Stephen Joo and Daniel Kattan April 16, 2010 ECE 002, Group 8

 We, Stephen Joo and Daniel Kattan are Group 8 of ECE 002. Throughout the semester, we have learned many things with each lab. We have faced many challenges and through them learned a lot. The different projects in ECE 2 gave us a taste of what’s to come in the next few semesters of engineering here at GW.

 Lab introduced different types of sensors  Taught how to test different sensors to determine optimal range of use as well as how to write program using those sensors Sensors tested: - light sensor - sonar sensor - optical rangefinder - touch sensor These were critical in next project, creating and programming an elevator.

 Provided fairly stable results over the entire spectrum  Useful for wide range of applications  Can reliably detect differences between not only white and black but also different scales of gray  Can be used to detect subtle changes in lighting, not just shift from black to white

 Results somewhat unpleasant because only accurate within certain range  According to results, sensor goes haywire and gives extreme values or values that are indiscernible from those around them (i.e. nonlinear) just outside of small normal range  Makes this sensor ill-suited to all but very crude applications.

 Results extremely accurate and precise  When we made graph based on data, sensor provided extremely linear graph.  Sensor is ideal for any application for measuring distances since it provides consistent and stable results at any certain distance.

 Results from these tests greatly influenced which sensors to use for elevator project  We decided to use Because sonar sensor had such linear and stable results, it as primary sensor for elevator  Rangefinder had varied results and felt it would be unreliable for use in project  Didn’t use light sensor either because it had little use in our design

 Unique design: using only one sensor, which is sonar sensor  Elevator call buttons were start and stop buttons on Handyboard  Group felt we would have a simpler code by using only one sensor  While somewhat true, the code became more complicated to write than initially anticipated Trials: - rewrote code several times until got it working properly. - had to fine tune timing of the elevator car.

Design: - simple and easy to construct and was reliable in its operation - streamlined stopping to simply turning off motor - enough friction was built into raising/lowering mechanism to ensure elevator stayed in place whenever motor was off

 Work on elevator: mostly Daniel Kattan  Work on elevator code: mostly Stephen Joo  We did a lot of work together to ensure that physical elevator would work properly with the code

 Instrumentation lab exposed us to different instruments used by computer engineers  Oscilloscope used for measuring voltage changing with time and displays it in graphical format  Voltage displayed as sine wave (if AC current)  Used to display most EM waves  Dials on control panel are manipulated to produce unique graph shown on display monitor  Input channels allow cables of two distinct functions via two channels  Oscilloscope includes function generator which can easily change amplitude, frequency, shape of the graph, and more  Allows one to see how things should look before testing his/her circuits

DC power supply source: - gives varying amounts of power to circuits - used to supply constant voltage to circuit; this voltage can be changed to see how circuit reacts to different voltages - many of these changes are measured using oscilloscope

 In another lab, we used breadboard to build physical circuit and connect it to DC power supply source for power  We measured voltage, current, and resistance at different points around circuit  Lab allowed us to actually see what we learned in class; by actually building and measuring the circuits, we understand better what is going on

Simulation Program with Integrated Circuit Emphasis:  used for analog and digital circuit design and educational purposes  we designed circuit blueprints via this program by adding various resistors, capacitors, voltage sources, ground, and link them all together into uniform circuit  program allows you to test various circuits to ensure working design before actually building them  by building/testing circuit in PSPICE before physically building it, engineers can try out different designs and save time and money The following two images are circuit designs of various homework problems.

 Learned how to make own AM radio by soldering and connecting parts from AM radio kit  Learned how to solder correctly  Split up work of soldering parts evenly between two of us so both got practice soldering joints  Once radio was complete, we could use oscilloscope to test frequency of incoming signal.

Problem: - trouble with larger solder joints because soldering iron didn’t get hot enough to melt solder quickly Solution: - soon figured out that if we held soldering iron against joint and wire for minute or two it heats up enough to allow solder to flow evenly over joint - Would have been helpful to have different tips for soldering iron to have greater precision for our work

 Overall, the projects have helped us become better engineers and better team players  We encountered many problems faced by engineers like coordinating the simultaneous development of hardware and software.  We became better team players through our need to finish projects outside of classtime