Experiment 1.A. Working with Lab Equipment. ECEN 2270 Electronics Design Laboratory 1

Transcription

1 .A Working with Lab Equipment Electronics Design Laboratory 1

2 1.A.0 1.A A.4 Procedures Turn in your Pre Lab before doing anything else Setup the lab waveform generator to output desired test waveforms, and setup the lab oscilloscope to show the waveforms and measure waveform parameters Setup the lab power supply and the multimeter to measure resistances, generate and measure dc voltages and currents Note: Before you start working on the lab tasks, read the Lab report guidelines, and create a Word document for your Lab Report so you can enter text, data, diagrams, analyses, simulations, and results as you work through the lab. The objective is to have the lab report essentially completed by the time you finish the lab. It is a good idea to keep back copies of the lab report as your work in progress. After you complete the lab you will submit the lab report for grading via D2L. Electronics Design Laboratory 2

3 A.1.a Square Wave Generation Use a BNC cable to connect the output of the waveform generator to Channel 1 input of the oscilloscope. Setup the waveform generator to produce a periodic pulsating waveform (square wave) using the values in Table 1 Parameter Minimum Voltage (V min ) Maximum Voltage (V max ) Frequency (f) A.1.b Square Wave Capture Value 0 V 2 V 1 khz Duty Ratio (D) 50% Table 1 Square wave parameters Setup the oscilloscope to display a few periods of the waveform and to measure amplitude, frequency and duty ratio on screen. Capture and save the waveform on a USB drive (or using an alternative method suggested by TA) Include a screen capture of the waveform in your lab report. Be sure to describe the waveform in words, pointing to the screenshot as a reference. Figure 1 Example square wave capture Electronics Design Laboratory 3

4 A.2 Periodic Pulsating Waveform Setup the waveform generator to produce a periodic pulsating waveform using the parameters in Table 2 Setup the oscilloscope to display and measure important features of the pulsating waveform, as shown in the Figure 2 4 In the report, include the oscilloscope screenshots, and describe the waveform characteristics in words, with reference to the screenshots. What is the duty cycle D? Parameter Value Minimum Voltage (V min ) 0 V Maximum Voltage (V max ) 2 V Frequency (f) 1 khz Pulse Width (t on ) 20 μs Rise Time (t r ) 100 ns Fall Time (t f ) 300 ns Table 1 PPW parameters Figure 2 Zoomed out view Figure 3 Rising edge Figure 4 Falling edge Electronics Design Laboratory 4

5 A.3 Burst of Pulses Setup the waveform generator to produce a burst of three pulses shown in Figure 5. In the report, describe how you set up the waveform generator and the oscilloscope, include the captured oscilloscope screenshot, and describe the waveform characteristics in words, with reference to the screenshot. Figure 5 A burst of pulses Electronics Design Laboratory 5

6 Stop! No need to rush through Parts A1 A3 as quickly as possible Make sure each Team member is familiar with the waveform generator and the scope functions. Each Team member must be able to perform Parts A1 A3 quickly and independently. Take some time to play with the scope settings, most of which can be done in multiple ways: through touch screen or hard buttons, in particular: Trigger settings Vertical settings for a selected channel Horizontal settings Measurements and cursors Resist the urge to press on the auto scale button Electronics Design Laboratory 6

7 A.4.a Resistance Select two resistors with values of approximately R 1nom = 100 and R 2nom = 200 from your lab parts kit. Measure actual resistance values R 1 and R 2 using the multimeter. Compare the measures values, the value expected from the resistor color codes, the error between these two values, and the stated tolerance. A.4.b Voltage and Current Setup the power supply to produce V LIMIT = 12 V output voltage, with a current limit of I LIMIT = 0.1 A. Repeat the following sub parts for both R 1 and R 2. Connect the power supply to the resistor and measure the dc voltage V DC across the resistor and the dc current I DC through the resistor using a multimeter Calculate the resistors value from these measurements. Comment on any errors. Find power (P 1 or P 2 ) dissipated on the resistor. Sketch and label a circuit diagram to show how the power supply and the resistor are connected. Use a voltage source symbol or a current source symbol for the power supply, as appropriate. On a plot of V DC as a function of I DC, plot the load lines for both R 1 and R 2. Include lines for V LIMIT and I LIMIT. Preferably this will be done in MATLAB outside of lab hours. Electronics Design Laboratory 7

8 A.5.a Simple RC Circuit Characterization Select a resistor of approximately 1k from your lab kit, and a capacitor of approximately 10nF. Note the values chosen in your lab report. On your breadboard, design the circuit in Fig 6. This is circuit implements a first order low pass filter. R + + The input, V in, should be applied using your function generator. Use the following parameters to begin with V in C V out Sine wave, 1kHz frequency. 5Vpkpk, 2.5V offset, High Z output mode. Figure 6 Low Pass Filter Using two scope probes display both the input voltage, V in, and the output voltage, V out, on your oscilloscope. Using your scope measure and record the input voltage amplitude and the output voltage amplitude. Sweeping the frequency from 1kHz to 1MHz, record the above values for at least 20 data points. Use may use the Matlab command logspace(3,6,20) to generate an appropriate list of frequency values to use. Include the values in a table at the end of your report. Electronics Design Laboratory 8

9 A.5.b Simple RC Circuit Characterization Plot in Matlab the measured data points using linear axes for voltage and frequency. There should be two sets of data on this plot. Use blue circles for the input voltage points, and red x s for the output voltage data points. Does the value of the input voltage amplitude change? If so, why? Calculate the gain of your low pass filter, A LP, at each frequency using the formula below. In this formula V in is the measured input voltage amplitude and V out is the measured output voltage amplitude. A LP Plot A LP vs. frequency, using a logarithmic scale for both axes (this can be done in Matlab using the plotting command loglog ). Why is this circuit called a low pass filter? V V out in Electronics Design Laboratory 9