Experiment # 7

EE 312 Basic Electronics Instrumentation Laboratory

Wednesday, October 25, 2000

Input Filter Regulation Load

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.

Transformer Filter RegulatorAlternator

orPower Company

Rectifier Load

t

v

Input: 120 VAC RMS, 60 Hz

Steps the input voltage up and down as needed

Convert the ac to a pulsing dc

Low-pass type for removing voltage variation

Keeps voltage constant regardless of load change

DC-VOLTAGE POWER SUPPLY OPERATION

Transformer Filter RegulatorRectifier LoadPower Company

t

v167 118 Vrms

16.7 ms or 60Hz

Transformer Filter RegulatorRectifier LoadAlternatoror

Power Company

t

v167 118 Vrms

16.7 ms or 60Hz

t

v25.5 18 Vrms

16.7 ms or 60Hz

Transformer Filter RegulatorRectifier LoadAlternatoror

Power Company

t

v

RLoad

RLoad

t

v

half-wave rectifier

full-wave rectifier

60Hz

120Hz

Transformer Filter RegulatorRectifier LoadAlternatoror

Power Company

t

v25.5 18 Vrms

16.7 ms or 60Hz

~ 0.6V

t

v

half-wave rectifier

24.960 Hz

12.45 Vrms

t

Transformer Filter RegulatorRectifier LoadAlternatoror

Power Company

Input Filter Regulation Load

stage 1

stage 2

t

v

tt

v

t

et

RC

Vmaxripple

Input Filter Regulation Load

stage 1

without C with C

C

t

vVmaxripple

t

VDC

0

t

V??

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.

Input Filter Regulation Load

C

R

Vinput

Transformer Filter RegulatorRectifier LoadAlternatoror

Power Company

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.

ID

VD

ForwardCharacteristics

ReverseCharacteristics

12Voltsbreakdownvoltage

~~ IMax

Iz

ILoadIDC

Iz

ID

VD

~~ IMax

RLoad

Rs

Rz

IDC

ILoad

Iz

RLoad

Rs

Rz

IDC ILoad

Iz

Voltage Divider

=

V

V

R

R R

z DC

input

z

s z

,

Vinput

V

V

r

R r

z ripple

input ripple

z

s z

,

,

1

Rz1

rz

Transformer Filter RegulatorAlternator

orPower Company

Rectifier Load

t

v

Summary

Procedures:

I- Design, construct, and test a dc power supply. Week 1

II- Simulate dc power supply.

Week 2

Components:• 18 Volts Transformer

• Variac

• Bridge rectifier (use 1 diode)

• Zener diode (Vbd=12Vdc, 1N4742)

• 12 Watt, 1000 Ohm, variable resistor

• 2 Resistor Substitution Boxes

• 50, 100, and 200 F Fixed Capacitors

1- Design, construct, test a dc power supply

VLoad =12 V dc

ILoad = ?

Peak to peak ripple voltage from the input stage = ?

Peak to peak ripple voltage at the load = ?

R? R?

C? R?C?

t

vVmax = 24.9ripple

t

VDC=22.4 V

0

t

V

20% ripple

Vmin=19.92

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

VLoad =12 V dc

RF=100 Rs=100

CF=100uFCI=250uF

511LR

Iz=10.5mA?Variac Transformer

18.0 V118.4 V variable

Report is requiredElectronic & Paper

Before 1 PM Tuesday Nov. 21