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.	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 Emitter Ultra-Violet used in money watermark detectors, blood and stain detectors #324 20 Pak / $3.80	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 Focused light output Resistor needed at 4.5 volts #552 9 Pak / $2.79	12000 mcd LED 5mm White Emitter View Angle 15 Degrees #136 35 Pak / $16.80
1000 - 1500 mcd LED 5mm Yellow Emitter Input voltage:1.9V-2.0V #744 10 Pak / $1.50	1000 - 1500 mcd LED 5mm Red Emitter Input voltage:1.9V-2.0V #745 10 Pak / $1.50	8000 + mcd LED 5mm Green Emitter (515~520nm wave) Input voltage: 3.2V~3.4V #743 10 Pak / $1.80	1500-2000 mcd LED 5mm Blue Emitter #144 10 Pak / $1.60