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