As engineers, the majority of what you have to do will involve either the words "build this to do that" or the words "how are we going to fix this so it can do that"? In most companies or organizations in which we work you will be asked to design something, build and test it, and then submit a report on it. The way the company asks you to do something is typically called a "request for action", or "task requirement" or something like that. One might look like this.

Complete the following system design project:

Required Actions

• Design, simulate and build a TTL function generator capable of outputting a square wave with adjustable frequency in the following ranges:

From this requirement you should develop in your head an idea of how you can break up this requirement into smaller tasks that you can do piece by piece (it also saves a HUGE amount of headache if you write down these ideas in your notebook as a plan). A plan of action for the above project might look this:

• Part I - Design a function generator around 555 timer chip. First just try the 1Hz to 10Hz range (if that works we can add the other ranges later). Draw the schematic in PSpice and simulate it so that you can work out any major bugs before you invest much time prototyping it.

  Part II - Add provision for the other frequency ranges in the design and build the function generator we designed on a protoboard. Test its operation from 1Hz up to 100 KHz and alter the design and schematic if you need to.

  Part III - Generate the circuit trace artwork for realization on a PCB (printed circuit board) from the PSpice schematic.

  Part IV - Using the circuit traces generated by Pspice, etch the PCB for the function generator, solder components in place and test functionality.

  Part V – Formally document your design.

Luckily you have already completed most of the steps involved in prior lab exercises.  The only thing you have left to do is the report. You must complete a formal project report for the 555 function generator project. This report is worth 10% of your final grade. The report must contain the following parts.

1. 1. Title page including name of project, name of team or division, names of team members and author, and date. In your case, since you are not working on teams, include the title, your name, date, and class.
   2. Abstract - an abstract is a concise, one paragraph description of your entire project. This may sound hard to do but it doesn't need to be. In this case a good strategy would be to include one sentence describing the needed features of the function generator you had to design and one sentence for each of the four individual labs/parts of the bigger project. Later in the report you will say all this again in greater detail - that's the idea.
   3. Design procedure - brief description of the total design process. Here you want to describe each part of the plan, each lab you did, with a few sentences in a short paragraph. Talk about what you did in Pspice - how you simulated the design - in one paragraph. In the next paragraph note anything you would want to know about building the system on the protoboard and the process of testing it. You don't need to include results as there is another section coming for that. You also don't have to be as rigid as one paragraph for each section, but remember you don't have to write a book. The goal of this part is to convey enough of the right information that someone coming to the project cold could reproduce your progress so far.  A schematic and the calculations that you used to determine component values would be a great help here.
   4. Theory of operation - Here you should describe how and why the function generator works (including the LEDs) including any equations and formulae you developed or borrowed (mention where they came from) that can be used to determine the characteristics of the system (include the equation for f_osc in this part).  You should go into enough detail that someone of your own level of expertise could pick up the report and understand the basics of how the device works. Include a block diagram of the system in question (the function generator) in this section.  The internal workings of the 555 timer, as discussed in class and outlined on the data sheet, should be included here.  A schematic diagram would make this discussion much shorter and easier to understand.
   5. Results and Conclusions - In this section you say whether the design did what it was supposed to, plain and simple. Don't try to say anything the right way, just say it. If the design did not meet the specs for each frequency range, or if it was kind'a in the gray area explain exactly what it did and how close it got.  Provide data to show how well your simulation and prototype agreed with the calculated behavior of the circuit.  Mention anything that didn't look right and briefly describe your conclusions about why it did or did not perform as expected and where you think you should go from here.
   6. Appendix - Last but not least you should include the following pertinent information in an appendix

• • • Data sheet for the 555 timer chip
  • • A BOM or "bill of materials" on which you must list what parts and materials will be used in the design (give part numbers and quantity) and their cost. Ask the lab TA's for help in finding suppliers on the web and elsewhere.

  Ethics

  Plagiarism is a very serious offense and simply will not be tolerated. Any report that has any portion copied, without a reference to the source of this copied material, is considered plagiarism. Any report exhibiting plagiarism will result in a grade of F in the class for that student.

Copyright 2003, New Mexico Tech