characteristic of an led

7/27/2019 Characteristic of an LED

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Characteristic of an LED

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Table of ContentsTABLE OF FIGURES ..................................................................................... 1INTRODUCTION ......................................................................................... 3

Diode ......................................................................................................... 3

LED ............................................................................................................. 3

COM3LAB ................................................................................................... 4

PROCEDURE ............................................................................................... 51. Startting the experiment ....................................................................... 5

2. Circuit Connection. ............................................................................... 5

3. Instrument Settings. ............................................................................. 8

A. Function Generator ............................................................................. 8

B. Oscilloscope ....................................................................................... 9

CONCLUSION ........................................................................................... 10

TABLE OF FIGURES

Figure 1, LED CIRCUIT SYMBOL ......................................................................................... 4

Figure 2, com3lab kit ....................................................................................................... 4

Figure 3, leds with different colors and one digital led screen .......................................... 5

Figure 4, Red line the between G1 and h1 ........................................................................ 6

Figure 5, Y1 connection .................................................................................................... 7

Figure 6, Y2 connection .................................................................................................... 8

Figure 7, Function Generator settings ............................................................................... 9


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Figure 8, Oscilloscope ...................................................................................................... 9

Figure 9, Oscilloscope Settings ....................................................................................... 10

Figure 10, Characteristics of red and green leds ............................................................. 11


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L I G H T E M I T T I N G D I O D E C H A R A C T E R I S T I C S , R E P O R T O N T H E

T H I R D E X P E R I M E N T O N E E 3 1 3 1

INTRODUCTION

Before we start the experiment, we must discuss the concept of diodes and LEDs. Also we

have to introduce the technology used in our experiment.

DiodeThe diode is a device formed from a junction of n-type and p-type semiconductor

material. The

lead connected to the p-type material is called the anode and the lead connected to the

n-type

material is the cathode. In general, the cathode of a diode is marked by a solid line on the

diode (1)

LEDLight Emitting Diode converts current to light. When a forward-bias voltage is applied

across a pn junction,

electrons and holes flow across the space-charge region and become excess minority

carriers. These excess

minority carriers diffuse into the neutral semiconductor regions, where they recombine

with majority carriers. (2)


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FIGURE 1, LED CIRCUIT SYMBOL

COM3LABCOM3LAB Multimedia is a learning system to help provide training for electronic and

electro-technical qualifications. For a better understanding, the COM3LAB multimedia

courses treat the electro-technical items graphically and clear. (1)

FIGURE 2, COM3LAB KIT


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PROCEDURE

1.Startting the experimentAfter connecting the kit USB cable to the PC, start the software and select experiment

no. 3. As seen in figure 2, press next.

FIGURE 3, LEDS WITH DIFFERENT COLORS AND ONE DIGITAL LED SCREEN

2.Circuit Connection.i. First we connect the red LED with the function generator and later - after

graphing the red characteristics - we connect the green and repeat the steps.

H1: Red LED.

H2: Green LED.

G1: Function Generator.


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FIGURE 4, RED LINE THE BETWEEN G1 AND H1

ii. As shown on figure 5, we connect the Y1 channel of the oscilloscope in parallelwith H1.


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FIGURE 5, Y1 CONNECTION

iii. After that, we connect Y2 channel in parallel with R1 resistor as shown below onfigure 6.


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FIGURE 6, Y2 CONNECTION

3.Instrument Settings.A. Function Generator

We set the wave form triangular with peak voltage Vpp = 20v and frequency

of 50Hz.


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FIGURE 7, FUNCTION GENERATOR SETTINGS

B. OscilloscopeAfter we open the oscilloscope and its control panel,

- Set Mode to X/Y.- Y1 Volts/div = 1v or 2v.- Y2 Volts/div = 1v or 2v.- Y2 Variable = -1 (By pressing the button inv.)- Time/div = 2ms.

FIGURE 8, OSCILLOSCOPE


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FIGURE 9, OSCILLOSCOPE SETTINGS

CONCLUSION

The characteristic of the LED is similar to that of a silicon diode, although its threshold

voltage is notably higher. The threshold voltage of an LED is termed gate voltage. This

voltage depends on the energy of the emitted light. The threshold voltage of an led is

also termed gate voltage. It is higher than the threshold voltage of a silicon diode. Light is

mitted on attainment of this threshold. The value of the gate voltage depends on the

color of the light


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FIGURE 10, CHARACTERISTICS OF RED AND GREEN LEDS


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characteristic of an led

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