Download Avaliação da fonte de alimentação

Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
Students: _________________________________________________________________________
________________________________________________________________________
Complete the task and forward it by e-mail to [email protected]
With the power supply you have built, proceed to the following experiments:
1) Quality rating of the transformer:
An ideal transformer keeps its output voltage even with a load that draws its nominal output current. In
addition, its nominal output voltage level should remain, when the circuit is open. In our experiment, to
assess the transformer quality you need two 15 watts resistors, one of 22 ohms and another of 15 ohms.
Figure 1 – Transform terminals are available through J3 connector.
Output transformer voltage measured with a voltmeter.
No-load
R1=37 ohms
Transformer wires
VRMS
VDC
VRMS
VDC
V1: T1 - CT
V2: T2 - CT
V3: T1 - T2
Δ% (VRMS)
1
Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
2) Waveform in the transformer output.
To visualize the voltage waveform in the transform terminals it is necessary to use attenuated oscilloscope
probes. In some probes, it is also necessary to change the attenuation on the probe to 10X. In the
oscilloscope set the probes attenuation to x10.
Capture the oscilloscope screen and insert in the table below. Before capturing, set the screen
measurements, so it indicates the voltage peak-peak, RMS and DC.
Insira aqui
V1
Ajuste a hora e o dia no menu do osciloscópio
antes de capturar a imagem com pen drive.
Insira aqui
V1
Transform waveform with no-load
Transform waveform with a load.
3. Spectrum of the transform waveform:
Using the FFT function of the scope, watch the frequency spectrum of the waveform voltage of the
transform with the load indicated in Figure 1. Capture the oscilloscope screen and insert in the table
below. Indicate the 60Hz component.
Insert here the spectrum
Ajuste a hora e o dia no menu do osciloscópio antes de capturar a imagem com pen drive.
2
Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
4) Draw the pin assignment of the 7812 regulator
5) Copy from the Fairchild LM7812 datasheet the schematic diagram for a fixed 12V regulator. In the
diagram specify the capacitor (capacitance, type (if electrolytic, ceramic, tantalum) and the voltage
isolation).
6. Complete the table using the Fairchild LM7812 datasheet
Values indicated in the datasheet
Maximum input voltage:
Output voltage (Min, Typ, Max )
Short circuit current:
Dropout voltage:
Output current:
Component package:
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Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
7) Voltage in the input and output of the 12V regulator LM7812.
With the oscilloscope verify the signal waveform in the input and output pins of the LM7812. Before
capturing the screen, set the measured values to voltage peak-peak, RMS and DC.
Formas de onda sem carga na saída do regulador LM7812
Inserir aqui
Ajuste a hora e o dia no menu do osciloscópio
antes de capturar a imagem com pen drive.
Inserir aqui
Input voltage
Output voltage
Formas de onda no LM7812 com carga de 15 ohms na saída LM7812.
Inserir aqui
Ajuste a hora e o dia no menu do osciloscópio
antes de capturar a imagem com pen drive.
Input voltage
Inserir aqui
Output voltage
4
Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
8) Determine the waveform ripple in the input and output of the LM7812 with a load of 15 ohms.
Input
output
input
No-Load
output
With 15 ohms Load
9) Short circuit current:
Using a 15 watts resistor of 4.7 ohms as a load connected to the 12V output regulator, measure the
voltage and current through it.
Voltage:________________________________
Current (Voltage/4.7=):__________________________________
9) Copy from the datasheet the schematic diagram for the LM317 e LM337 regulators. In the diagram
specify the capacitor (capacitance, type (if electrolytic, ceramic, tantalum) and the voltage isolation).
a) Draw the pin assignment
b) Copy from the Fairchild LM317 e LM337 datasheets the schematic diagram. In the diagram specify
the capacitor (capacitance, type (if electrolytic, ceramic, tantalum) and the voltage isolation).
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Federal University of Technology - Paraná
Electronics Department
Course: EL65E -Eletrônica Básica
1st Semester 2016
Additional homework
10) Draw a sketch of the rectifier circuit (including transformer and capacitors) used in the power
supply, and explain how does it works. How is it possible to obtain the positive and negative voltages?
Sketch
How does it works ?
11. Draw a sketch of a rectifier circuit, capacitive filter and select a linear regulator for a -9V (minus nine
voltage) and 1.5A.
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