Date Assigned: Thursday, January 26, 2012 Date Due: Thursday, February 2, 2012
Reading:
Before our labs on January 30 and 31,
please study Chapter 9, Sections 9.1 and 9.3, on frequency response and Bode plots.
Please begin studying Chapter 8 on ac power, Sections 8.1 - 8.3,
for class on Feb. 2 Tuesday, Feb. 7.
Schedule for January 30 and 31:
Lab:
Our first lab sessions will be on January 30 (2-5 PM) and 31 (1-4 PM) in Dana 305.
Please bring your your textbook, class notes, and breadboard to all lab sessions.
Lecture:
We will not have lecture on Tuesday, Jan. 31 at 8:30 AM,
and I will not be available for office hours 9:30-11:00.
The material from lecture will be covered in the lab sessions, so be prepared for the
labs to last for 3 hours.
Please check your schedule of exams and projects
in other courses and compare with the tentative exam dates on the ELEC 226
syllabus.
The proposed dates for ELEC 226 exams are
Tuesday, February 21
Thursday, February 23 and Tuesday, April 3.
Please let me know by Tuesday, Jan. 31 if these dates are bad for you.
Please solve the following problems
and submit solutions in class on Thursday, Feb. 2.
Problem 1 is an exercise with sinusoids and phasor diagrams.
Problem 2 asks you to estimate the value of a capacitor.
Problem 3: Please solve Problem 7.42 in the textbook.
Problem 4:
The following questions are very similar to the analysis in
Lab 1.
Draw a circuit with a
sinusoidal voltage source vs(t) = 1 cos( w t) (V),
a resistor (R), and a capacitor (C) in series.
Specify the output voltage vo(t)
(measured across R or C) so that the circuit will
be a high-pass filter in the sinusoidal steady-state as
the radian frequency w of the source is varied.
Find the expression for the frequency response
(or voltage transfer function) H( w ),
which is defined as the ratio of the output voltage phasor to the input voltage phasor.
Find the expression for the magnitude of the
frequency response, |H( w )|,
and the phase angle, /_ H( w ).
Make a rough plot of the amplitude gain |H( w )|
versus w.
Do this as a Bode plot of amplitude gain (in dB) versus frequency using a logarithmic scale on the frequency axis.
(You may want to determine the cutoff frequency as a function of R and C before making your Bode plot.
See the item below regarding cutoff frequency.)
Make a rough plot of the phase angle, /_ H( w )
versus w,
again using a logarithmic scale on the frequency axis.
Find an expression for the cutoff frequency wc
as a function of R and C.
Indicate the location of wc on your Bode plots
in the previous items.
The cutoff frequency is the value at which the magnitude
of the frequency response equals 1/sqrt(2) times the maximum gain
(or reduction by 3 dB on a Bode plot).
Specify values for R and C that will produce a cutoff frequency
of 1000 Hz.
(Note that wc is in radians/sec, so you need to convert
to Hz!)