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