EE 100 Lab 4: Exploring RLC Circuits and Filter Design, Lab Reports of Electrical and Electronics Engineering

Download EE 100 Lab 4: Exploring RLC Circuits and Filter Design and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! EE 100 – Electrical Engineering Concepts I Lab 4 Revision 10/01 Name: ___________________________ Partner: ___________________________ Date: ___________ TA: ___________________________ RC Circuits Filters EE100 Lab 4 Grading Sheet Lab Grade: _________ (90 maximum) Presentation Grade: _________ (10 maximum) (organization, clarity, neatness) Total: _________ (100 maximum) Grader’s Comments: Hand in all lab and work sheets, either stapled securely or in a folder. EE 100 Lab 4 Page 3 Fig. 4-3 The time constant of the system is also the amount of time required for the system to reach %2.63 1 1 =⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − e of its stable state after a change. In this circuit, it can be measured on either the rising edge or falling edge of VCA. You will be using the horizontal scale to measure the time needed for the capacitor output to equal 63% of 4 volts. You may want to view Ch. A2 only for this part of the exercise, although it’s not a requirement. If you didn’t already, adjust the FG to make the maximum capacitor voltage exactly 4 Vp-p. Measure the time for the capacitor voltage to rise by 53.2)4)(632.0( = V from its minimum level. Note that, for greater accuracy, you can change the line thickness of your signal plots and cursors under the “Timing” pull down menu. τmeasured = ______________ From this value, calculate the capacitance: Ccalculate = ______________ Cnominal = 1 uF % Error = ______________ 1.5.3 Lowpass Filter Frequency Response Change the circuit of Figure 4-1 to use a 1 K resistor and a 0.1 uF (#9109F) capacitor. We will input a 1 V 0-peak sinusoid into the filter and measure frequency and phase response of the circuit. NOTE: Make sure you change the components to these new values! The break frequency for this filter should be RC fb π2 1= Given your new values for R and C, calculate what bf should be for this filter. bf = _____________ Hz Now test the filter to see if it behaves as expected. Input a 1 Volt 0-peak sinusoid over a frequency range from bf01.0 to bf100 . Use the filter plotting sheets provided in lab to record your data. Measuring amplitude variation is pretty easy on the oscilloscope; measuring phase difference as a bit more involved. The easiest way to measure a phase shift is to place the vertical o-scope Page 4 Lab 4 EE100 cursors on the zero-crossings of the two signals, and read off the time difference t∆ between the two crossings. Then, the phase difference in degrees is simply tf ∆= 360θ . After lab, calculate the theoretical values for the magnitude and phase of the filter response and comment on how well the filter followed the theory. Make bode plots of the filter magnitude and phase response to hand in with your lab. 1.5.4 High Pass Filter Swapping the positions of the resistor and capacitor used in the last circuit should yield a first order high pass filter with the same break frequency. Fill out a second filter analysis sheet for this filter, and comment on how well the filter follows theory. Make bode plots of the filter magnitude and phase response to hand in with your lab. 1.5.5 Inductive Low Pass Filter Build the circuit of Figure 4-4 using a 10 mH inductor and a 1 k resistor. Fig 4-4 This low pass filter should have a break frequency of L R fb π2 = . Given your new values for R and L, calculate what bf should be for this filter. bf = _____________ Hz Now test the filter to see if it behaves as expected. Input a 1 Volt 0-peak sinusoid over a frequency range from bf01.0 to bf100 . Use the filter plotting sheets provided in lab to record your filter response and comment on how well the filter followed the theory. Make bode plots of the filter magnitude and phase response to hand in with your lab. 1.5.6 Bandpass Filter Using a capacitor and an inductor, we can make a bandpass filter. Construct the circuit shown in Figure 4-5. Fig 4-5 EE 100 Lab 4 Page 5 This should be a resonant bandpass filter with center frequency LC f π2 1 0 = . The sharpness, or quality, of the filter is measured by R Lf Qs 02π= . Compute these values for the circuit of Figure 4-5. 0f = ____________ Hz sQ = ____________ Now test the filter to see if it behaves as expected. Input a 1 Volt 0-peak sinusoid over a frequency range from bf01.0 to bf100 . Use the filter plotting sheets provided in lab to record your data. What is the bandwidth of your filter? That is, what is the distance from the lower –3 dB point to the highest –3 dB point? (This is where the filter response is 0.707 volts 0-peak.) If I wanted a sharper bandpass filter at the same center frequency, what component(s) would I adjust and in which direction? Make bode plots of the filter magnitude and phase response to hand in with your lab.