Power Supplies

1
Input
Filter
Regulation
Load
Experiment 8
EE 312 352 Introductory Electronics
Laboratory November 1, 1999
2
Objective

• Design, construct, and test a dc power supply.
  The power supply includes a transformer, diodes,
  and a filter. All were investigated in previous
  experiments. This the major design project in the
  course.

3
DC-VOLTAGE POWER SUPPLY OPERATION
Alternator or Power Company
Load
Transformer
Filter
Regulator
Rectifier
v
t
4
Load
Transformer
Filter
Regulator
Rectifier
5
Load
Transformer
Filter
Regulator
Rectifier
v
118 Vrms
167
16.7 ms or 60Hz
t
6
Load
Transformer
Filter
Regulator
Rectifier
60Hz
RLoad
120Hz
v
t
RLoad
full-wave rectifier
7
Load
Transformer
Filter
Regulator
Rectifier
v
60 Hz
0.6V
24.9
12.45 Vrms
t
t
half-wave rectifier
8
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9
Input
Filter
Regulation
Load
C
stage 1
without C
with C
10
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11
stage 2
One or more filter sections are usually used to
reduce the amplitude of the ripple. The filter
used in this experiment is a single-section
low-pass RC filter.

• V across R lt 25 of Vinput

usually tolerable
12
Ripple Reduction Factor
Vout
Vin
13
Load
Transformer
Filter
Regulator
Rectifier
You are asked to design and built a 12 V dc
regulated power supply. In this experiment you
use a Zener diode that breaks down at 12 V.
14
ILoad
IDC
Iz
Iz
15
IDC
Voltage Divider
Rs
ILoad

Vinput
Rz
RLoad
Iz
16
Summary
Alternator or Power Company
Load
Transformer
Filter
Regulator
Rectifier
v
t
17
Procedures

• I- Design, construct, and test a dc power supply.
• II- Simulate dc power supply. I

18
Components

• 18 Volts Transformer
• Variac
• Bridge rectifier (use 1 diode)
• Zener diode (Vbd12Vdc, 1N4742)
• 12 Watt, 1000 Ohm, variable resistor
• 2 Resistor Substitution Boxes
• 50, 100, and 200 UF Fixed Capacitors

19
1- Design, construct, test a dc power supply
Suggestion Zener diode current 21 mA
(At this current, the
Zener resistance is 9 ohms)
20
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21
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22
v
Vmax
ripple
VDC
0
t
t
23
20 ripple
v
Vmax 24.9
lt 24.9 x 0.24.98 V
ripple
VDC22.4 V
Vmin19.92
0
t
t
24
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25

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2- Simulation of Part I
Simulate the dc power supply! Show output wave
form at points 1, 2, and 3. Comnpare these
waveforms with your experiment.
1
2
3
28
18.0 V
118.4 V
variable
Variac
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Report is required for EE 312 352