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EE438
Homework #5
Zener Diode Regulated Power Supply
In the circuit below, a Zener diode regulator is used to stabilize the load voltage of a peak
rectifier. Use the following information to model the components in the circuit.
Transformer
Primary 115 VAC 60Hz
Secondary
25.2 VAC
CT
12.6
VAC
12.6
VAC
115 VAC
C
R
1N5239B
Zener
1N4001GP
1N4001GP
I
L
V
L
+
_
I
Z
V
SDC
1N4001GP
V
D0
= 0.7 V
r
d
= 0
Ω
1Ν5239Β
V
Z
= 9.1 V
I
ZT
= 20 mA
r
Z
= 5
Ω
1.
a) For a Line Voltage of 115 VAC determine the value of R that will have I
Zmin
= 5 mA
for load current (I
L
) variations of from 0 to 50 mA.
b) For a Line Voltage of 115 VAC use the value of R determined in a) to compute the
maximum and minimum values of the Load Voltage, V
L
, for variations of the load
current, I
L
, from 0 to 50 mA
c) Use the value of R determined in a) to compute the maximum and minimum values of
the Load Voltage, V
L
, for variations in the line voltage from 110 VAC to 120 VAC
for a load current I
L
= 50 mA.
d) Assuming that the Line Voltage is 115VAC and using the value of R determined in a),
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 Spring '08
 Cardwell
 Volt

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