https://goo.gl/8Yt89Q

LOGIC CIRCUIT

I.                    Introduction

We are now in the world of modernization. In fact, almost everything that surrounds us is attached to technology. We can’t even imagine our whole day without a glimpse of our facebook and visiting our favorite social networking sites. Computers are now part of our day to day living. Before the words of our messages will reflect into the monitor, the computer will first interpret them. If you will try to open the computer, you will seevery complex connections of wires and other electrical devices that are called logic circuits.

Logic circuits are considered to be the foundation of this world of computers and logic gates are the building blocks of these.

II.                  Definition

When we talk about digital logic circuit, this is a circuit that only handles two information or binary signals which are one (1) or zero (0).  Example of a digital logic circuit is a computer which is constructed with many types of basic circuits called gates.

Logic Gate is the basic type of digital electronic circuit.

III.                    Types of  Logic Gates

             1.       AND gate. This is a type of electronic circuit that will yield a high output or 1 if all inputs are also high.

http://goo.gl/8RVxE5

                                                      

2.       OR gate. This is a type of electronic circuit that will yield a high output if there is at least one high input signal.

http://goo.gl/8RVxE5

                                         


3.       NOT gate. This is a type of electronic circuit that will have an output that is the inverted version of the input.

http://goo.gl/8RVxE5

                                                              

4.       NAND gate. This is a gate that is NOT-AND gate. The outputs will be high if there is at least one input that is low.

http://goo.gl/8RVxE5

5.       NOR gate. This is a combination of a NOT gate and an OR gate. The output signal will be low if any of the two inputs is high.

http://goo.gl/8RVxE5

                                      

               6. EXOR gate. This is known as Exclusive-OR gate which will yield a high output if there is only one high input.

http://goo.gl/8RVxE5

                                                





7. EXNOR gate. This is what we call Exclusive-NOR gate which is actually the opposite of the EXOR. It will give a low output if there is only one high input.

http://goo.gl/8RVxE5

                                                  

IV. Network Logic Gates

V. References

Retrieved on October 31, 2015 at http://www.ee.surrey.ac.uk/Projects/Labview/gatesfunc/#introduction

Retrieved on October 31, 2015 at http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Comb/gates.html

http://goo.gl/uzj65X

TRANSISTOR

I.                    Introduction

It is amazing to know how our brain works. It could do multiple tasks for every single second of our life. Because of its very complex work, it comprises billions of brain cells which are known as neurons. In the world of technology, computers are associated to our brain in which behind its operation is also billions of electrical components that work together. These are resistors, capacitors and transistors. Since we have learned already about the first two electrical components, we will now study about transistors.

Transistor is a three-leg electrical component that makes it unique from the rest. It functions as an amplifier or a switch.  It is a bipolar junction which consists of three layers of doped semiconductor which is usually made of silicon and is even considered as the fundamental composition of integrated circuit.

II.                  Parts

https://goo.gl/BovwEU

As mentioned earlier, a transistor has three legs. To understand the function of the three legs, let’s associate it with a faucet. In a faucet, there is the path where water enters and leaves though it is somehow just a one path. As observe in the faucet, there is a valve that controls the volume of water that will flow.

III.                    Types

A.      Bipolar Junction Transistor

This is a type of transistor having 3 legs or regions known as the base, the collector, and the emitter. Unlike FET transistors, the other type, this transistor is a current-controlled device because small current that enters in the base region of it can cause a tremendous increase of current flowing from the emitter to the collector region. This is the only transistor that is turned on by inputting current in the base because of its low impedance or resistance. This is also the reason why BJT can amplify the most.

http://goo.gl/lju7qm

A.1. Types of Bipolar Junction Transistor

a. NPN. This is a transistor that has two n-type semiconductors, the collector and the emitter, with p-type semiconductor as the base separating them. The electrons are the major current carrier of this transistor.

https://goo.gl/yWp6o9

b. PNP. This is the opposite of NPN. This consists of two p-type semiconductors and one n-type separating the two. In this type, the electrons are the minority current carrier. Hence, the holes are the major current carrier of it.

https://goo.gl/vv735K

B.      Field Effect Transistor

1. a. JFET has lesser impedance than MOSFET.

1. b. MOSFET has higher impedance than JFET.

This has other names of its three legs or regions which are gate, source and drain. If BJTs are current-controlled devices, FETs, on the other way around are voltage-controlled devices. It means that a voltage applied in the gate controls the flow of current from the source to the drain regions. FETs have high impedance causing little current through it making it to produce less amplification than the BJT. But the good thing here is it can cause less loading in the circuit compared to BJT and they are considered to be cheaper and easy to make.

      

                   C.      Other types according to Function

C.1. Small Signal Transistors are preferable to use in amplifying low-level signals which also functions as switches.

http://goo.gl/2yKbFk

C.2. Small Switching Transistors are primarily made as switches but can also be used as amplifiers but not as capable as the small signal transistor.

http://goo.gl/2yKbFk

C.3. Power Transistors are best used when large values of current and voltage are used. These come in NPN and PNP forms.

http://goo.gl/2yKbFk

IV.                    Functions

1.       Amplifier. Small amount of current enters to one leg and as it leaves, it becomes bigger current. In other words, it multiplies the input current. In this case, common applications are hearing aids, microphone and speakers.

2.       Binary switch. Same manner in amplification where small amount of current flows in one part and it becomes bigger as it flows to the other part. These small current will switch on the bigger one. So in a microchip, billions of transistors can be switched on and off and these san store two numbers, zero for off and one for on. All transistors can store different numbers or letters individually that are known as characters.

V.                  References

Retrieved on October 31, 2015 at http://whatis.techtarget.com/definition/transistor

Retrieved on October 31, 2015 at http://hyperphysics.phy-astr.gsu.edu/hbase/solids/trans.html

Retrieved on October 31, 2015 at http://www.technologystudent.com/elec1/transis1.htm

Retrieved on October 31, 2015 at http://boysdad.com/archives/3633

Retrieved on October 31, 2015 at http://www.learningaboutelectronics.com/Articles/Types-of-transistors.php

https://goo.gl/JnWOlN

Integrated Circuit

I.                    Introduction

Each body part serves its very own purpose. Pair of eyes is for seeing, pair of ears is for hearing, one tongue is for tasting and many other parts. But try to imagine, can your pair of eyes alone understands what itsees? Or let’s try to reverse my question. Can you understand the happening in the environment if your pair of eyes is not functioning? Maybe for some instances you will but it will be difficult for sure. All information that are being sent by your senses are used and analyzed in our brain. In other words, our brain will summarize all the information before we can decide what will be our response. This is now the highlight of this paper where the same manner is applied in electronics.

At last! We come up to this part. In our previous lessons, we have acquainted ourselves with the different electrical components namely resistor, capacitor and transistor. Each component serves its very unique purpose and if we put them all together, a great function will be made. Integrated circuit is the integration of all the electrical components to serve one goal functioning as one.

               II.  Definition

Integrated circuit or also known as IC is a type of circuit containing millions of resistors, capacitors and transistors. It is a circuit itself but it must still be placed in a circuit to function. Best example of an IC is a microchip. The brilliant persons behind this amazing integration are Robert Noyce and Jack Kilby.

               III. Inventors

Jack Kilby and Robert Noyce

https://goo.gl/qbicV6

IV. Types

1.       Analog or Linear Integrated circuit

https://goo.gl/whlvH6

For a continuous output signals, this type of IC is the answer.  This is considered as more useful than the other type of IC. It is manufactured as less expensive chips but still been useful for more than 40 years. This is the type of IC in most types of amplifiers. This is preferable to use if we desire to have variation of signal outputs of audio-frequency and radio-frequency.

2.       Digital Integrated circuit

https://goo.gl/XmZcj7

As the opposite of the first type, this type does not give continuous output signals. This will only operate at certain states where its building blocks are logic gates since there are only two signals of it, either 1 or 0.

V. Applications

1. Calculator     

https://goo.gl/7OlNAs

2. Digital Clocks/Timers

https://goo.gl/mm1ANu

3. Amplifiers

https://goo.gl/eAUT0K

VI.                    References

Retrieved on October 22, 2015 at http://www.brighthubengineering.com/commercial-electrical-applications/65297-what-is-an-integrated-circuit-theory-and-types/

Retrieved on October 22, 2015 at http://www.computerhistory.org/revolution/digital-logic/12/281

Retrieved on October 22, 2015 at  http://whatis.techtarget.com/definition/linear- integrated-circuit-linear-IC

https://goo.gl/X1igBs

SEMICONDUCTORS

 “Nobody is perfect!” A very famous line uttered by everyone to defend oneself when he/she got mistaken. Same with the things around us, they are not also perfect. Especially in the field of electronics in which there are a lot of available materials that can be used but their conductivity differs and this conductivity would be the consideration in choosing them or not.

                After reading this paper, you will learn about semiconductor, some semiconductor substances,  types of semiconductor,  the process undergone by semiconductors to increase its conductivity and its application in the field of electronics. 

I.                    Nature of Semiconductors

As what its name suggests, it is a material that has a conductivity that falls between a conductor and an insulator. If we try to review, conductor is a material whose ability to conduct electricity is very high and insulator, on the other hand, has very poor conductivity or has very high resistivity. From its prefix “semi”, it means “half” or “partial.” Semiconductors are usually made of germanium and silicon which are known to be good semiconductors.

II.                  Some semiconductor substances

1. Indium

https://goo.gl/8iUmZL

2. Silicon

https://goo.gl/p2XwY7

3. Germanium

https://goo.gl/scih0R

III.                    Types of Semiconductors

1.       Intrinsic semiconductors

In layman’s definition, this type of semiconductor is innately semiconductor in form. In higher aspect, it is defined as a material whose number of holes is the same to the number of electrons.

2.       Extrinsic semiconductors

This type of semiconductor is the advanced intrinsic one. Meaning, extrinsic semiconductors are just intrinsic semiconductors which undergone a certain process called doping. This process is undergone to increase the conductivity of a semiconductor specifically the intrinsic one. The process of doping can produce two types, the n-type and p-type.

2.a. N-type

N-type semiconductor has many free electrons and these electrons are called majority carriers. 

Let’s have silicon as our example here. If silicon is doped with phosphorus, it becomes an n-type semiconductor since phosphorus will contribute electrons instead of holes. In this case, there are already free electrons that will help generate electricity. In this case, phosphorus will be called an n-type impurity since it will make silicon as a n-type semiconductor.

https://goo.gl/6pLIOV

                       2.b. P-type

P-type semiconductors have more holes than electrons. In this case, its majority carriers will be the holes instead of electrons.

                    

In the other way around, if Silicon will be doped with Boron, it will become a p-type semiconductor since Boron will contribute holes.Hence, boron will be called also as p-type impurity since it will make Silicon as a p-type semiconductor.

https://goo.gl/hqZh4j

IV.                    Application of Semiconductors

Semiconductors are widely used in the field of electronics since conductivity can be controlled or manipulated unlike the real high conductive materials. If that is the case, desired voltage outputs and currents can be achieved.

V.                  References

Retrieved on October 20, 2015 at http://whatis.techtarget.com/definition/semiconductor

Retrieved on October 20, 2015 at http://www.brighthubengineering.com/diy-electronics-devices/41694-n-type-and-p-type-semiconductors/

Retrieved on October 20, 2015 at http://www.radartutorial.eu/21.semiconductors/hl07.en.html

                       
                       

Diodes

                                                                DIODES

I. Definition:

         Diodes are known to be a circuit element that allows current to pass through but in one direction only. Meaning, diodes have polarity that cannot be reversed. Its polarity is considered and its main task is to block opposing current. This protects devices when the voltage source is connected in a wrong way. Most of the diodes are made with semiconductors like germanium and silicon.

II. Parts:  

Cathode is the positive terminal of a diode and anode is the negative which is generally shorter than the cathode.



III. Types:

1. Light Emitting Diode (LED). From the name itself, it is a light diode which produces light as current pass through it. This is the one used in series lights because of its colorful light.

https://goo.gl/st9nbr

2. Schottky Diode. This is a type of diode which has very low voltage drops which fall between 0.15-0.4.

https://goo.gl/XVLdLg

3. Laser Diode. A type of diode that produces a focused or pointer light that can be found in the drivers of electronic devices like DVD and CD.

https://goo.gl/WmfjuY

4. Avalanche Diode. This type is preferable to use in high voltage connection and can breakdown without damaging when voltage is connected in reverse.

https://goo.gl/upyOsh

5. Photodiode. Made of p-n junction that works in reverse bias. This type of diode detects light.

https://goo.gl/CWLS4k

6. Varactor Diode. Same with photodiode, it is made with p-n junction thai is also named as varicap diode.

https://goo.gl/RxoCkN

7. Rectifier Diode. As the name itself, it corrects alternating power fluctuations produced in voltage sources.

https://goo.gl/IczszB

8. Zener Diode. A type of diode mainly used for voltage maintenance.

https://goo.gl/fxlTGh

IV. Laboratory Experiment

                                            

                                           Light-Emitting Diodes

A. Objectives:

At the end of this experiment, students are expected to

1. define diodes in their own words

2. identify the types of diodes and their uses

3. enumerate some practical applications of diodes

B. Materials

1. AC-DC Converter

2. LEDs

3. Breadboard

4. Multi-tester

C. Procedure: 

1. Set up circuit having light emitting diodes in the breadboard connected in series connection.

2. Manipulate the voltage output and get the voltage drop in each of the diodes.

3. Record the data using a table.

4. Set up the light emitting diodes in the breadboard in parallel connection.

5. Regulate the voltage output and get the voltage drop in each of the diodes.

6. Record the data in the table.

     D. Data

               

         SERIES CONNECTION

	Voltage drop, V					Current, I
	V1	V2	V3	V4	V5	I1	I2	I3	I4	I5
8.0V	0.4V	0.4	0.4V	1.2V	0.4V	N.D.	N.D.	N.D.	N.D.	N.D.
9.8V	1.8V	1.6V	1.6V	2.8V	1.8V	0.5mA	0.5mA	0.5mA	0.5mA	0.5mA
13.0V	2.2V	2.0V	2.0V	3.0V	2.2V	40 mA	40 mA	40mA	40mA	40mA
16.0V	3.8V	2.8V	2.6V	3.2V	3.0V	145mA	145mA	145mA	145mA	145mA

        PARALLEL CONNECTION

VOUT	Voltage drop, V					Current, I
	V1	V2	V3	V4	V5	I1	I2	I3	I4	I5
2.8V	2.7V	2.7V	2.7V	2.7V	2.7V	N.D.	N.D.	N.D.	N.D.	N.D.
4.0V	3.7V	3.7V	3.7V	3.7V	3.7V	N.D.	N.D.	N.D.	N.D.	N.D.
6.6V	6.5V	6.5V	6.5V	6.5V	6.5V	N.D.	N.D.	N.D.	N.D.	N.D.
8.6V	8.5V	8.5V	8.5V	8.5V	8.5V	N.D.	N.D.	N.D.	N.D.	N.D.
12V	11.9V	11.9V	11.9V	11.9V	11.9V	N.D.	N.D.	N.D.	N.D.	N.D.

Observations:

        I have observed that as the this type of diode produced light, there were voltage drops measured. In series, voltage drops in every diode in not the same and it can be justified theoretically. In the other way around, in parallel circuit it is already the voltage drops that are the same throughout the circuit. If one diode is connected in reverse, there was no current and voltage readings in series connection but in parallel the one that is connected in reverse will the only that will not light. The rest will not be affected.

Questions:

1. Are diodes light resistors? In what way?

          I believe that diodes are considered as light resistors because they act as resistors also and they produce light when voltage is applied.

2. What are some practical applications of diodes?

          Some applications of diodes are in digital clock and traffic lights.



Conclusion:

         LED is really a light resistor in the sense that it has resistance but can produce light. In general, diodes have polarity in which it must be considered and followed in connecting it to a circuit.

References:

Retrieved on Sepptember 3, 2015 from http://whatis.techtarget.com/definition/diode

Retrieved on Sepptember 3, 2015 from http://www.instructables.com/id/Types-of-Diodes/

Retrieved on Sepptember 3, 2015 from http://www.technologystudent.com/elec1/diode1.htm