Lab 4 SIMPLE RC AND RL CIRCUITS Foundation Electronics Michael Johnson Simple RC and RL Circuits OBJECTIVE 1. Examine the transient behaviour of Resistor-Capacitor (RC) and Resistor-Inductor (RL) networks. 2. To investigate the charging and discharging of a capacitor. 3. To investigate the electromagnetic effect in an inductor. 4. To determine the existence of a particular time constant associated with RC networks. EQUIPMENT The following equipment will be required for this lab: - 1. Function Generator 2. Breadboard 3. Various Resistors, Capacitor and Inductor 4. Oscilloscope 5. BNC Cables/Leads Your breadboard circuits should look something like this when built: - kHz DJUSTMENT PICTO-BOARDB 503 POWER 0 FREQ AMP 1.0 FUNCTION GENERATOR 222 חר ח DE UNCED PUSHBUTTONS PB2 +5 wwwww BNC J1 LOGIC +V SWITCHES SHELL S1 S2 S3 S4 S5 S6 S7 S8 wwwww. wwwwwwwwwwwwwww ********** wwwww.wwwwww******www POT W R2 SPDT SWITCHES 13-15V 13-15V O CMOS LOW LOGIC INDICATORS 80 SPEAKER $10 SHELL O BNC J2 THEORY At the start of this lab, we will give you a brief tutorial on how to use the FUNCTION GENERATOR and the OSCILLOSCOPE to create and measure/view AC signals on the breadboard. PROCEDURE Part 1 - RC Circuit Consider the following RC circuit, shown in Figure 1: - Vin ( i(t) OV 10ΚΩ VA(t) R Figure 1-Simple RC Circuit C vc(t) 1nF . For the Function Generator, Vin(t), use the following settings to create a SQUARE wave to power the circuit: · Frequency: 15.9kHz Wave Output: Square [Period: T = 1/f] [Duty Cycle: 50%] Amplitude: 1V Offset: 0.5V [Vpp] [Vdc] . For this input square wave, calculate the period, T, (using the formula T 1/f, measured in seconds). Also determine Ton ("on" time) and Toff ("off" time), if the square wave has a 50% Duty Cycle [50% on, 50% off]. = • • Display Vin(t) and VA(t) on the Oscilloscope using two sets of scope leads. Make sure to display Vin(t) using Channel 1 and VA(t) using Channel 2. Take a picture of the front of the oscilloscope. Include your Student ID card in the image to show that it is your own, original work. The image should look something similar to what is shown in Figure 2- TELEDYNE LECROY SEOP =15.9011KHz CH1200mV CH2 200mV M 5.00ps CH1168mU M Pos:31.60ps Figure 2 - Example Oscilloscope Output for Figure 1 (Yellow = CH1, Blue = CH2) • . SKETCH this waveform into the Results section of your lab report for this part of the lab. Make sure to label the value(s) on the X (time) and Y (voltage) axes for the signals. Measure the periodic time, T, the On time, Ton, and the Off time, Toff, from the oscilloscope traces. . Calculate the maximum value which the voltage, vc(t), can reach for the given circuit. • Measure this maximum value for the voltage, vc(t), using the oscilloscope traces. Tabulate and compare these two values in the Results section of your lab report for this part of the lab. • Calculate the value of the TIME CONSTANT, t, for the circuit. Remember, t = RC for an RC circuit. • Measure the time at which the output waveform (CH2) reaches 63% of it's final output. This is the measured time constant, t, for this circuit. Again, tabulate and compare these two values in the results section of your lab report for this part of the lab. • Change the FREQUENCY of the input square wave, Vin(t), to be 1.59kHz. • • Take a picture of the new waveforms displayed on the front of the oscilloscope. SKETCH these new waveform(s) into the Results section of your lab report for this part of the lab. Again, make sure to label the value(s) on the X (time) and Y (voltage) axes for the signals. . Change the FREQUENCY of the input square wave, Vin(t), to be 159.0kHz. • • Take a picture of the new waveforms displayed on the front of the oscilloscope. SKETCH these new waveform(s) into the Results section of your lab report for this part of the lab. Again, make sure to label the value(s) on the X (time) and Y (voltage) axes for the signals. • Upload all three images of the oscilloscope waveforms along with the electronic version of your lab report to Brightspace. Sketch all three sets of waveforms into the results section of Part 1 of your lab report for this lab. Part 2 - RL Circuit Next, consider the comparable RL circuit, shown in Figure 3: - Vin ( i(t) 10ΚΩ OV R Figure 3-Simple RC Circuit L VA(t) 100mH 000 V₁(t) • For the Function Generator, Vin(t), we will use the exact same settings as we did in Part 1 to create the same SQUARE Iwave to power the circuit. All you should really need to do is change the frequency back to 15.9kHz. Frequency: 15.9kHz Wave Output: Square Amplitude: 1V Offset: 0.5V [Period: T = 1/f] [Duty Cycle: 50%] [Vpp] [Vdc] The calculations for T, Ton and Toff from the first part should all be the same and equally applicable here for Part 2 as well, if the square wave still has a 50% Duty Cycle [50% on, 50% off].