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Glow Led Event Details: Overview

1. The document provides details for an LED lighting event called TECHNOFEST 2016, which will involve participants creating a world map and other designs using LEDs, resistors, and breadboards. 2. The event rules specify that teams will have 1 hour, 200 Pakistani rupees per team, and supplies of LEDs, resistors, and breadboards to complete their designs. Points will be awarded based on correct use of LEDs and the creativity, neatness, and teamwork of the designs. 3. Guidelines are provided on choosing resistor and LED voltages that will work effectively with different power supply voltages. Tips are also given on connecting LEDs in series and parallel circuits.

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Aurangzaib Jahangir
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63 views4 pages

Glow Led Event Details: Overview

1. The document provides details for an LED lighting event called TECHNOFEST 2016, which will involve participants creating a world map and other designs using LEDs, resistors, and breadboards. 2. The event rules specify that teams will have 1 hour, 200 Pakistani rupees per team, and supplies of LEDs, resistors, and breadboards to complete their designs. Points will be awarded based on correct use of LEDs and the creativity, neatness, and teamwork of the designs. 3. Guidelines are provided on choosing resistor and LED voltages that will work effectively with different power supply voltages. Tips are also given on connecting LEDs in series and parallel circuits.

Uploaded by

Aurangzaib Jahangir
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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GLOW LED

EVENT DETAILS
For TECHNOFEST 2016

OVERVIEW-PROVISIONAL APRIL 2016


LEDs, Resistors and Breadboards will be used to form a WORLD MAP. The structure will be an image of different
colors for continents and oceans. The second part will be No-Boundaries Section. In this, teams will be free to make
anything of their own choice or on a particular topic assigned to the teams on sight. The rules are:

1. TWO MEMBERES PER TEAM


2. 200PKR PER TEAM
3. SUPPLIES: Resistors , Breadboards , LEDS (R,B,G,W (Other colors will be added))
4. 1 hour to complete
5. No Borrowing / lending / exchanging / for burned up LEDs.
6. Points to be given on the basis of LEDs used correctly.
7. Points for Neatness, Creativity, Teamwork.
8. Presentation/Viva points.
9. After ruling, the top three best structures would be awarded.

1
GUIDELINES:

Some good values to try:

As supply voltage:
For molex: 5, 7 and 12 volts
Batteries: 1.5 and 9 volts

As led forward voltages:


Red and green: 2 volts
Blue and white: 3.0 - 3.5 volts

Led current:
20mA will work for most regular leds.
Super bright leds can go from 30mA up to several amps.

VISIT: http://ledcalc.com/ for CIRCUITS

CONNECTING A LED
A LED must be connected around the correct way in a circuit and it must have a resistor to limit the
current.
The LED in the first diagram does not illuminate because a red LED requires 1.7v and the cell only
supplies 1.5v. The LED in the second diagram is damaged because it requires 1.7v and the two cells
supply 3v. A resistor is needed to limit the current to about 25mA and also the voltage to 1.7v, as
shown in the third diagram. The fourth diagram is the circuit for layout #3 showing the symbol for the
LED, resistor and battery and how the three are connected. The LED in the fifth diagram does not work
because it is around the wrong way.

2
A standard 9V battery has about 400-600 mAh capacity. In the most basic terms, these batteries can supply about
500 milliamps for one hour before being "dead".

LEDs IN SERIES
LEDs can be placed in series providing some features are taken into account. The main item to include is a current-
limiting resistor.
A LED and resistor is called a string. A string can have 1, 2, 3 or more LEDs.
Three things must be observed:
1. MAXIMUM CURRENT through each string = 25mA.
2. The CHARACTERISTIC VOLTAGE-DROP must be known so the correct number of LEDs are used in any string.
3. A DROPPER RESISTOR must be included for each string.
The following diagrams show examples of 1-string, 2-strings and 3-strings:

to Index

LEDS ON 12v
When connecting LEDs to cars and trucks, you have to allow for an increase in voltage
during the time when the battery is being charged. Normally the battery sits at 12.6v,
but when charging, it can rise to 13.5v or slightly higher.
If you put 3 white LEDs in series, the "head" voltage will be about 1.8v when the battery
is 12.6v, but increase to 2.7v when it is charging.
This will increase the current through the LEDs by about 50% and will be noticeable as
the brightness will increase considerably. The extra current may also damage the
LEDs.
To keep an even brightness, we suggest using strings of LEDs with just two white
LEDs and 220R 0.25watt resistors as shown in the following diagram.
Red, green, orange, yellow and blue LEDs have a different characteristic voltage
across them when illuminated and so you can have more LEDs in a single string, with a
suitable current-limiting resistor.
Here is the answer for each colour:

3
25mA is the MAXIMUM for 3mm and 5mm ordinary, high-bright or Super-bright LEDs.

http://www.talkingelectronics.com/projects/30%20LED%20Projects/30%20LED%20Projects.html

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