In this section you are asked to measure Vpp, Vp, Vrms and Vavg of periodic waveforms using the combination of three instrument: Keithley 175, Keithley 178 and analog oscilloscope (Tektronix 2213).  Read the instruments manual on AC Voltage measurement to have a better understanding of their measurement capabilities.
1. Set up HP 8116A to the folowing specifications.
        POWER           1(ON)
        MODE             NORM
        WAVEFORM  depress a button that has a SINE wave on it.
        FREQ               use the range and vernier switch to select 1 kHz
        DTY                 50%
        AMP                5.0 V
        OFS                  0V
1. Depress the DISABLE button on the function generator panel.
2. Set  Tektronix 2213, Keithley Model 175 and Keithley Model 178 in  a way so that the combination of those equipment can measure Vpp, Vp, Vrms and Vavg output of the function generator ALL AT THE SAME TIME.  Put the measured data in Data Table 4B.
3. Change the waveform setting of the function generator to TRIANGULAR WAVE.  Repeat step 3.
4. Change the waveform setting of the function generator to SQUARE WAVE.  Repeat step 3.
5. Analyze the data of Data Table 2 and answer these questions:
1. Which instrument measures the average value of an input waveform but is calibrated to read the RMS value of that waveform. (Hint: Check the manual of each instrument on AC measurement to find this information.)
2. Identify which instrument is best suited to measure rms value at this frequency.

1. Compare the measured input resistances for Keithley 175, Keithley 178 and Tektronix 2213 to the published input resistances obtained from the instrument's manuals.
2. Is it important for us to know the values of the  instrument's input resistances that we are using in the lab?  Explain.
3. Compare Data Table 4A and Data Table 4B.  Explain any differences.