In general, you will have one other classmate in your team. Each of you will design and simulate an instrumentation circuit with different specifications though you will choose and use the same sensor. Thus, it is highly suggested that you communicate with your partner as early as possible to plan and coordinate your activities, select the specifications for your design, and establish a schedule. For the testing phase, you will develop a test plan and characterize and validate your teammate’s circuit.
During the project period, you are encouraged to communicate, exchange ideas, and help each other complete your project. A team area will be set up for you in Blackboard, and you are required to use this area as part of your grade will be based on effectively using this tool. Do NOT use your personal email for communication. If you use your phones or Skype, you must have meeting minutes which you post in the group area.
Each of you will submit your own Multisim file and report, which will include an evaluation of your teammate’s cooperation.
The objective of this project is to design a temperature alarm system which measures air temperature and provides an alert when the temperature exceeds its defined upper and lower limit. Specifically, a red LED should turn on when the temperature is lower than the lower limit or higher than the upper limit. When the temperature is between these two limits, a green LED should be on, indicating that the temperature is “normal.”
The options for the lower and upper limits are as shown below. Each teammate should pick a lower and upper limit, and these should be different than those of anyone else in the group.
Lower limit options: 40, 50, 60, 70 ℉
Upper limit options: 80, 90, 100, 110 ℉
The design will consist of multiple stages as shown below in Figure 1. Note that a thermistor is to be used. Also, for the “Amplification Circuit” block, use an operational-amplifier wheatstone bridge (your team will need to find this on the internet and discuss how to properly use it in your design). For the thermistor, you should use the internet to find a thermistor you want to use and use its datasheet. Teammates must use the same thermistor. A possible alarm circuit is shown in Figure 2. Don’t forget to use commonly available parts.
Figure 1: Block diagram of temperature alarm system
Once you have designed the circuit, build it and simulate in Multisim using tolerances, and then pass it to your teammate to test it.
Write a test plan and test your teammate’s design. Be sure to demonstrate that the specifications are met below the lower limit, in the normal range, and above the upper limit.
Project Troubleshooting Manual:
You and your teammate should identify one problem that could cause your design to malfunction and write a short step by step process for a technician in the field, starting with the output symptom, to troubleshoot the circuit and identify how to fix the problem. Assume that the problem is not with the power supply (supplies).
Project Deliverable: Report and the multisim design for your project
Each student will submit an individual report. The report should, as a minimum, include the following: