ECE 270 Lab Verification / Evaluation Form Experiment 2 Evaluation: IMPORTANT! You must complete this experiment during your scheduled lab period. All work for this experiment must be demonstrated to and verified by your lab instructor before the end of your scheduled lab period. STEP DESCRIPTION MAX SCORE 1 Installation and Test of Potentiometer 1 2 LED Voltage and Current Measurements Using the DMM 6 3 Gate Voltage and Current Measurements Using the DMM 6 4 Timing Measurements Using the Oscilloscope 8 5 Thought Questions 4 TOTAL 25 Signature of Evaluator: ________________________________________________________ Academic Honesty Statement: IMPORTANT! Please carefully read and sign the Academic Honesty Statement, below. You will not receive credit for this lab experiment unless this statement is signed in the presence of your lab instructor. “In signing this statement, I hereby certify that the work on this experiment is my own and that I have not copied the work of any other student (past or present) while completing this experiment. I understand that if I fail to honor this agreement, I will receive a score of ZERO for this experiment and be subject to possible disciplinary action.” Printed Name: _____________________ Class No. __ __ __ __ - __ Signature: ____________________________________ Date: _______ECE 270 - Experiment 2 Purdue IM:PACT Little Bits Lab Manual -1- © 2013 by D. G. Meyer Measurement of Gate Electrical and Timing Characteristics Instructional Objectives: • To become familiar with the functions and capabilities of the digital multimeter and the digital oscilloscope • To learn how to make voltage and current measurements using the digital multimeter • To learn how to measure logic signal transition times and propagation delays using the digital oscilloscope Prelab Preparation: • Read this document in its entirety Lecture/Demonstration: Your lab instructor will give a brief presentation that includes the following: • A demonstration of how to measure voltages and currents using the digital multimeter (DMM) at your lab station • An explanation of how to read resistor color codes • An explanation of the difference between a resistor LED and a non-resistor LED • A demonstration of how to install the 20 MHz oscillator module on your breadboard • A demonstration of how to install the 10K ohm potentiometer (“pot”) on your breadboard • A demonstration of how to measure rise and fall times of a logic gate using the oscilloscope • A demonstration of how to measure rise and fall propagation delays using the oscilloscope Step (1): Installation and Test of Potentiometer Connect the 10K ohm potentiometer to +5 VDC and ground, as shown, and measure the voltage on the “wiper” (middle terminal) with respect to ground using the Digital Multimeter (DMM). Verify that you measure 0 volts when the potentiometer is fully counter-clockwise, and measure close to 5.0 volts when the potentiometer is fully clockwise. Trouble-Shooting Tip: When making measurements using the DMM, make sure the probes are connected to the correct DMM inputs (note that different pairs of inputs are used for measuring voltage and current) and that the function selector dial is set to measure DIRECT CURRENT (D.C.) voltage or current, respectively.ECE 270 - Experiment 2 Purdue IM:PACT Little Bits Lab Manual -2- © 2013 by D. G. Meyer Step (2): LED Voltage and Current Measurements Using the DMM Perform the following exercises and record your results. (a) Connect a GREEN non-resistor LED and a YELLOW non-resistor LED in series with 1K ohm resistors (color bands brown-black-red) as illustrated below. Note that the 1K resistor on the left should be connected between +5VDC and the anode (long lead) of the GREEN LED (the cathode of which should be connected to ground), while the 1K resistor on the right should be connected between ground and the cathode (short lead) of the YELLOW LED (the anode of which should be connected to +5 VDC). Measure the forward voltage VLED across each LED and record your results in the space provided. Then, remove the “jumper wires” between the resistors and LEDs and measure the forward current ILED of each LED, and record your results in the space provided. (b) Using the DMM, measure the actual impedance of a “brown-black-red” (1K ohm) resistor. Rmeasured = _________________ ohms (c) Calculate ILED based on the following equation (Ohm’s law): (5.0 – VLED)/Rmeasured ILED (calculated) = _______________ How does the calculated value of ILED compare with the value measured above? _______________________________________________________________________ _______________________________________________________________________ VLED (green) = _________ V ILED (green) = _________ mA VLED (yellow) = _________ V ILED (yellow) = _________ mA YELLOW LED GREEN LED 1K ohm ResistorsECE 270 - Experiment 2 Purdue IM:PACT Little Bits Lab Manual -3- © 2013 by D. G. Meyer Step (3): Gate Voltage and Current Measurements Using the DMM Perform the following exercises and record your results. (a) Disconnect the resistors (used in the previous step) from +5 VDC and ground (for the GREEN and YELLOW LEDs, respectively). Connect both resistors to pin 2 of the 74HC04 (hex inverter). Connect pin 1 of the 74HC04 to a DIP switch. Verify that the green LED illuminates when the switch input is LOW, and that the yellow LED illuminates when the switch input is HIGH. (b) Using this configuration, measure VOH, IOH, VOL, and IOL of the 74HC04 using the DMM. Compare the measured values with those given in the data sheet appearing on page 98 (Table 3-3) of the course text. Are there any notable differences? (c) Remove the non-resistor (GREEN and YELLOW) LEDs and resistors from your breadboard and install a 74HC14 (hex inverter with Schmitt trigger inputs); leave the 74HC04 (already in place) on the board, but connect pin 1 of both chips to the wiper of the potentiometer. Connect the DMM between the wiper of the potentiometer and ground in order to measure the input voltage. Connect pin 2 of each chip to the