Power Supplies

1
Input
Filter
Regulation
Load
Experiment 7
EE 312 Basic Electronics Instrumentation
Laboratory Wednesday, October 25, 2000
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
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
Alternator or Power Company
Load
Transformer
Filter
Regulator
Rectifier
9
Input
Filter
Regulation
Load
C
stage 1
without C
with C
10
?
v
Vmax
?
ripple
VDC
0
t
t
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.
12
Load
Transformer
Filter
Regulator
Rectifier
We design and built a 12 V dc regulated power
supply. In this experiment you use a Zener diode
that breaks down at 12 V.
13
ILoad
IDC
Iz
Iz
14
IDC
Voltage Divider
Rs
ILoad

Vinput
Rz
RLoad
Iz
15
Summary
Alternator or Power Company
Load
Transformer
Filter
Regulator
Rectifier
v
t
16
Procedures

• I- Design, construct, and test a dc power supply.
  Week 1
• II- Simulate dc power supply.
• Week 2

17
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 ?F Fixed Capacitors

18
1- Design, construct, test a dc power supply
19
v
Vmax 24.9
ripple
VDC22.4 V
Vmin19.92
0
t
t
20 ripple
20
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
21
?
RF100
Rs100
VLoad 12 V dc
CI250uF
CF100uF
Iz10.5mA
18.0 V
118.4 V
variable
Variac
22
Report is required Electronic Paper Before 1 PM
Tuesday Nov. 21