Diodes

Caupayan, Jedda Anne G.

Diodes

Since we are done talking about resistors, capacitors and potentiometer, let us move on to one of the most essential device in the field of electronics.

Definition:

Diode is one of the electronic devices that is composed of semiconductors like germanium and silicon. It is also a two passive terminal device, the anode and the cathode, by that it concerns of the polarity in connecting in the voltage source. It would also allow current to move through in one direction with far greater ease than the other.  Diode also controls the direction of current flow. The current that will pass through the diode will have only one direction. If the anode is connected to the positive terminal and the cathode in the negative terminal, the current will flow from the anode and that is called the forward biased and if the anode is connected to the negative terminal and the cathode is connected to the positive terminal, the current will flow from the cathode and it is called reversed biased. We will tackle about that later in this topic.

Types of Diodes

1.  Light emitting diode - another type of diode is the  light emitting diode or LED is one of the most popular types of diode. When forward biased with current flowing through the junction, light is produced. The diodes use component semiconductors, and can produce a variety of colours, although the original colour was red. 

Retrieved from: https://goo.gl/SF58xv

2. Photodiode - another type of diode is the the photo-diode. It is used for detecting light and it can be found when light strikes a PN junction that is why it can create electrons and holes. Photo-diodes can also be used to generate electricity.

 Retrieved on September 3, 2015

 From https://goo.gl/QsfH6J

3. Schottky diode - it is another type of diode that has a lower forward voltage drop than ordinary silicon PN junction diodes.To achieve this performance they are constructed in a different way to normal diodes having a metal to semiconductor contact. They can be widely used as clamping. 

Retrieved on September 3, 2015

 From https://goo.gl/sHWPx2

4. Varactor diode - it is another type of diode that is used in a lot of radio frequency applications.

Retrieved on September 3, 2015

 From https://goo.gl/QtRWZW 

5. Zener diode - it is another type of diode that is a very useful type of diode because it provides a very stable reference voltage. It is run under reverse bias conditions and it is found that when a certain voltage is reached it breaks down. If the current is limited through a resistor, it enables a stable voltage to be produced. This type of diode is therefore widely used to provide a reference voltage in power supplies. 

Retrieved on August 30, 2015

 from http://goo.gl/AaVmIS

DIODE ACTIVITY

I.                    Objectives:

At the end of the lesson, the students will be able to:

a.       determine the voltage and current flow of LED in a circuit;

b.      differentiate the voltage of LED between the two types of circuit.

II.                  Materials:

Voltage regulator                         Multitester                                             breadboard

LED               Connecting Wires

III.                Procedure:

1.       Connect the five LED in series connection.

2.       Applying a certain voltage output, determine the voltage drop and current on each LED.

3.       Repeat the procedure with increasing voltage output.

4.       Perform 5 trials.

5.       Do the same procedure but now, the five LEDs are connected in parallel connection.

6.       Record the data on the table.

V. Data and Result:

Table 1: LED in Series Connection

Vout	Voltage Drop, V					Current, I
	V1	V2	V3	V4	V5	I1	I2	I3	I4	I5
8.0V	0.4V	0.4V	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	40mA	40mA	40mA	40mA	40mA
16.0V	3.8V	2.8V	2.6V	3.2V	3.0V	145mA	145mA	145mA	145mA	145mA

Table 2: LED in 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.

Based on the data gathered, it was observed that the light emitted by the LEDs in parallel connection were brighter with the voltage drops that are greater in value compared to the series connection.

IV.                Questions:

1.       How does the light emitted differ between the two circuits?

Answer: The LEDs in the parallel connection were brighter than the LEDs that were connected in series.

2.       What is the difference on the voltage drop between series and parallel?

Answer: It was very evident that the voltage drop in parallel was greater in value than the voltage drop in series connection

V.                  GENERALIZATION:

Based on the experiment we determined the difference of the brightness of light emitted by the LED which depends on the type of the circuit connection.

Retrieved from: https://learn.sparkfun.com/tutorials/diodes

Retrieved from: http://whatis.techtarget.com/definition/diode