Download Printed Circuit Board

Power Supply Project
Prepared by:
Anthony Lockhart
(100529268)
Course Code: CAD 1133
Course Name: CAD for Electronics I
Date: April 16th, 2014.
Submitted to: Professor Denis Grenier
1
Abstract
The purpose of the project was to design a 0 V-15 V supply (positive and negative).
Also, a 5V fixed supply. The circuit was created with Multisim in order to simulate and
understand how to circuit worked. Next the circuit was created on the program Eagle
in order to create the PCB (printed circuit board). The board was created using Eagle.
When using Multisim, the simulation of various sections of the circuit was broken into
chunks to gain a better understanding of how it operates. The different sections were
the 5V fixed supply and the positive 0V-15V.
When using Eagle, the schematic of the circuit was to be completely drawn first, with
the proper components in the right location. They needed to be connected properly
in order for the circuit to work. Once that was completed, the actual board of the
circuit was created and routed. The components all had to be placed on the board in
such a way that it was possible to route it correctly.
Once the board was created using Eagle, it was created into a transparency in order
to project the routes onto the PCB in the lab. Once the PCB was created through
various steps, it was then drilled to make holes to insert the components and solder
them onto the board.
Once the whole PCB was populated and soldered, it was then screwed onto the inside
of the box we were given. The binding posts were installed and the appropriate wires
were soldered onto the posts. A fuse was put into the circuitry for safety. A display
was given to each student which would display the voltage the box was outputting at
the time.
2
Acknowledgements
I would like to thank Denis Grenier for the help with the PCB. For explaining in the
simplest way possible on how to route in Eagle. Also for helping out with issues with
routing. Thank you also for showing us the issues with our routing and finding the
ways around it to fix it. Secondly, I would like to thank Dave MacKay for his help
when creating the PCB in the lab. He was a great help with instructing us what to do,
and also explaining how the different machines functioned.
3
Contents
Title Page............................................................................................................................................1
Abstract...............................................................................................................................................2
Acknowledgments...........................................................................................................................3
Contents..........................................................................................................................................4/5
List of Figures...................................................................................................................................6
Section A.............................................................................................................................................7
Introduction and Purpose
The Power Supply Project
Aims of the Project
Section B.........................................................................................................................................8/9
Schematic and Circuit Operation
Operation of the Power Supply...............................................................................................10
Power Rectification
AC-DC Rectification...............................................................................................................11/12
Fixed 5V Power Supply........................................................................................................13/14
0-15V Variable Power Supply............................................................................15/16/17/18
0-15V Variable Power Supply (Negative)...........................................................................19
Op Amp...............................................................................................................................................20
Section C.............................................................................................................................................21
Printed Circuit Board
Eagle Schematic
Printed Circuit Board Layout............................................................................................22/23
Printed Circuit Board Production...................................................................................24/25
SectionD…………………………………………………………………………………………………….26
Box Drawing
Box Production………………………………………………………………………………………….27
Box Assembly…………………………………………………………………………………………….28
4
Final Assembly and Testing………………………………………………..…………………29/30
Final Assembly
Testing
Summary and Conclusion………………………………………………………….....……….31/32
Schematic Drawing
Printed Circuit Board Drawing
Printed circuit Board Production
Box Drawing
Box Production
Assembly and Testing
5
List of Figures
Figure 1 – Incomplete Schematic......................................................................................8
Figure 2 – Complete Schematic........................................................................................9
Figure 3 – Power Rectification........................................................................................10
Figure 4 – AC and DC Rectification on Oscilloscope....................................................11
Figure 5 – AC and DC Reading Circuit..........................................................................12
Figure 6 – 5V Supply Circuit..........................................................................................13
Figure 7 –Multimeter Reading
Figure 8 – Smooth 5V DC...............................................................................................14
Figure 9 – 0V - 15 V Variable Supply at 100%..............................................................15
Figure 10 – Multimeter Reading With Pot at 100%........................................................16
Figure 11 – 0 V – 15V Variable Supply at 0%................................................................17
Figure 12 – Multimeter reading with Pot at 0%..............................................................18
Figure 13 – 0 – 15V Variable Supply (Negative)............................................................19
Figure 14 – Multimeter Reading at the Output of the 337...............................................19
Figure 15 – Eagle Schematic………...............................................................................21
Figure 16 – Complete Eagle Board.................................................................................22
Figure 17 – Eagle with Copper Pour...............................................................................23
Figure 18 – All Punching and Drilling Templates..........................................................25
6
Section A
Introduction and Purpose
The Power Supply Project
The purpose was to create a power supply that could be interchanged from 0V –
(+)15V, and also 0V – (-)15V. The board is created using Eagle, which is the
transferred to a transparent page in order to get the outline of the copper traces on
to the PCB using an ultraviolet light. The board is then populated.
Aims of the Project
The main purpose and aims of the project are listed below:
1) Draw/Create/Design a schematic of the circuit.
2) Fabricate the PCB.
7
Section B
Schematic and Circuit Operation
A schematic is the building block of the project. It shows where all the traces and
components connect to. Given the incomplete circuit, we were given the task to
figure out what components went where, and which way they were supposed to
face. Below in figure 1 is the incomplete schematic.
µ
µ
µ
µ
2.1 Schematic Drawing
µ
Figure 1 – Incomplete Schematic
8
With some knowledge on how the circuit works, and learning the flow of current, we
were able to figure out which way each missing components went. Below in figure 2,
is the complete schematic with all missing components.
Figure 2 – Complete Schematic
9
Operation of the Power Supply
Power rectification
In this section is where the AC voltage is transformed to DC voltage. In figure 3 is the 4
diodes clip the wave form so only a positive or a negative voltage is output. The
capacitors are used to smooth it.
Figure 3 – Power rectification
10
AC-DC Rectification
In figure 4 is the oscilloscope reading of the AC current entering the circuit, and the
DC current after it is rectified through the diodes.
DC
AC
Figure 4 – AC and DC Rectification on Oscilloscope
11
In figure 5, is the circuit of which I got the oscilloscope readings from. Channel A is
reading the AC current. And channel B is reading the DC rectified current.
Figure 5 – AC and DC Reading Circuit
12
Fixed 5V Power Supply
In the final power supply is a 5 V DC supply. It is made of two diodes, one
electrolytic capacitor, and a LM7805 voltage regulator. The two diodes make the
voltage from AC turn into DC. The capacitor will smooth the DC signal. The LM7805
sustains the voltage going to the load at 5V. Figure 6 is the 5 V fixed supply circuit.
XMM5 is reading the 5V.
XSC1
Ext T rig
+
_
B
A
XMM1
+
_
+
XMM2
_
U1
LM7805CT
XMM6
LINE
VOLTAGE
XMM5
VREG
COMMON
XMM3
S2
Key = Space
F1
0.5_AMP
S1
D1
1N4007GP
Key = Space
100Ω
100%
Key=A
C1
2.2mF
V1
T1
120 Vrms
60 Hz
0°
R1
D2
1N4007GP
XSC2
4.1
115/28 Vac 28VA
Ext T rig
+
_
B
A
+
Figure 6 – 5V Supply Circuit
Below is the mulimeter reading. (Figure 7.)
Figure 7 – Mulimeter Reading.
13
_
+
_
Below in figure 8, is the oscilloscope reading showing the smooth 5 V.
Figure 8 – Smooth 5 V DC
14
0-15V Variable Power Supply
This supply is a variable supply shown in figure 9. By switching the position of the slider
on the potentiometer, the resulting change in the resistance will cause the output voltage
of the regulator 2 to change. The position shown below in figure 9, at 100% of 1.5K
Ohm, the output is around 15V. The diode and capacitor on the output in parallel with the
load are a waveform clipper and a filter.
U1
LM117HVH
XMM6
Vin
XMM5
Vout
ADJ
R2
120Ω
S2
R1
Key = Space
D1
1N4007GP
C3
10µF
D2
1N4007GP
D8
1N4007GP
C1
2.2mF
Vac 28VA
D3
1N4007GP
D4
1N4007GP
D6
1N4007GP
C2
2.2mF D7
1N4007GP
R4
1kΩ
R3
1.5kΩ
100%
Key=A
Figure 9 – 0V-15V Variable Supply at 100%
15
100Ω
100%
Key=A
Shown below in figure 10 is the mulitmeter reading of XMM5. The reading is with
the 1.5K Ohm potentiometer at 100%.
Figure 10 – Multimeter Reading with Pot at 100%
16
ac 28VA
The position shown below in figure 11, at 0% of 1.5K Ohm, the output is around 0V.
In figure 11 is the 1.5K Ohm potentiometer set at 0%.
U1
LM117HVH
XMM6
Vin
XMM5
Vout
ADJ
R2
120Ω
S2
R1
Key = Space
D1
1N4007GP
C3
10µF
D2
1N4007GP
D8
1N4007GP
C1
2.2mF
D3
1N4007GP
D4
1N4007GP
D6
1N4007GP
C2
2.2mF D7
1N4007GP
R4
1kΩ
R3
1.5kΩ
0%
Key=A
Figure 11- 0V – 15 V Variable Supply at 0%
17
100Ω
100%
Key=A
Shown below in figure 12 is the mulitmeter reading of XMM5. The reading is with
the 1.5K Ohm potentiometer at 0%.
Figure 12 – Multimeter Reading with Pot at 0%
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REG2
LM117HVH
XMM5
Vin
Vout
ADJ
0-15V Variable Power Supply
(Negative)
XMM6
R2
120Ω
SW2 Key = Space
R5
1N4007GP
680Ω
D1
D2
As shown above, which is the 0-15V positive power supply, the circuit made had a
1N4007GP
Load1
negative supply as well. Show below is theC3circuitry
for
R7 the negative supply in figure
D8
10.0kΩ
10µF
C1
100Ω
100%
Key=A
2.2mF
13. By switching
the position of the potentiometer, the resulting
change in resistance
MM4
1N4007GP
D5
1N5232B
will cause the output
voltage to decrease and increase.
C5
10µF
D6
1N4007GP
1N4007GP
D3
D4
C2
2.2mF
D7
1N4007GP
5
1
7
U4
3
1N4007GP
6
R4
1kΩ
2
UA741CD
4
R3
2kΩ
70%
Key=A
R1
220Ω
3
2
REF
VIN VOUT
R6
10.0kΩ
1N4007GP
C4
D9
10µF
1
VREF
U11
LM337
XMM7
Figure 13 - 0-15V Power Supply Circuitry (Negative)
Shown below in figure 14 is the reading of XMM7. This multimeter is reading the
output of the LM337 (or the negative regulator).
Figure 14 – Mutlimeter reading at the Output of LM337
19
The Op Amp
The larger number of components in this negative portion is due to the fact that this
tracks the output of the positive regulator and makes sure the output of the negative
regulator is equal in scale. The capacitor C4 and the diode D9 work the same as the
LM317 (positive 0-15V). The resistor R7 works the same as R2 in the LM317. It allows
the regulator to compare voltages at the output and the without creating a short. Pins
4 and 7 of the Op Amp are the negative and positive, or power to the Op Amp.
Op Amps can be used essentially in two modes: as an amplifier, as suggested by its
name; secondly, it can be used as a comparator. Using the Op Amp as a comparator
means that the input at pins 2 and 3 are constantly being compared. These changes are
always the result of a change in voltage at pin 2 since pin 3 is connected to common.
The voltage at pin 2of the Op Amp is the same as where resistors R5 and R6 are
connected. This connection forms a voltage divider between two resistances of the
same value.
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Section C
Printed Circuit Board
Using Eagle the actual circuit board was made. Using the route command, you can
join certain components together. In eagle you can use jumpers to go over a trace
that cannot be crossed with another one. Jumpers are used to avoid shorts.
Eagle Schematic
Show in figure 15 is the Eagle schematic of the circuit. This was built before routing the
PCB. You needed to ensure all your connections were wired correctly in the schematic to
ensure the routing of the PCB would work correctly.
Figure 15 – Eagle Schematic
21
Printed Circuit Board Layout
Shown below in figure 16 is the complete Eagle board. Made from the schematic, you
needed to place all the components onto the board and route them. The red box to the
right of the picture is the heat sink. The red signifies that it is something on the top of the
board. The blue traces are routes (copper) which are on the bottom of the board. The
green squares on the board are called jumpers. As stated before use jumpers are sued to
go over a trace that cannot be crossed with another one and they are used to avoid
shorts.
Figure 16 – Complete Eagle Board
22
Below is the board with the copper pour on it. The large blue areas are called the ground
plane. The ground plane is used to connect or attach all the components that are supposed
to be connected to ground. The ground plane makes routing easier. It is shown below in
figure 17.
Figure 17 – Eagle with Copper Pour
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Printed Circuit Board Production
Step 1: Image Transfer to PCB from Digital Negative
The first step taken was to place the transparency we got printed onto the board. It
was placed face down onto the UV light, and turned on for 60 seconds. It was a
negative of the board, so, where the light went through the transparency, it was
hardened onto the PCB. This is where the traces of the board will stay.
Step 2: Photo Developer Machine
This is the second step which will wash away photo sense material that didn’t get
exposed to the UV light. It was put into the tank for 2 minutes and 30 seconds. The
board was screwed onto a bracket, which was lowered into the tank to get rinsed.
Once it has been washed with chemicals, it is rinsed off with water.
Step 3: Etchant Tank
The etchant tank will remove the copper that is not needed on the board. It uses a
high temperature. It was similar that we put the board into a bracket and lowered it
down into the tank. It was timed for 2 minutes and 30 seconds as well. Once the
process in the tank is complete, it is also rinsed.
Step 4: Removal of Photo-Resist from Traces
At this stage, the board will have all the copper traces that you wanted on your
board. To remove the cured photo-resist material, the board had to be put into a
small bath of Sodium Hydroxide. Once put into the chemical, all the photo-resist
material would simply fall off of the board. Once all the photo-resist was removed,
all the traces were completed and clearly visible. It was then rinsed with water and
the dried.
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Step 5: Drilling Holes in PCB and Heat Sink
Next, all the holes had to be drilled into the board. The Op Amp was drilled with a
1/32” hole, the component holes were all drilled with a 3/64” drill, and lastly, the
three heat sink holes and the regulator holes in the board were drilled which were
5/32”.
Step 6: Trimming Board to Final Size
The final step was to trim the board to the final desired size. We used a sheer to cut
it to size. You had to be careful not to cut off any of the traces on the board.
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Section D
Box Production
Box Drawing
To produce the box, templates were used to punch all the necessary holes. The templates were
glued onto the box and holes were made with a puncher and a drill. In figure 18 are the three
templates used to manufacture the holes.
Figure 18 – All Punching and Drilling Templates
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Box Production
The physical housing for the PCB (the box) was pre made. The holes needed to be punched
into the box with a punch and drill. The drilling/punching templates were provided.
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Box Assembly
The overall production of the box was very difficult. Ensuring perfection and precision was
critical. It was important to follow the instructions that were given. The instructions given
very specifically outlined how to connect every component wire and how to and where to
solder certain hot wires. Below are the insides of the box.
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Final Assembly and Testing
Final Assembly
During the final assembly, all the components and wires were placed according to the
instructions. All wires were soldered onto the correct binding posts. This was a difficult part
because it got a little confusing. During the assembly was when the whole box was finished.
Every last component had to be soldered to the correct area for the board to function in the
box. To get the box to function out of the box was much simpler than getting the PCB to
work in the box. Shown below is the front face of the digital display. Shown at 0V and 15V.
Also the power cord and fuse on the back of the supply is shown.
29
Testing
When testing the board, there was troubleshooting involved. Before putting the board into the
box, it was hooked up to a transformer on a lab bench. That transformer supplied the power
to the board. Next, the black pin from a multimeter was connected to the ground wire and the
other red pin alternated from the fixed 5V, to the 0-15 V supply (positive and negative) to
ensure all parts of the board were working. This ensured the right voltages were being output
off the board through the wire. These were the wires that were connected to the binding posts
in the final assembly.
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Summary and Conclusion
Schematic Drawing
We were given an incomplete schematic drawing of the circuitry. It was intended for us to
complete the schematic by putting all the proper components into the circuit correctly. It was
not very difficult considering our knowledge on the topic.
Printed Circuit Board Drawing
In order to produce the actual PCB, the board had to be created in a program to simulate it,
and ensure the circuit operated correctly. The program used was Eagle. It was not the easiest
to use, but it was simple in the sense that it simulated the circuit beautifully. Ensuring all the
proper components were used was crucial to ensure the board worked.
Printed Circuit Board Production
Once the whole board was created on the computer, it was time to make the physical board.
This took many steps (shown above) and was made very easy. It was simple because all the
instructions were given, and all the stations had their own instructions on what to do. While
making the board, you had to be very careful because some things could get ruined easily;
such as coppers traces being torn off the board.
Box Drawing
The actual box that the board was to sit into was given. It was pre made. The only thing that
had to be done was punch and drill all the holes needed. This was done through templates,
which were also given. This saved a lot of time. Even though they were quite simple
drawings, they were a tremendous help in speeding up the power supply production.
Box Production
The box production was basically the final step. This is where all the wires that were hanging
off the board were soldered onto the binding posts. Also, the fuse and display was connected.
With the instructions given, it was an easy task. Following them ensured success. Everything
was laid out for an easy manufacturing.
31
Assembly and Testing
Once the board and all the wires were soldered into position, it was time to make sure it
worked. This included trouble shooting any issues. The board was working perfect when it
was not in the box, but once everything was soldered together, the board was not working. It
was an easy fix. The issue was the ground connection got interrupted. This made the whole
board malfunction with 0V outputting.
32
Appendix A
Incomplete and Completed Schematic Drawing in Landscape
33
34
µ
µ
µ
µ
µ
35
Appendix B
Full Size Eagle Schematic in Landscape
36
37
Appendix C
Inverted Bottom of Board
Non Inverted Bottom of Board
--
38
39
Appendix D
Drilling and Punching Templates
40
41
42
43
Appendix E
Front Face Sticker Template
44
45