EXPERIMENT
#7 PRELAB
The time has come the walrus said to speak of many things
... the Walrus and the Carpenter (Alice through
the looking glass) The Walrus says just before he
eats the oysters. The time has come for us to get very
serious about the vehicle navigation circuit. The table
below lists some considerations that should be addressed
now so that the last few weeks of class are not misery
for you.
But more important than anything else, if you learn nothing
else in the class, if you forget what a chip looks like and
cringe at the mention of a transistor, you MUST, maybe that
was not big enough, you MUST learn the fine and subtle art
of debugging. We are engineers after all and this is our
signature - what sets us apart from others - the ability to
design, build, and/or fix things. The ability to debug
circuits, a program, an algorithm of any kind will serve
you well, whatever you do.
So for this lab you will be asked to debug a circuit whose
schematic is shown below. There will be many stations with
this circuit built on a protoboard. Each circuit will not
be functioning, for different reasons. You are to figure
out the reason using ONLY the multimeter. To prepare for
this challenge you are asked to think of as many possible
ways for the circuit to fail. The problem could be in the
wiring, the components, the vehicle... anything that you
can think of - creativity always makes things more fun. We
will post the best of each section.
- Fill out the truth table for the
signals L and R that are the signals which drive the
current amplifies to turn the motors on or off
- List as many different ways that
this circuit could fail if it were built on our
protoboards and tested on the track
.
EXPERIMENT #7
Rotate
through each of the stations on your side of the lab- you have 20 minutes per
station. Indicate on a drawing of the circuit where the
error occurred and indicate all of the tests that you
performed on the vehicle to come to this conclusion. Valid
tests are measuring voltage and current with the
multimeter. Taking the protoboard off of the vehicle and
making voltage and current measurements. Running the
vehicle on a track. Putting the vehicle on the stand,
running the vehicle and test the sensor function. Invalid
tests are asking other groups (either in your section or
other sections).
Half of your grade will be based on whether you identify the problem with the car. You are also responsible for writing down every change you mnake to the car, because half of your grades is based on whether you can put the car back to its original (broken) state. For every station, there will be one person that changes the car, and the other group member(s) will be responsible for documenting changes. Group members must also alternate who does what on each station. There will be a penalty if the tasks are not divided equally.
For each car you all should:
1) Write down the number of the car
2) Write down the symptoms the car is exhibiting (What is not workign correctly)
3) Write down ALL of the changes you make to the car. No matter how small.
4) Write down what you determine to be the problem for the circuit
You can use the following form