established 1992 Electronics - Parts & Accessories
Online Shopping

Tel: 604-984-7322        mail@cordsplus.com
Light emitting diodes (LED's) are electronic components that produce light without heat or high voltages. When using LED's in a DC circuit there are some basic rules you will need to follow.  LED's must be operated in such a way that the current through the LED is kept within the limitations of the device. The simplest is to place a current limiting resistor in series with the LED. The resistor value can be calculated using Ohm's law.  Each LED type has specification called "forward voltage drop", they also have a specified current limit. Both these specifications are required in order to calculate the size of the resistor required to limit the current. The following is a general guideline for LED's without specifications.





Single LED
Forward Voltage Drop:


Regular red 2.0v
High brightness red 2.2v
Super bright red 3.0v
Orange or yellow 2.0v
Regular green 2.0v
High Brightness green 2.2v
Super bright green 3.3v
Blue 3.4-4v
White 3.4-4v


Forward Current

20mA is a common standard
value for most LED's.


Anode & Cathode

Most Led's have a long lead and
 a short lead, the longer lead is the anode ( positive ) and the shorter
 lead is the cathode ( negative )
Calculating the Value of the Current Limiting Resistor

Using a standard green LED with 2.0
Volt forward voltage drop and a forward
current of
20mA and we want it to
run in a
12 Volt DC circuit.
( 20mA = .02 Amps )

Using Ohm's law:
Subtract the forward voltage drop
from the supply voltage.
12 Volts - 2 Volts = 10 Volts

Then:

10 Volts Divided By .02 Amps
= 500 ohms


As resistors come in standard values,
choose the next highest value, this will
reduce the current slightly.

To calculate the wattage rating of the
required resistor:

W=A x V    .02 x 10=.2 watts    Therefore use a 1/4 watt resistor

Connecting Multiple LED's in Series

Series LED's are connected cathode
 to anode to cathode to anode. The
 limiting resistor is placed between
 the voltage source and one of the
LED leads. In this type of circuit
you need enough voltage to power
 the number of LED's you are using.
 
To calculate the required resistor:
Add the forward voltage drop for each
 LED together and subtract the total
 from the supply voltage.

For example if you have 4 LED's each
 with a 2 Volt voltage drop and a
supply voltage of 12 Volts DC:
4 x 2.0V=8.0V    12V-8.0V=4.0V
  4.0V will be the voltage at the resistor.

Then:

4.0V divided by .02A=200 Ohms
 use the next highest standard
 resistor value


For the resistor wattage: .02A x
 4.0V=.80W ( 1/4 watt resistor ).

With a series LED circuit you can use
 any combination of LED colors with
 different voltage drops.
Serial LED

Parallel LED

Multiple LED's in Parallel


LED's in parallel is not a good idea.
 The LED's will not have exactly the
 same voltage drop and because of
 these differences they will have
 different brightness levels and may
 be destroyed by the larger current
 flowing through it.



5mm Ultra-Violet Emitters
5mm Ultra-Violet Emitter

Ultra-Violet used in money watermark detectors, blood and stain detectors

#324 
20 Pak / $3.80
5mm IR LED Emitters
5mm IR LED Emitter

IR illumination for night vision
equipment and
 applications

 Input voltage:
1.7Volts - 2.2 Volts


#145 
20 Pak / $3.80
10.5mm LED Emitter
10.5mm LED Emitter

Focused light output
Resistor needed
at 4.5 volts

#552  
9 Pak / $2.79
1200 mcd 5mm White LED Emitter
12000 mcd LED 5mm
 White Emitter View
Angle 15 Degrees


#136  35 Pak / $16.80
5mm Yellow LED
Yellow LED

1000 - 1500 mcd  LED
 5mm Yellow Emitter
 Input voltage:1.9V-2.0V

#744  
10 Pak / $1.50
5mm Red LED
Red LED

1000 - 1500 mcd LED
 5mm Red Emitter
 Input voltage:1.9V-2.0V

#745 
10 Pak / $1.50
5mm Green LED
Green LED

8000 + mcd LED 
 5mm Green Emitter
 (515~520nm wave)
Input voltage: 3.2V~3.4V
#743 
10 Pak / $1.80
Blue LED Emitter
5mm Blue LED


1500-2000 mcd LED

5mm  Blue Emitter

#144 
10 Pak / $1.60


1400 mcd 5mm White LED Emitter

14000 mcd  LED Emitter

 5mm White
 
14000 mcd LED


# 719  5 Pak / $1.15



8 Volts 250 ma Type A lamp


8 Volts 250 ma
 Type A Lamp


#82 
7 Pak / $10.08


Mini Traffic Light Kit



Assembled mini traffic light kit. It has 3 LEDs: one green, one red and one yellow. After connecting the power, it takes a few seconds before the LEDs start flashing sequentially, one after the other. It is possible to connect up to 12 LEDs to the circuit using 4 of each colour. The additional LEDs are not included. Specifications: Supply Voltage: 4.5 - 6Vdc Supply Current (using 3 LEDs): 350mA at 6V Dimensions: 35 x 45mm, 25mm heigh
t

#10008  $9.50


"Blinder" LED Flasher Kit
"Blinder" LED Flasher Kit

Kit features 3 crystal clear special
 LEDs  which create brilliant flashes of
 orange-red light. The light output of
this flasher kit can be seen in direct
 sunlight.  Great for night joggers,
 bicyclists, warning markers, etc.
 Size of PC board: 2" x 1.4".
 Operates on one 9V battery
 (not included).
 Flash rate is adjustable with the built-in trimmer potentiometer. Complete with all parts, PC board
 and instructions. Skill Level 1. This
 kit requires soldering of components
 to the PC board while building.


#820  $8.07






LED Tester
LED Emitter Tester

#716 $8.00


Bulk LED

Bulk LED Emitters

One big mess of prime new LEDs.
No specifications are available.
100 pieces of  LED emitters, some in plastic housing, and some IR Emitters.
Apply 1 volt dc and step up till you get
 a glow from the lamp to find the
 forward voltage.

#521 
100 Pak / $6.00

Main Product Page

Home Page

Site Map

Contact Us

Ordering Product
 
All Prices in Canadian Currency
Currency Converter
Custom Search
Solution Graphics



Pricing and availability can change after being posted on site - please contact us for current prices