Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6 002 Electronic Circuits Fall 2005 Lab 4 Audio Playback System Handout F05 058 Introduction In this lab you will construct test and demonstrate the audio playback system which you designed in Homework 11 The lab consists of two parts Pre lab exercises and in lab exercises there are no Post lab exercises You should complete the Pre lab exercises in your lab notebook before coming to lab Then carry out the In lab exercises between November 28 and December 9 After completing the In lab exercises have a TA check your work and sign your lab notebook You may hand in your lab notebook for grading at that time Before asking to get checked off make sure you meet all the requirements in the checkoff list at the end of the In Lab Exercises Note that in addition to regular lab hours from November 28 to December 2 there will be staff available in the lab the following week December 5 through 9 for checkoff You will be notified as to the times in lecture and by email Reminder You must complete all of the labs Failure to do so will result in a deduction of one full grade in the class no exceptions Your lab notebook must be turned in with all Post Labs completed and you must be checked off for all the labs Pre Lab Exercises 4 1 Copy your design for the clock from Problem 1 of Homework 11 into your lab notebook Label all resistor and capacitor names and values 4 2 Next to your design for the clock copy the graph from Part E of Problem 1 of Homework 11 into your lab notebook You will use this information to determine whether the clock you construct during In Lab Exercise 4 2 works correctly 4 3 Copy your design for the digital to analog converter from Problem 2 of Homework 11 into your lab notebook Label all resistor names and values 4 4 Next to your design for the digital to analog converter make a table showing the expected converter output vDAC when each of the data bit input voltages is 5 V and the others are all 0 V Base the table on the actual resistor values used in your design Also note the expected value of the offset voltage vOFF required to center the converter You will use this information to determine whether the converter you construct during In Lab Exercise 4 4 works correctly 4 5 Copy your design for the low pass filter from Problem 3 of Homework 11 into your lab notebook Label all resistor and capacitor names and values 4 6 Next to your design for the low pass filter copy the graph from Part F of Problem 3 of Homework 11 into your lab notebook Also make a table showing the expected magnitude and phase of the filter output vLPF given a 2 V peak to peak sinusoidal input with a frequency of 4 kHz 8 kHz and 16 kHz Base the table on the actual resistor and capacitor values used in your design You will use this information to determine whether the filter you construct during In Lab Exercise 4 6 works correctly 4 7 Copy your design for the volume control stage from Problem 4 of Homework 11 into your lab notebook Label all resistor and capacitor names and values 4 8 Next to your design for the volume control stage make a table showing the expected magnitude and phase of the volume control stage output vOUT given a 2 V peak to peak sinusoidal input with a frequency of 10 Hz 100 Hz and 1 kHz Base the table on the actual resistor and capacitor values used in your design You will use this information to determine whether the amplifier you construct during In Lab Exercise 4 8 works correctly In lab Exercises The In lab exercises involve constructing and testing the individual functional blocks of the audio playback system and then demonstrating the operation of the system as a whole You will need to obtain the counter and memory printed circuit board PCB from the stockroom along with a small speaker Since there is a limited supply of circuit boards and speakers available make sure you return the memory board and the speaker when you are not using them The in lab exercises are organized so that you will construct and test one functional block at a time As each block is found to work properly you will connect it to those which already working Consequently you will alternately construct and test various parts of the audio playback system As you develop the system in this manner it is essential that you turn off the power to the protoboard before you make modifications to your system or begin any new construction Also check your wiring carefully before turning the power back on This will avoid damaging the components in the system and save you considerable debugging time Finally construct the functional blocks as compactly and neatly as possible In this spirit you should find it easiest to use the components to wire themselves together rather than using extra wires This will save you considerable construction time as well as considerable debugging time 4 1 If you are working in a group of two you should attach your two protoboards together This will simplify the circuit assembly by providing more wiring space To minimize wiring in this lab the counter and memory have already been assembled on a printedcircuit board On the back of this board are pins that will plug into the protoboards in the Lab Plug these pins into the protoboards so that each pin is inserted into a separate protoboard row Further locate the board so that there is considerable protoboard space on the side with the memory output data bits This will make connection to the board easiest For example locating the board towards the lower left corner of the protoboard may prove best The clock can then be constructed above the board while the digital toanalog converter the low pass filter and the buffer can be constructed to the right of the board Figure 1 shows the pin assignments for the printed circuit board The pins for the eight memory output data bits as well as the clock power and ground pins are on the right hand side You should connect the power pin to the 5 V power supply on the protoboard and the ground pin to ground on the protoboard 4 2 Following your design from Pre Lab Exercise 4 1 construct the clock using the 74HC14 inverter chip obtained earlier Figure 2 shows the pin assignments for the inverter chip Use any two of the inverters in the chip and leave the others unconnected Do not yet connect the clock output vCLK to the clock input of the counter Rather use one channel of the oscilloscope to observe the oscillator output
View Full Document
Unlocking...