20 CHAPTER 3 METHODOLOGY 3.1 Opeartional Flow chart Below by oss17616

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									                                       CHAPTER 3



                                   METHODOLOGY




3.1    Opeartional Flow chart

       Below are the operational flowchart that being develop as to complete all the
process of the succesfull final year project.




                            Figure 3.0 : Operational Flowchart




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3.2    OrCAD software




       OrCAD is a software tool suite used primarily for electronic design automation.
The software is used mainly to create electronic prints for manufacturing of printed
circuit boards, by electronic design engineers and electronic technicians to manufacture
electronic schematics and diagrams, and for their simulation. The name OrCAD is a
portmanteau, reflecting the software's origins: Oregon + CAD. The OrCAD product line
is fully owned by Cadence Design Systems. The latest iteration has the ability to
maintain a database of available integrated circuits. This database may be updated by
the user by downloading packages from component manufacturers, such as Texas
Instruments




3.3    Capture CIS




       OrCAD Capture CIS is a software tool used for circuit schematic capture. It is
part of the OrCAD circuit design suite. Capture CIS is nearly identical to the similar
OrCAD tool, Capture. The difference between the two tools comes in the addition of the
component information system, or CIS. The CIS links component information, such as
printed circuit board package footprint data or simulation behavior data, with the circuit
symbol in the schematic. When exported to other tools in the OrCAD design suite, the
data stored in the CIS also transfers to the other tool. Thus, when a design engineer
exports a schematic to the circuit board layout utility, the majority of the circuit
elements have footprints linked to them. This saves time for the design engineer.
Capture CIS has the ability to export netlists, representative of the circuit schematic
which is currently open, to the OrCAD simulation utility, PSPICE. Capture CIS also
exports a simulation configuration file, accessible through the simulation toolbar. This,



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coupled with the CIS, allows for quick simulations with data representative of how the
circuit will behave. Capture may also export a netlist to the SPICE simulation utility.

       Capture may export a hardware description of the circuit schematic that is
currently open, either in Verilog or VHDL. Capture also has the ability to export netlists
to several different circuit board layout utilities, such as OrCAD Layout, Allegro, and
others. When combined with the CIS, circuit baord footprints are linked to this netlist.
This, combined with the pin to pin interconnect description of the netlist, will open the
correct part footprints, and, if the data that CIS looks up is correct, will connect all of
the pads together with representative lines. This feature makes the circuit board design
process easier for the design engineer.




                           Figure 3.1 : Example of Schematic




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                          Figure 3.2 : Sample of routing board




3.4     Create PCB Board


3.4.1   Preparing the artwork/design


        Firstly design the required circuit. The best option is to design the circuit on a
computer by using orcad software or ect. Generate gerber data from software and by
using the data we can get cnc drill and film format.


3.4.2   Film processing


        From gerber data we can generate an exact film representation of our design. We
will create one film per layer. In our lab we use ptotoplotter to process a film.




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                          Figure 3.3 : Photoplotter Station



i)    Lift the photoplotter lid, place film on the drum fix it by masking tape along the
      top and bottom edge. Rotate the drum back to its initial position and close the
      lid.
ii)   After photoplotting film complete, in dark green light, open the lid and remove
      film. Process film immediately by using developer and fixer chemical.




      Figure 3.4 : Film process Station                  Figure 3.5 : Film




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3.4.3 Drill raw material




                           Figure 3.6 : CNC Drilling Machine


        For this final year project we use 1.5mm thick 450X305mm copper clad single
side board. Before we divide it into several cavities, exported excellon drill file from GC
CAM or ISOCAM and drilling PCB board using Route Pro2000. After drilling process
finished, go to another step.




             Figure 3.7 : (a) Before drilling,              (b) After Drilling



3.4.3   Clean / Brush and drying process

   i)      After drilling process finished, take out PCB bard from drilling machine and
           wash the board under tap with scotch bride




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ii)       Put PCB board through a brush cleaning machine, make sure copper clad on
          top before input
iii)      Repeat process (ii) until PCB board clean and free from finger print.
iv)       Finally, put PCB board through a bench top drying machine for drying
          process.
v)




       Figure 3.8 : Brush cleaning machine     Figure 3.9 : Drying machine




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3.5 Flow Chart for PCB making



           Dry Film Laminator                             UV Expose &
                                                           Developer




                                Developer Machine



                                 Etching Machine




                                Photoresist Stripper




                                 Hot Air Plantting



                                       FINISH



3.5.1   Apply Dry Film




             Figure 3.10 : Laminator                 Figure 3.11 : After laminated


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3.5.2   UV Exposure Process




Figure 3.12 : Laminated PCB with film   Figure 3.13 : Vacuum exposure unit



3.5.3 Developer Process




   Figure 3.14 : Developer Machine      Figure 3.15 : After Developer




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3.5.4 Etching Process




       Etching Machine                           After etched



     Figure 3.16 : Etching Machine                 Figure 3.17 : After etched




3.5.5 Photoresist Stripper




     Figure 3.18 : Photoresist Stripper Tank   Figure 3.19 : After stripper




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3.5.6 Hot Air Platting




      Figure 3.20 : Hot Air Platting Machine              Figure 3.21 : After Platting



3.6    Experimental testing (main circuit)


       Below is the AC voltage controller circuit that being used in this final year
project and being tested at Kg Wai Labarotary:



          Test point # 1        Test point # 2           Test point # 3        Test point # 4




            Regulator             Triggering/Driver         Isolated          Snubbers
                                       Circuit            transformer

                         Figure 3.22 : AC voltage controller circuit




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3.7    Experimental results (waveforms)



       Below are the results gained after completing the experimental testing:




Figure 3.23 : Voltage across the load           Figure 3.24 : Voltage Anode to Cathode




                        Figure 3.25 : Waveform at the UJT gate



       When current flows through UJT, it will flows through the UJT, it will flow
through the primary side of the transformer. The transformer will provide the insulation
as it produces a pulse in its secondary coil. The seconadary coil of the pulse transformer
is connected to the gate of the SCR. The SCR is connected so that it controls current
flow trhough the bridge rectifier. This main circuit is designed so that the SCR will see
only pulsing DC voltage, and the load will see the complete AC voltage sine wave.
Since the SCR sees the positive and negative half-waves as rectified positive pulses, it


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can control the 360° of the original AC supply voltage. The circuits uses the feature of a
bridge rectifier that current will flow in the AC side of the circuit anytime current in
flowing in the DC side of the bridge rectifier. Since the SCR can easily control the DC
current, it will indirectly have control over the current in the AC side of the circuit. This
type of circuit was popular before larger triacs were manufactured. Now, the triacs are
avaiable in larger sizes, they would be used in this type of control circuit.




3.8    Experimental set-up
       The efficiency of a single phase transformer is measured by comparing the
output to input power directly. To achieved this final year project objectives, there are
sveral method done. The other method which is normally used is by measuring the core
loss and copper loss separately. In this project, the direct and indirect testing are done.
For the direct testing, the Schaffner equipment is connected with the transformer,
harmonic analyzer and single phase induction motor as load. While for the indirect
testing, the Schaffner equipment is connected with the AC voltage controller circuit, two
harmonic analyzer (input and output reading), transformer and single phase induction
motor as load. Schaffner equipment is use for measuring which is a substitution of
voltmeter and wattmeter and also can be used for open test and short circuit test.


The experimental set-up are conducted in two ways chich is direct and indirect testing
and as in Figure 3.26 and Figure 3.27 below:


       i) Direct testing




            Schaffner                                         Harmonic
            equipment                                         analyzer
                                                               PM100
                               Transformer under
                                      test                                      Single phase motor
                                                                                      (load)


                       Figure 3.26 : Blockdiagram of direct testing


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  ii) Indirect testing




                           Harmonic analyzer           Harmonic analyzer

                     AC            PM100
Schaffner                                                     PM100
                   voltage            1
equipment                                                        2
                  controller       (input)                    (output)

                                             Transformer under
                                                    test           Single phase motor
                                                                         (load)


                 Figure 3.27 : Blockdiagram of indirect testing




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