Mini PCB Input Sensor and Display Circuits A Major Qualifying Project Report submitted to the Faculty of the Worcester Polytechnic Institute in partial fulfillment of the requirements for the Degree of Bachelor of Science By _______________________ Ian Schwartz _______________________ Lena Dagher _______________________ Chris Thomson _______________________ Renee Walker Submitted to: _______________________ Dr. John McNeill, Advisor Abstract The objective of this MQP was to use analog and other design techniques to build a circuit using one of Analog Device’s new Integrated Circuits. After much thought, research, and collaboration, the project chosen was the “Mini PCB Input Sensor and Display Circuits”. This project has two parts: the first being a small, inexpensive, and portable circuit designed to be distributed to high school seniors who attend WPI’s ECE undergraduate recruitment open houses. The second phase is a more complex version of the portable circuit, and would allow the user to connect to a PC via USB and display the output of the various sensors on a computer monitor. This paper guides the reader through the design process as seen through the eyes of the designers, detailing the unique processes considered to reach the final outcome. 1 Authorship The completion of this Major Qualifying Project involved a significant amount of time and dedication. This report represents a collaboration of ideas from all team members involved. Each aspect of the project was divided amongst the team members. Lena Dagher was responsible for the research and design of the temperature circuit. Christopher Thomson concentrated on the research and design of the IR pulse circuit. Ian Schwartz focused on the design of the electrocardiogram (ECG) circuit. Renee Walker contributed greatly to the design and implementation of the digital interface. The separation of these tasks allowed us to specialize our work to increase productivity. However, the success of this project was dependant on the collaboration of each team member in order to tie all the circuits together and design of the Mini Input Sensor Board. 2 Table of Contents Abstract ........................................................................................................................................... 1 Authorship ...................................................................................................................................... 2 Figures ............................................................................................................................................. 5 Tables .............................................................................................................................................. 8 Equations ........................................................................................................................................ 9 Executive Summary ....................................................................................................................... 10 Acknowledgments ......................................................................................................................... 13 Introduction .................................................................................................................................. 14 1 Background ................................................................................................................................ 15 2 Brainstorming Applications ........................................................................................................ 16 2.1 Potential Applications ......................................................................................................... 16 2.1.1 Home Appliance Power Monitor and Controller System ............................................. 16 2.1.2 Control Feedback Application ...................................................................................... 19 2.1.3 Motion-Controlled TV Remote ..................................................................................... 22 2.1.4 Magnetically-Controlled Axis Meter............................................................................. 24 2.1.5 Laser Microphone Application ..................................................................................... 29 2.1.6 LED Travel Game Set ..................................................................................................... 32 2.1.7 Mini PCB Input Sensor and Display Circuit ................................................................... 35 2.2 Choice of Application .......................................................................................................... 37 2.2.1 Discussion of Potential Circuit Options ........................................................................ 37 2.2.2 Plan of Attack ................................................................................................................ 39 3 Design Details ............................................................................................................................. 43 3.1 Design of Circuit Commonalties .......................................................................................... 43 3.1.1 Power Supply ................................................................................................................ 43 3.1.2 Automatic Power Switch .............................................................................................. 47 3.2 Skin Resistance .................................................................................................................... 49 3.2.1 Background Research ................................................................................................... 49 3.2.2 Experimentation and Design ........................................................................................ 50 3.2.3 Reason for Rejection .................................................................................................... 53 3.3 Temperature Circuit ............................................................................................................ 54 3.3.1 Main Goal of Temperature Circuit ................................................................................ 54 3.3.2 Background Research ................................................................................................... 56 3.3.3 Difficulties ..................................................................................................................... 58 3.3.4 Progression of Design: Measurements and Results ..................................................... 59 3.3.5 Final Circuit Design ....................................................................................................... 61 3 3.3.6 Component Selection ................................................................................................... 62 3.4 Pulse Circuit ......................................................................................................................... 63 3.4.1 Background Research ................................................................................................... 63 3.4.2 Circuit Design ................................................................................................................ 74 3.4.3 Difficulties ..................................................................................................................... 90 3.4.4 Component Selection ................................................................................................... 96 3.4.5 Measurement and Results ............................................................................................ 97 3.5 Electrocardiogram (ECG) ................................................................................................... 101 3.5.1 Background Research ................................................................................................. 101 3.5.2 Progression of Design: Measurement and Results .................................................... 103 3.5.3 Final Circuit Design ..................................................................................................... 146 3.5.4 Component Selection ................................................................................................. 151 3.6 Digital Interface ................................................................................................................. 152 3.6.1 Selection of Components ........................................................................................... 152 3.6.2 Digital Design .............................................................................................................. 156 3.6.3 Measurement and Results .......................................................................................... 163 4 Final Board Design ................................................................................................................... 172 4.1 Simple Board ..................................................................................................................... 172 4.1.1 Circuits Chosen for Simple Board ............................................................................... 172 4.1.2 Final Simple Board ...................................................................................................... 173 4.2 Complex Board .................................................................................................................. 174 4.2.1