EE 2212
PROBLEM SET 3
S. G. Burns
Due:
Wednesday, 13 October
1.
Text 3.66. Piecewise linear models should be used. Part (a) assumes you assume the diode
switches from OFF to ON when the diode voltage is zero volts. Part (b) assumes
you use the diode model that just includes a 0.65 volt battery when the diode
switches from OFF to ON. The best
systematic
approach is to draw out each circuit and then look for any potential
contradictions with the diode model and circuit when you assume a diode is
either ON or OFF. Sketching a
piece-wise linear
I-V
characteristic is one approach to piece-wise linear problems. Prepare a table
to
summarize your results.
2.
Assume
a diode p-region is doped NA=
5 x 1015 cm-3 and the diode n-region is doped ND=
8 x 1016 cm-3. Compute VJ (Diode turn-on
voltage). Repeat for NA= 3 x
1018 cm-3 and the
diode n-region is doped ND= 1 x 1017 cm-3. Assume
ni= 1.0 x 1010 cm-3.
3. Based on an old quiz problem related to half-wave
rectifier design. You may need your design
if we have cold weather this
winter. You are to design a battery
charger for safe operation in a damp garage environment to use for charging your 12 VDC car battery.
Design specifications include:
(a)
Input
is a 110rms VAC. (VP=110x
) at 60 Hz from a three wire service that meets
the National Electrical Code.
(b)
Output
is a nominal 12 volts VDC at the cathode of the diode.
(c)
Specify
a resistor, R, to limit the maximum
battery charging current to 10 amperes into the 12 volt car battery assuming
the battery is completely dead (0 volts) when you first connect the
charger. A not uncommon occurrence over
the last two weeks of sub-zero temperatures.
(d)
There
is no ripple voltage design specification.
Explain why this is unnecessary in this application.
(e)
The
battery charger case is metal.
(f)
Assume
a diode with VF = 0.7 V
(g)
The fuse in the primary circuit is to protect the
power supply from a short-circuit at the battery terminals either from total
battery failure or accidentally short 
circuiting the charging cable to ground. (For
example, dropping a wrench across the battery terminals-oops!).
Your Design must include:
Well-labeled circuit diagram including the identification
of the incoming “hot”, “neutral”, and “ground wires (U.S.
standards) including the National Electric Code color coding of these wires and
also show the correct color-coded wiring for a standard grounded duplex
receptacle and plug.
i.
Key
design equations and supporting calculations
ii.
Component
specifications including:
· Transformer-turns ratio
· Diode-current and power ratings
· Your assessment and short discussion as to whether
the laboratory 1N4001 diodes could be used
· Value for R1 serving as a current limiting
resistor
· Current rating of a fuse in the primary circuit to
protect the power supply against a short circuit condition at the battery
terminal.
4. Similar to an old quiz
problem. Design a +40 volt dc power
supply for your sound system. Your sound
system requires a 400 watt
capability. The power supply is energized from a
three-wire 110 Vrms 60 Hz power line that meets
the National Electric Code
(NEC). The system block diagram and design
specifications are given below.
· Input
is a 110 Vrms 60 Hz.
· Output
voltage is 40 volts, unregulated.
· Maximum
allowable ripple is 2%
· Use
a full-wave bridge rectifier.
· Use
a transformer
· Assume
diodes with VF = 0.7 volts
Your design should include:
Ø Well-labeled circuit
diagram of what goes in the “Your Design” box. There should be
enough detail such that someone could build
an operational prototype. Polarities of key
components are important
Ø Key design equations and
supporting calculations. Show your work!
Ø Component specifications
including:
(a) Transformer-turns
ratio
(b) Effective
value of the audio system load resistor (speaker
impedance) and load current for a 400 watt, 40 volt system.
(c)
Capacitor value to satisfy
the 2% ripple voltage specification.
(d) Bridge
rectifier diode-current and power ratings.
(e)
Correctly located primary circuit fuse and its
rating.
(f) Correct
(NEC specified safe wiring) to the three wire power line
receptacle.
5. Tuned Circuit Design Using a VARICAP
(a) Refer to the
capacitance curves for the Motorola 1N4002. 1N400XCap.JPG The input tuning circuit
of a standard analog FM radio is given below. Specify,
that is design for, a voltage, capacitance, and
inductance required to tune the circuit to
the center frequency of KUMD-FM which operates at
103.3 MHz. (By the way-Did you know that KUMD is probably
going to be sold to WDSE-Local PBS Station) Sketching and
labeling a representative resonance curve is required to support your
calculations. There is no single correct design answer set of values
since it depends upon the voltage you initially select to tune your diode.
(b) Repeat if
you use the Motorola MMBV109LT1 MV209. Refer to the EE 2212
WEB pages Hyperdiode1.JPG and HyperDiode2.JPG
Since we are talking about
converting AC to DC (you have seen this one before):
I will provide free lessons on how to use a slide
rule via ZOOM . It really helps you to
understand log10 calculations.
BYOSR (Bring Your Own Slide Rule).
All of you are now far enough along in your
engineering studies to appreciate a full-blown version of Murphy’s Laws
I have been
emphasizing units and unit conversion
throughout the semester. Here are some
additional conversion factors you should be aware of. They are best reviewed over a beverage of
your choice. Sorry, it doesn’t get any
better than this.
SPECIAL UNITS AND
CONVERSION FACTORS
Ratio of an igloo's
circumference to its diameter: Eskimo Pie
2000 pounds of Chinese
soup: Won Ton
1 millionth of a
mouthwash: 1 microScope
Time it takes to sail 220
yards at 1 nautical mile per hour: Knot-furlong
365.25 days of drinking a
low-calorie fermented malt beverage of your choice: 1 lite-year
16.5 feet in the Twilight
Zone: 1 Rod Serling
Half of a large intestine:
1 semicolon
1,000,000 aches: 1
Megahurts
Basic unit of laryngitis:
1 hoarsepower
Shortest distance between
two jokes: A straight line
454 graham crackers: 1
pound cake
1 millionth of a phone: 1
microphone
1 million phones: 1
megaphone
1 million bicycles: 2
megacycles
2000 mockingbirds: two
kilomockingbirds (This is a bit subtle from an English literature class)
10 cards: 1 decacards
1 kilogram of falling
figs: 1 Fig Newton
1000 grams of wet socks: 1
literhosen
1 millionth of a fish: 1
microfiche (a film-based somewhat
archaic approach to store written documents)
1 trillion pins: 1
terrapin
10 rations: 1 decoration
100 rations: 1 C-ration
2 monograms: 1 diagram
8 nickels: 2 paradigms
2.4 statute miles of
intravenous surgical tubing at Yale University Hospital: 1 IV League
I suppose I should
apologize for the quality of these
jokes, but I won’t!