Observations on the Final:
General
1) Grades tremendously suffered because a lot of students do sloppy work: messy
write-up leading to forgetting terms, decimals moving around, etc. Several
students in this class broke the record in turning in the most "unreadable"
finals. Transistors were drawn with no arrows (how can one tell which end is
emitter and which end is the collector?) or worse with a circle (cannot
even say which end is the base!)
A large portion of the class would have got a better grade if they
had not made sloppy mistakes in their final!
2) Many students still do not grasp that they are trying to be an engineer not
a mathematician. Numbers are quoted with many digits and/or 23 micro A was
quoted 0.000023 A (What would you say if the lab instructions says set the
amplitude of the signal to 0.000023 V?). One student had the record.
Invariably these students made math mistakes carrying these extra digits
around.
3) About half of the students still quote numbers without any UNITS. These
numbers are meaningless.
Problem 1. (passive low-pass filter) Majority of the class got this
right. Amazingly, some stundets claimed that R_L is in parallel to R in the
circuit!
Problem 2. (Inverting Amplifier and Integrator) Almost everyone got the
inverter right. Some got the fact that the 2nd circuit is an integrator. Only
one person in the class got the correct design. This was a circuit you had
worked in the Lab! Although the problem clearly stated that "Assume OpAmps are
ideal," a good number of students looked at various limitation of OpAmp
chips!
Problem 3. (Biasing of the Darlington Pair). Majority of students got
this problem right. Good job!
Problem 4. (CMOS NOR Gate). Another Lab problem. About half of the
class got most of this problem right. A sizable minority cannot write the KVLs
correctly.
Problem 5. (BJT amplifier). Almost everyone got this right. However a
large number of math errors and/or dropped terms, invariably from students who
turn in a messy/unreadable final.
Problem 6. (OpAmp) About half of students did this problem correctly. A
large fraction wrote a node equation at V_o forgetting about the controlled
voltage source which is attached to the output of the OpAmp chip.
Problem 7. (BJT two-stage amplifier). Almost all of the student
labeled the current in the 1k resistor as I_E1. The current out of BJT
emitter is I_E! The problem hint was supposed to reinforce that.
The following two useful write-ups describe the fundamentals of Scopes and
Probes.