School of Engineering
ENGN 2218 Electronic Systems and Design
HLab02: Op-amp Schmitt Trigger
“In this lab, we will investigate Schmitt trigger comparator circuit. ”
“The pre-lab reading will help you make sense of what you are about to do in the lab. The lab tasks and evaluation and review questions will form the basis of your lab report. See course document on how to write the lab report.”
1.0 Lab Learning Outcomes
After completing this lab, students will be able to:1. Compare the input and output waveforms for a comparator and Schmitt trigger circuits.
2. Use an oscilloscope to plot the transfer curve for a comparator, including one with hysteresis. 1.1 Pre-Lab Reading
1. Lectures 10, 11.
2. Problem Set 04.
3. Op-amp datasheet.
1.2 Lab Tasks
1. From lab handout: 22 Comparators and Schmitt Triggers, Procedure: 1 − 8.
1.3 Evaluation and Review Questions
1. From lab handout: 22 Comparators and Schmitt Triggers, Evaluation & Review Questions: 1 − 5.
Semester 1
page 1
ANU
School of Engineering
1.4 Lab Instructions
1. From the lab components kit, find and examine the op-amp. Identify the op-amp terminals.
2. When wiring up the op-amp circuits, use the breadboard rails to establish +Vcc , −Vcc and ground respectively for the circuit. Apply the sinusoidal input directly to the circuit using a cable with connecting clips. Ask the tutor if you are unsure about this.
1.5 Theory
1. The computed values required in this lab are very easy to calculate. Hence no hints are provided. 1.6 Examples of most common HLab02 mistakes
1. Everything is wired correctly etc but there is no output: Make sure the offset voltage is
NOT (accidentally) enabled on your function generators.
2. Op-amp terminals not correctly identified. The op-amp chip may get damaged if used in a circuit with incorrect connections. Ask the tutor to check your circuit and replace the op-amp if necessary.
3. Dangerous!: Electrolytic capacitor