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Final Project

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									                                              Final Project

                                           Jason A. Wilson*
                         Electronic Circuits and Devices Laboratory (EE401)
                            College of Engineering and Computer Science
                                       Wright State University
                                         Dayton, Ohio 45435

                                                  ABSTRACT

Within this report, you will find various data regarding the final project given in class. Along with the
circuit analysis, you will see the circuits designed for our needed purpose. Some of the value collected is
that the motors receive there needed 3 volts to operate, and the solenoid receives its 8.97 volts. You will
also view the use of various electrical components i.e. light emitting diodes, bi-polar junction transistors
etc.

                                             1. INTRODUCTION

At the beginning of this project, we were given the option to work in groups or individually. I had decided
to work as a group in order to build a more complex system of electrical and mechanical system. We had
to include the components that the instructor had handed out, which you can view the list along with other
components added to the circuit in table 1.

 1 Dip switch
 3 741 Operational Amplifiers
 3 2N3055 Bi-Polar Junction Transistors
 6 Photo Cells
 6 Light Emitting Diodes
 1 1MΩ Resistor with a 5% tolerance
 1 820Ω Resistor with a 5% tolerance
 6 10Ω Resistors with a 5% tolerance
 1 560Ω Resistor with a 5% tolerance
 4 Circuit boards
 22 AWG hook up wire
 2 1.5-3 Volt dc motors
 1 Solenoid
 Speaker wire
Table 1

1.1 741 Operational Amplifier (op-amp)
The operational amplifiers were initially designed to aid in mathematical problems, which involves
integrating and differentiating. When the voltage is higher on the negative input, then you will drive the
output to the negative Vcc. When the voltage is higher on the positive input, the op-amp will be driven
toward the positive Vcc.

1.2 2N3055 Bi-polar Junction Transistor (BJT)
The bi-polar junction transistors have come a long way since the early 1900’s. When at first used to be a
combination of vacuum tubes now is comprised with two different types of material, the n type and the p
type. Today the BJT’s are used in a variety of components. When a current I b enters into the base of the

*
    Wilson.97@wright.edu; phone 1 937 776-5355; submitted for grade on January 22, 2004
transistor, it allows even more current Ic flow through the transistor while both Ib and Ic flows out of the
transistor through the emitter as Ie.

1.3 Photoconductive Cells
A photoconductive cell is a resistor that varies with the amount of light, which is being absorbed by the
component. With a lot of light on the photoconductive cell, the resistance will theoretically be zero, and
without any light, the resistance should be infinite.

1.4 Light Emitting Diodes (LED)
A LED is a special diode that emits light when it is connected to a power source. There are many
advantages in using an LED, which includes very low operating voltages and a low current draw. This
makes them very useful in electrical components, such as power on lights and now making there way into
the automotive industry.

1.5 1.5-3 Volt DC Motors
A dc motor is comprised of many different parts that when they work together produce a rotating motion of
a shaft. When the power enters, the motor is connected to two different brushes, which then is connected to
different electromagnets. When these electromagnets are energized, the try to connect with there opposite
counterpart that produces the rotating motion on the shaft.

1.6 Solenoid
A solenoid is a simple device that uses electromagnetic forces into usable motion for various devices. A
solenoid is made up of a long wire that is wound to make a cylinder. When current is applied to the coil of
wire, it produces an induced magnetic field that pulls a rod made of some ferrite material into the coil.

1.7 Resistor
A resistor is a device that is very necessary to any electrical component. The purpose of a resistor is to
resist current causing a reduction in voltage. There are many different values of resistors and in table 2;
you can view a resistor value chart.

 1st Digit        2nd Digit       Multiplier   Tolerance
 0 Black          0 Black         x1           5% (Gold)
 1 Brown          1 Brown         x10          10% (Silver)
 2 Red            2 Red           x100         20% (none)
 3 Orange         3 Orange        x1K
 4 Yellow         4 Yellow        x10K
 5 Green          5 Green         x100K
 6 Blue           6 Blue          x1M
 7 Violet         7 Violet        x10M
 8 Gray           8 Gray          x100M
 9 White          9 White         x1000M
Table 2

                                                2. THEORY

The whole purpose of this design is to raise up a Budweiser sign made of plexus glass. First, when the
lights are turned on, it should allow a small amount of voltage flow through the photoconductive cell and
into the positive input terminal of the op-amp. This results in the output of the op-amp being, that of the
positive Vcc, which allows the BJT transistor to open and allow the current to flow. This will let the
solenoid pull in and let a ball bearing roll down a track. At the bottom of the track, the ball bearing falls
and hits a lever, which taps a matchbox car allowing it to roll down a track and flip a switch. That switch
then allows the current to flow through the photoconductive cells and into the op-amp. With the voltage
leading into the op-amp, it is driven toward the positive Vcc. This allows some current to flow into the base
of the BJT, thus allowing current to flow through the motor and the BJT. This motor is then connected to a
fan, which increases the airflow in a directed path. This increase in airflow pushes a switch closed which
powers the final part of the system. With this switch on, the current flows into the positive side of the op-
amp driving the output to the positive Vcc, and through resistors to the LED’s in the plexus glass sign.
Then the voltage flow through another photoconductive cell then continues onto the base of the BJT. On
the other side of the photoconductive cell is an LED, which lights up and reduces the resistance of the
photoconductive cell allowing current to flow into the base of the BJT. With the current flowing into the
base, this allows the current to flow through the BJT and thus allowing the motor the turn on. With this
motor on, it will turn some gears and lower the sign so that you may read Budweiser. When the sign is
upright, a piece of black plastic will block the LED’s light from reaching the photoconductive cell and thus
stopping the current from entering the base of the BJT.

                                                 3. DATA/RESULTS

In this section of the report, you will find the circuit schematics, the circuit analysis, and the results of our
analysis. To start out with we will look at the circuit schematics, which entails breaking it down into
several different circuits that you can view in figure 1.



                                                                                    +
                                                                             7.8        9V
       +                 117k                     U1A
           3V                                +   UA741 820
                          1.2k                                                Q1
                                                                             NPN

                           Circuit A
                                                   U2
                                                 UA741
                                                                     Motor
                                                                     2.5
                +                117k        +
                    3                                                    Q2
                                                                       2N3055
                                 1.2k
                                Circuit B


                                                                                     D1
                                                                             M1     LED1
                                                                             2.5
                                                  U1A
           +             1M
                                            +    UA741     1k
               3V                                                          Q1
                         1.2k                                             NPN


                    10          Circuit C
                    10
                    10
                    10
                    10
                                       D1          D2            D3           D4      D5            D6
   +                10                LED1        LED1          LED1         LED1    LED1          LED1
       6
                                                         Circuit D

Figure 1

In figure 2, you can view the circuit analysis for circuit A.
With out any light there will be no operation of the circuit.
V1 Vop                    3V 0V
               Iop                   26 A
   117 k                 117000
V1 Vop                   3V 0V
               Iop                   2.5 mA
   1.2 k                  1200
More current flowing into the non inverting terminal of op
 amp drives the output to                 Vcc
Therefore, Vo         3V              100
                       9V                        9V
       Vo        Vb   7.8       3    Vb         7.8
Vb                                                     Vb       6.46 V
        820                     820             100
       Vo Vb          3V     6.46 V
Ib                                        11.5 mA
           820         820
Ic          Ib    100 11.5 mA        Ic     1.15 A
Vc    1.15 A 7.8            8.97 V
Therefore, the voltage across the solenoid is 8.97 V and the
 current is 1.15 A making the power dissipated be 10.32 Watts
Figure 2

In figure3, you can view the circuit analysis for circuit B.

Without any light there will be no output of the circuit.
V1 Vop                   3V 0V
               Iop                  26 A
   117 K                 117000
V1 Vop                   3V 0V
               Iop                  2.5 mA
   1.2 K                  1200
More current flowing into the non inverting terminal of op
 amp drives the output to                 Vcc
Therefore, Vo 3 V         100
      V1     3V
Ic                  1.2 A
    2.5     2.5
    1.2 A   1.2 A
Ib                  12 mA
             100
Vc 1.2 A 2.5      3V
Therefore, the voltage across the motor is 3 V and the current
 is 12 mA making the power dissipated be .036 Watts
Figure 3

In figure 4, you can view the circuit analysis for circuit C.


With out any light there will be no operation of the circuit.
V1 Vop                    3V 0V
               Iop                    3 A
    1M                   1000000
V1 Vop                   3V 0V
               Iop                   2.5 mA
   1.2 k                  1200
More current flowing into the non inverting terminal of op
 amp drives the output to                 Vcc
Therefore, Vo            3V              100
                          3V                     3V
         Vo    Vb        2.5        3    Vb     2.5
Vb                                                     Vb       9V
         1000                       1000        100
        Vo Vb        3V        9V
Ib                                      12 mA
        1000         1000
Ic        Ib     100 12 mA          Ic     1.2 A
Vc      1.2 A 2.5          3V
Therefore, the voltage across the solenoid is 3 V and the
 current is 1.2 A making the power dissipated be 3.6 Watts
Figure 4

In figure 5, you can view the circuit analysis for circuit D.

           1         1          1         1        1     1       1
Req                                                                    Req    1.667
         10         10         10        10     10     10        Req
Vi      6V
Vr      3.77 V
VL      2.23 V
Figure 5

                                                   CONSLUSION

Designing various circuits takes time and patience, along with the knowledge of some computer software,
such as Circuit Maker. This enables us to build the circuit and test to see if it will work or not. From this
knowledge, we concluded that the circuits above were applicable for our purpose. From this we concluded
that transistors can be used as a simple switch or it may be used as a power amplifier as seen in circuit A.
This project had given me some experience that will aid me in mechanical designs in the future. Since I
now know that there are strict limitations on certain devices is am able to work around them. Within this
system of electrical and mechanical devices, there was a great deal of reconfiguring certain areas through
experimentation. By the completion of this system, I have come to the conclusion the this system would be
know as the rube Goldberg, meaning accomplishing by complex means what seemingly could be done
simply.
                                                REFFERENCES

1.   G. Power, Lab requirements, www.cs.wright.edu/people/faculty/gpower/ee401.htm
2.   Boyleslad, Robert L., et al. Electronic Devices and Circuit Theory. Columbus: Ohio, 2002.
3.   G. Power, Supplemental Motor Notes, www.cs.wright.edu/people/faculty/gpower/ee401.htm
4.   ON Semiconductor, Complementary Silicon Power Transistors, http://onsemi.com

                                           ACKNOWLEDGEMENTS

1.   W. Earick, Lab TA, E-mail Earick.2@wright.edu
2.   K. Jurich, Lab Partner, E-mail kat-jurich@hotmail.com
3.   D. Duff, Lab Partner, E-mail duff.11@wright.edu
4.   G. Power, Instructor, E-mail gpower@cs.wright.edu
           Final Project



      Rube Goldberg design



Electronic Circuits and Devices (EE401)




          Name: Jason Wilson




      Submission Date: March 8, 2004

								
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