Department of Electronics and Mechanical Date:
ELEC 195 - Circuits Theory II
Experiment 6
VOLTAGE DIVIDER IN A SERIES RLC CIRCUIT
Objective:
The purpose of this lab is to calculate phasor voltages in a series RLC circuit using the voltage divider principle, to confirm those calculations by setting up the circuit on a breadboard and measuring the magnitude and phase of the voltage, and by simulating the circuit on PSpice.
Equipment:
1 4.7kW resistor
1 100pF capacitor
1 10 mH inductor
1 BNC / clip leads
2 High impedance oscilloscope probes
1 pair banana/clip leads
Breadboard
Fig. 1 Series RLC Circuit.
PROCEDURE:
1. Obtain the components for the circuit of Fig. 1, and measure and record their exact values.
R = ______C = ______L = ______
2. Using your measured values of R, L, and C, apply the voltage divider principle to determine the voltages, V2 and V3. Use V = 5 Vrms and f = 100 kHz. Show your calculations on the Calculations page. Express the voltages in polar form
V2 = ______V3 = ______
3. Connect the circuit of Fig. 1. Using the HP33120A Function Generator, apply a 5 V rms sine wave to the circuit, and set its frequency to 100 kHz. Use the DMM to measure the magnitude of the voltages V2 and V3. Use the oscilloscope to measure the phase angle of V2 and V3 with respect to the input voltage
Magnitude of V2 = ______Angle of V2 = ______
Magnitude of V3 = ______Angle of V3 = ______
4. Simulate the circuit of Fig. 1 using PSpice. Use the measured values of the components in the simulation.
5. For the ac source, use VSIN. Double click on the source, and set DC = 0, VOFF = 0, VAMPL = 5, FREQ = 100kHz, PHASE = 0.
6. Click on the SETUP icon, and from the selections that appear, click on the box to the left of the word Transient, and then click on the rectangle where the word Transient appears. Under Transient Analysis, set Print Step = 5ns, Final time = 20ms, No Print Delay = 10ms, and Step Ceiling = 10ns. Click OK, then Close.
7. Place a voltage marker at each of the three numbered nodes in Fig. 1. Assign a name to the file, save it, and then Simulate. After a few seconds, you should end up in PROBE, with a display of the three voltages plotted as a function of time. The display should contain exactly one cycle of each of the voltages.
8. Use the cursors to determine the maximum value of each of the voltages
V2 = ______V3 = ______
9. Use the cursors to determine the phase angle of each of the voltages with respect to the input voltage. To do this, measure td, the time between the start of the input sinusoid and the time when the output sinusoid crosses zero. Calculate the angle, q, as follows: q = (td/T) x 360o, where T is the period of the sine wave, 10ms for this waveform. Show calculations on the calculation page. Obtain a printout of the PROBE plot with the cursors placed at the first zero voltage point of each of the output voltages.
Angle of V2 = ______Angle of V3 = ______
10. Draw the vector diagram to find the impedance seen by the source