Op-Amp Amplifier Lab: Building & Using an Oscilloscope in ECE 125, Lab Reports of Electrical and Electronics Engineering

Download Op-Amp Amplifier Lab: Building & Using an Oscilloscope in ECE 125 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! Lab #4, p. 1 ECE 125 Laboratory Project 4 Op-Amp Amplifier Circuits and Use of the Oscilloscope I. Purpose The purpose of this lab is to help you become familiar with op amps and with integrated circuits (ICs) in general.You will learn how to use a breadboard to create a circuit with an op amp and how to configure a dual power supply to produce positive and negative voltages referenced to a virtual ground.You will design and build an op-amp amplifier circuit and use it to amplify music from an iPod or Walkman-type CD player.You will also see how an oscilloscope is used to display time-varying signals. II. Lab Preparation A. Using an op amp, 10-kΩ resistor, and 100-kΩ resistor, design an inverting amplifier circuit with a gain of 10. Draw your circuit below. B. In the lab you’ll construct the amplifier circuit you just designed.You will use your breadboard, resistors, a 741 op-amp integrated circuit (included in your toolkit), and an Agilent E3620A Dual Power Supply. There are two 741 op-amp integrated circuits (ICs) in a small plastic bag in your toolkit. Remove one of the op amps, and inspect it closely. The circuit is embedded inside a small, rectangular black plastic block (which surrounds a “chip”) with eight metal legs, which are oriented in two columns. A package like this, with two columns of legs pointing downward, is called a Dual In-Line Package, or DIP. Because the 8-pin DIP is the smallest of this type of package it’s often called a minidip. Note that the DIP has a small circular indentation in one corner (or a small notch in the center of one side). If you orient the DIP with the indentation in the upper left corner (or the notch on the top side) and the legs facing downward, the legs are numbered as shown in Figure 1. Lab #4, p. 2 Metal leg1 2 3 4 5 6 7 8 Circular Indentation Figure 1. Profile sketch for the LM741 op amp in an 8-pin DIP. In order to use the op amp, we need to know what each of the eight legs are connected to inside the package. Inspecting the top of the op amp, you will see a stylized “N”. This is the trademark for National Semiconductor, one of the manufacturers of 741 op amps. You will also see the part number LM741CN. You can find information on the op amp by going to the National Semiconductor Web site (www.national.com) and searching on the key words 741 op amp. Once the Web site returns the results, look for the selection “741 – See the LM741 Product Folder”. Select this result. Now select or download the datasheet for the 741 op amp (you will want the datasheet for the regular 741 op amp, not any of the mil-aero datasheets). This 7-page data sheet contains a lot of information. Most of what we’re interested in is on the first page. Inspecting this first page, note that the 741 op amp comes in many different packages (metal can, DIP, and flatpak). The package in your tool box is an 8-pin DIP. Using the corresponding diagram on the datasheet, label the pin assignments for the 8 pins on Figure 2. You will recognize some of the assignments, like INVERTING INPUT, NONINVERTING INPUT, and OUTPUT, but not others, like V + and V – (these are power pins, as we shall see shortly), NC (“no connect”, an extra, unused pin), and OFFSET NULL (these are offset pins that we will not use). 1 2 3 4 5 6 7 8 Figure 2. Pin assigments for the LM741 op amp ( 8-pin DIP). C. Look at page 4 of the data sheet. This page contains the miniaturized, actual circuit implemented inside the DIP to produce the op amp (you can see the individual resistors and transistors in the circuit on the datasheet). How much do you think such a circuit should cost? D. Go back to the LM741 product folder page on the National Semiconductor Web site. Find and record the price of the LM741CN op amp. This is the op amp that you have in your