LEDs function like a normal diode: It works like a check valve and will allow the current to pass through in only one direction. Therefore, the LED must be operated and connected in the open direction in order to get the LED to emit light. This is achieved by connecting the anode with the positive pole and the cathode with the negative pole. If this is connected in reverse, the current will not flow through and the LED will not light up. If the LED is accidently connected to an AC (alternating current) the so called 60Hz - Flicker will occur. This is the result of the of the positive and negative changes of the half wave (cycle) Depending upon the color of the LED, the operating voltage can vary from 1.8V to 3.6V.

A standard 5mm LED, operates an a maximum current of 20mA. A higher current will cause over-heating and reduce life expectancy significantly or may also destroy the LED immediately. Therefore, LEDs should only be operated with and inline resistor, sized according to the supplyed voltage.High power LEDs demand a strickter operating standard for a uniform control of current.Only by using precise current (example: 350mA on 1W LED or 700mA on a 3W LED) the maximum brightness will be achieved, without destroying the LED. The high power LEDs should only be operated with a special LED driver.

Standard electronic components have a tolerance of up to 10%. The LED driver delivers a very precise and controlled current , even when the voltage fluctuates. Voltage fluctations in a normal power supply will also result in a fluctuation that may exceed the maximum allowed current of the High Power LED causing premature failures. When a white High Power LED is connected to a 350mA constant current driver, secondary voltage is approximately 3.2V.

High Power LEDs require a very specific and uniform control of current. High power LEDs give too great or too little current will result in a low light output or destroy the LED. LED drivers deliver a precise controlled current, even when the current fluctuates.

EXAMPLE: a 1W - 350mA high power LED requiring 3.2V is connected to a 350mA driver. If another LED is connected (in a series as specified) the driver automatically increases the voltage to 6.4V with a constant 350mA current. Optimal conditions to get the most light and life from you LED regardless of current fluctuations and the need to increase LEDs.

The diagram below shows the basic neccesities to operate a high power LED.

1. a transformer to step down US standard 120 volts to 12, 24 etc.

2. a bridge rectifier to convert AC to DC (all LEDs require a DC current)

3. a constant current regulator to control the amperes to the LED.

LEDs require all three components to run, one could have any of the three separate components included and sometimes none.

(The LED driver is all 3 items in one, and your smartest high power LED power source)