EE 2212
PROBLEM SET 4
S. G. Burns
Due:
Wednesday, 24 February
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 adiode 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.
Text 3.19.
Note the log10 (ID) versus VD
plot. In addition to the calculations based on Figure P3.19, generate the SPICE model and plot of thelog10(ID)
versus VD characteristic for
the diode and compare to Figure P3.19. Refer to Slide 2 of the 10 February PPT “Diode
Equation and Half-Wave Rectifier..
3.
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.
Refer to Slide 6 of the 8 and 10 February PPT “Energy Levels and Start
Diodes”.
4. Based on an old quiz problem related to half-wave
rectifier design. You may need your
design if the cold weather continues. 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.
5. You
are to design a +9 volt and -9 volt
dual voltage bench power supply that you can use to power a μA 741
operational amplifier. This would
replace the two 9-volt battery packs you are using in our lab. 
