June 26, 2011
June 26, 2011
June 29, 2011
Division Experimentation & Lab-Oriented Studies
22.1420.1 - 22.1420.18
Temperature Alarm Laboratory Design Project for a Circuit Analysis Course in a General Engineering CurriculumWe have developed and delivered an integrated multi-week operational amplifier-basedlaboratory design project as a means to enrich our students with an electrical engineering designexperience within our general engineering program. The design project is presented in a circuitanalysis course, which is only one of two electrical engineering-based core courses in ourprogram, the other being a combined instrumentation and control systems course. Our goals areto support the outcomes of the program with sufficient coverage of electrical engineering topicswithin these two courses and to ensure the success of our students as well-rounded engineers bycovering key topical design areas. This design project is one of the critical components inachieving these goals.The students are assigned to design a temperature alarm system that measures air temperatureand provides an alert when the temperature exceeds certain upper and lower limits. The multi-week format is used to integrate successive stages of the instrumentation system into digestibledesign tasks. This helps the students hone their design skills by focusing on one aspect of theentire system design and making appropriate connections on how each stage impacts thebehavior of their entire system. Each stage of the system focuses on different applications ofoperational amplifiers. The first design stage is the development of an operational amplifier-based Wheatstone bridge circuit consisting of a resistive network that contains a thermistor as thesensor. The students also model their sensor system by writing appropriate Matlab scripts thatsimulate the behavior of the circuit as a function of temperature. The second design stage is thelinearization of the thermistor-based Wheatstone bridge circuit. Since the resistance of athermistor is an exponential function of temperature the students are required to design theresistive network of their amplified bridge circuit to meet specific linearization requirements.The students use their Matlab models to test their circuit designs and characterize the responseswith respect to temperature. The third design stage is the development of a circuit that comparesthe output voltage of the amplification thermistor circuit with voltages representing specifictemperature upper and lower limits. This stage reiterates the concept of representing physicalquantities with electrical signals. The fourth stage is the design of an alarm circuit that alerts theoperator with LEDs when the measured temperature is out of range. The design loop is thenclosed by integrating, testing, and characterizing the entire alarm system followed by a formalreport describing the work of the project. Our assessment of how this laboratory experienceimpacts the students’ ability to meet the course objectives and the program outcomes is based on:1) How well the students communicate specific design aspects in the formal report; 2) How wellthey communicate their linearization methods using Matlab; 3) A survey on how well thestudents believe they are meeting the course objectives associated with the laboratory project;and, 4) the successful completion of embedded questions in the final exam associated with thedesign project.
Limberis, L., & Yao, J. (2011, June), Temperature Alarm Laboratory Design Project for a Circuit Analysis Course in a General Engineering Curriculum Paper presented at 2011 ASEE Annual Conference & Exposition, Vancouver, BC. 10.18260/1-2--18685
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