ELEC 242 Lab

Experiment 8.2

Dynamic Performance

Part 1: Step Response



Step 1:

 Remove any weights from the hook.

Step 2:

 Replace with a 220k ohm resistor.

Step 3:

 Load the "Step Response" Labview program. Set the Duration to 2.0 sec and the Amplitude to 3.5 V.

Step 4:

 Run the program and print the response.

Step 5:

 Repeat the measurement for each of the values of used previously. Sketch each response and make a printout for = 4.7M.

Because of the increasing overshoot as the gain is increased, it will be necessary to reduce the amplitude as is increased. Here are some suggested values:

Amplitude
220k 3.5
470k 3
1M 3
2.2M 2
4.7M 1

Part 2: Frequency Response



Step 1:

 Connect A/D input 4 (pin 5 on the interface board socket strip) to (pin 11 on the socket strip).

Step 2:

 Load the "Frequency Response" Labview program. Set the parameters as follows:
  • Flo=0.5 Hz
  • Fhi=5.0 Hz
  • Nsteps=20
  • Amplitude=2 V
  • Magnitude Scale: dB
  • Frequency Scale: Log

Run the program for each of the values of used in previous measurements. As in the case of the step response, it will be necessary to reduce the amplitude as is increased. Here are suggested values.

Amplitude
220k 2.0
470k 1.0
1M 0.5
2.2M 0.2
4.7M 0.1


Step 3:

 For the underdamped cases, estimate and Q from the frequency response.

Question 3:

 Based on the analysis in the Background section (and performed in class) summarize the expected behavior of the system dyanmics as a function of summing amplifier gain A . Is this behavior reflected in your observations?