ECE 2212
PROBLEM SET 4
S. G. Burns
Due:
Wednesday, 15 February 2017
Note 1: I strongly encourage
that you start this problem set in a timely manner since there are
SPICE simulations which need to be
submitted!
Note 2: When a SPICE
simulation is required, your solution must include the circuit, model parameters
if changed from the default
values, and the relevant plots(s).
Note 3: I have been known to
collect homework design problems directly as part of the Quiz!!!
Note 4: You should be able
to solve Problems 1 through 4 with class topics through Friday, 10
February. Problem 5, requiring a bridge
rectifier, topic support will be discussed on Monday, 13 February,
along with a heat sink thermal mode Problem 6.
1.
Text 3.20 Parts (a) and (b) only. Verify your analytical answer with a SPICE
simulation. You will need to modify the
default
DBREAK
diode model for n
and IS.
2.
Text 3.19. Note the log10 (ID) versus
VD plot. This is very similar
to the parameter extraction you will address Experiment 4, 16 February. In addition to the calculations based on
Figure P3.19, generate the SPICE model and
plot of the log10(ID) versus VD characteristic for the diode and compare to
Figure P3.19.
3.
Text 3.66 Part (a) assumes
you assume the diode switches from OFF to ON when the diode voltage is zero
volts. Part (b) of problem assumes you
use the diode model that just includes a 0.65 volt battery when the diode
switches from OFF to ON. The best 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.
4.
Based on an old quiz problem.
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).
(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!).
(h)
A
voltage regulator is not required
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.
