LABORATORY REPORT

 

GUIDELINES

 

 

 

  INTRODUCTION:

 

     The prime objective of a laboratory report should be to have information, flowing in a natural progression, which will make the lab understandable to anyone running the same test(s) at a later date. It should be complete enough to allow that the person to duplicate the setup used and obtain the results you obtained, within reason. It should leave no questions as to how the test was performed and what was obtained. In other words, it should be a STAND-ALONE DOCUMENT.

 

  The following paragraphs will describe such a document. It will provide as outline of steps and description of each step with examples. Close attention to this procedure will result in a lab report that will fulfill all of the requirements of a complete stand-alone document.

 

 

LABORATORY FORMAT:

 

             A complete lab report which satisfies that intent of such a report, should contain the following sections:

 

    *     OBJECTIVE

   

    *     EQUIPMENT LIST

 

*     BLOCK DIAGRAM

 

    *    PROCEDURE

 

    *    DATA

 

    *    CONCLUSION

 

    *    QUESTIONS

 

 

                Each of the sections will now be presented with the explanation of each and examples.

 

 

 

OBJECTIVE:

 

         This is the section, which sets the tone foe the lab. It is the section, which describes to the reader what is to be accomplished by the tests. With the words used in this opening paragraph you must get the attention of the reader so that they will have an interest in the entire report. Many times a weak objective statement will destroy what is an excellent lab. So, put some time and thought into what you will say in this opening statement. It usually does not need to be more than one paragraph long. Many times a longer objective statement will detract from the lab. You will not need to say a lot in this statement, you need to say the right things.

 

                                                    

                                                         BAD EXAMPLE

 

                                 “In this lab we will test Operational Amplifiers.”     

 

 ( This statement is far too general. It does not tell the reader anything specific about the tests. A reader could not tell if they could use this lab or not. )

 

                                        

                                                        GOOD EXAMPLE

 

   “This lab is designed to provide a method for testing operational amplifiers for high frequency applications. Such properties as gain, feedback requirements, and current requirements will be tested.”

 

( This statement is much more specific for the reader. If the reader does not need high frequency data, they can ignore this lab. If they DO need high frequency data, this is the lab for them and they know it from the first paragraph of the lab. ) 

 

 

EQUIPMENT LIST:

 

          This is probably the most overlooked section when individuals put a lab report together. They sort of take for granted the equipment they use. The model or the serial number seems to be of no importance to them.

 

           Actually the test setups contained in the lab could never be duplicated if the individual wanting to run the test again did not know such things as model and serial number of the equipment. This is because you must have the same equipment, if possible, in order to accurately duplicate a setup and results. 

 

 

          In order to have a good equipment list for your lab report, you must list three things for each piece of equipment:

 

            *     NAME OF EQUIPMENT            

 

            *     MODEL NUMBER OF EQUIPMENT

 

*     SERIAL NUMBER OF EQUIPMENT  (If available)

 

            These three items will give you an accurate description of the equipment that was used to obtain the data in the report.  

 

           

             When we speak of equipment we sometimes think only of items such as generator or oscilloscopes or meters. There are, however, some smaller items, which are often neglected but are of vital importance. These are items such as cables, adapters, or tests leads. These items will make it impossible to run the tests if they are not gathered by the individual who wants to duplicate the tests. If you think of the equipment list for your lab as a grocery list you must compile in order to survive for a specified number of days, it may be easier to put it together.

 

             THIS MUST BE A COMPLETE LIST OF EVERY ITEM YOU WILL NEED TO CONDUCT THE TESTS THAT ARE REQIURED FOR THIS LAB.

 

 

EXAMPLE

 

               

 The following equipment is needed to conduct the tests of this lab: 

 

1.      Generator, HP 1605, Ser # 33468  

 

2.      Attenuator, HP 87556, Ser # 5112

 

3.      Detector, Alford 334, Ser # 309

 

4.      Thermistor Mount, HP 478B, Ser # 556

 

5.      Power Meter, HP 431, Ser # 555678

 

6.      Cables, RG 58 / U, 3 ft. in length

 

7.      Adaptors, SMA-to-Type N (Male adapters) 4 each

 

 

   It can be seen from this list that an individual could gather the items listed and could be assured that they would not get half way through the lab and find they needed more equipment. This should be the goal of your equipment list. It should be a complete list that needs no addition.

 

 

BLOCK DIAGRAM:

 

    The block diagram is exactly what the name implies. It is a diagram of blocks, which show the reader to connect the test setup. Not only must the names of equipment be included on this diagram, but all input and output connections used should also be labeled on the equipment. This aids greatly when an individual has to set up the equipment for duplication of the test(s).

 

       It is very good practice, and also looks much better, to do all the block drawings with a straight edge. Free hand drawings so not look good in a finished report. It indicated that the writer of the report does not care enough about the report to do a neat job. To understand this statement, consider the example shown below and the one that follows. The first one is rough and difficult to read. The second one leaves no doubt as to what has to be connected where. Thus, remember to always clean up the diagrams----- USE A STRAIGHT EDGE.

 

 

                                                         BAD EXAMPLE

        

                                                                                                        

 

                  Sweet                                 

 

 


Scope

 
                                   

 

 

 

 

 

 

 

 

 

 


                                                                                                    Det

 

 

 

 

 

 

                                                          GOOD EXAMPLE

 

 

 

 

                      Sweet Out                                                       

                                                                                                                                       Hor.

                       

 

Generator                                                                                                Scope

 

 


                                RF Out                                                                                           Vert.

                                                                                                                 

                                                                            Device                          

                                                                        under test

                                                                                                         Detector           

 

 

 


                                           Attenuator

 

 

 

An alternate means of making a block diagram and including the list of equipment along with it is shown below. This method has been used frequently to combine the two sections. Be sure that you co-ordinate the list of equipment with the numbers you put on the diagram. It could be disastrous if the numbers got mixed up.

 

 

 

 

 

ALTERNATE EXAMPLE

 

 

 

1.  Generator, HP 608. Ser # 456

 

2. Attenuator, HP 8776, Ser #3323

 

3.  Device under test

 

4.  Detector, HP 423, Ser # 9105

 

5.  Oscilloscope, Tektronix, 545, Ser # 455678

 

 

 


         Sweet Out

                  

5
 

 

 


            RF Out

 

 

 

 

 


 

 

 

 

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            PROCEDURE:

 

 

   This is the heart and soul of the lab report. It is where the entire lab is explained (in detail). The best way to accomplish this is to have one person conduct the lab while another writes down each step as it occurs.

 

 

  When the statement is made that you write down EASH STEP, this is exactly what it means. You must make the assumption that next person to perform this test knows very little, if anything, about how to perform it. If you assume this you will automatically write a detailed procedure. (This is one place where you are encouraged to assume

something.)      

 

 

           To illustrate the type of procedure needed, the following examples are presented. One is undesirable, while the other is a good example of what we mean by DETAILED.                                                                                                                                                    

 

 

 

 

BAD EXAMPLE

 

 

1.      Connect the test setup.

 

2.      Set the frequency to 5 KHz.

 

3.      Read the output on the scope.

 

4.      Change the frequency to 6, 7, 8, 10, and 15 KHz and repeat steps 2 and 3.

 

 

 

 

 

GOOD EXAMPLE

 

 

1.      Connect the setup as shown in the BLOCK DIAGRAM SECTION with the device under test removed. (The diagram may also be referred to by figure number.)

 

2.      With the device out of the circuit and attenuator connected to the detector, set a reference level on the oscilloscope.

 

3.      Place the device to be tested back into the setup.

 

4.      With the frequency set at 5 KHz, apply DC voltage to the circuit and note the new output level on the scope. Record this level.

 

5.      Set the generator to 6 KHz, repeat step2 for a new reference level.

 

6.      Repeat steps 3 and 4 to obtain the measured level of the output.

 

7.      Set the generator to 7, 8, 10, and 15 KHz and repeat steps 2, 3, and 4.

 

8.      Plot the final results as a gair VS. frequency plot.

                                                                                                                                                                                                                                                                                               

 

               It can be seen how much more concise the second procedure is. In this, the steps are distinctive and are not general as the ones in the first example. There should not be any questions about a procedure that is properly written. It should answer any question as an individual proceeds through it.

 

DATA:

 

 

          There is one term that consistently comes up when looking at data that is collected both in education and industry. That term is LABEL. In order to have the date you have so carefully taken understood you must LABEL, LABEL, LABEL. Label the axis you are using for a vertical presentation. Label the curves that result from your data taking, particularly if there is more than one curve on a set of axis. You could have taken an excellent set of data, but if you cannot properly display it it is worthless.

 

 

          Consider the plot below. It appears to be made of nice straight lines for each axis and has a very nice set of curves displayed. It is, however, good for nothing at all. First, you do not know what units are used for frequency or amplitude and second, you do not know what each of the curves represents. So, as we have said, it is good for nothing at all.

BAD EXAMPLE

 

 

A
F
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


GOOD EXAMPLE

 

 

 

       Now look at this example and compare it to the one above. This one has the horizontal axis as frequently in MHz; the vertical axis as amplitude in volts; the curves are labeled for a variety of resistances; and the entire sheet of data ha a title which explains why it is in this report. This is a much more useful piece of paper than that shown above.

 

                                                                                                R=10 K

           

AMPLITUDE -- Volts
 


                                                                                                R=1 K

 

 

                                                                                                R=100 Ohms

 

                                                                                               

                                                                                                Amplitude Vs. Frequency        

                                                                                                For QA 105 Amplifier

                                                                                                 

FREQUENCY -- MHz               

 

When tabular data is used, it should also be very well labeled. All columns of the data should be labeled and should be straight so that anyone who wished to obtain a particular reading will be able to do so with relative ease.

 

 

CONCLUSION:

 

 

            This is one of the most important parts of the lab report. It either confirms that everything has gone well or tells why it didn’t. It is a summation of everything that has been done in the laboratory. Two examples will show how the conclusion should not and should be written.

 

 

BAD EXAMPLE

 

          “This experiment introduced me to the audio amplifier. It worked very well.”

 

 

           This conclusion tells that the person who conducted the tests did not care much about the tests. In fact I can not be sure the person conducted any tests at all.

 

 

GOOD EXAMPLE

 

         “The previous experiment illustrated the operation of a variety of audio amplifiers. Gain was verified for all devices tested. The frequency response, however, could not be completely tested because of a problem with the audio generator. It only produced an output up to 5 KHz. This is why the data enclosed only goes to that point. Other than this malfunction of the equipment, the experiment went very well.

 

 

     This example shows that the individual not only did the lab, but also had enough knowledge to detect that something was not right. This makes a very complete conclusion to a lab.

 

 

 

QUESTIONS:

 

    Some labs have questions attached to them, some do not. If there are questions to be answered, they are to be put after the conclusion of the lab.

 

 

    The questions to be answered should be written in the lab report and then complete answer should be placed under them. It is to your credit if you can include drawings or formulas that will substantiate your answers.

 

 

GENERAL RULES

 

 

*   Be concise with the report

 

*   NEVER USE PENCIL FOR A LAB REPORT—NOT EVEN FOR DRAWINGS

 

*   If a mistake is made, place one line through the mistake and initial the mistake

 

*   Sign and date the last page of the lab report    

 

*   Title page

 

 

 

                                                                                                    

                                                                                                       

 

                                               

 

Copyright ©  Thomas S. Laverghetta, Professor, ECET Dept – IPFW®.