Frequently Asked Questions What is an LED? Light-emitting diodes, or LEDs, have been around for more than 30 years, but until recently were used only in small electronic devices as indicator lamps. Light Emitting Diodes, as the name states are diodes. A diode is a semiconductor device. Semiconductor diodes have a junction separated by two materials one material has a surplus of positive charge electrons, and the other a surplus of negative charge electrons. When you apply a forward voltage, electrons are brought together. They combine near the junction, and this releases light energy. What is the useful life of LEDs? The number 100,000 hours (about 11 years) gets mentioned a lot. However incorrect manufacturing processes can reduce this to as little as 100 hours, unlike when you buy a packet of light bulbs, you see a number on the box that says something like life: 1125 hours.?This is defined as the time it takes for 50% of test samples to burn out. But there no standard definition like this for LEDs, they gradually decrease in brightness instead of immediate failure such as the globe and inferior quality manufacturers attempting to gain a high brightness will alter the LED lifespan, so it becomes more useful to mention umen maintenance? LED manufacturers publish a curve of light output vs. time, which describes the LED lumen maintenance profile. So lumen maintenance is the most important specification for a designer building arrays of LEDs for illumination. By manufacturing within the boundaries of output vs. time, we can manufacture our circuit board so as to maximize the lifespan of our LEDs. The electrical characteristics of LEDs? A typical LED has a forward voltage rating between 2 and 4 Volts. The red, yellow, and orange types have a forward voltage around 2 Volts, while the blue, white, and true green types have a forward voltage around 3.3 Volts. The typical drive current for LEDs is 20 milliamperes (mA). From this you can see an LED uses a modest amount of power, a few tens of milliwatts compared to the few tens of Watts an incandescent bulb uses. In other words, the power used by an LED is one thousandth of that used by a familiar light bulb. Since an LED is a diode, even after it ceases to produce light, it will still use power, and if connected with other LED in series should allow the others to continue working. Why white LEDs cost more ? The manufacturing process to create white is to combine red, green, and blue coloured Phosphor. When you get the right mix, the effect is white light. This is the same way your television works, the white object on the screen is really depicted using dots of red, green and blue lit up in proportions that form an impression of white, hence the cost of the white LED is governed by this expensive manufacturing process. Our white LEDs are photo-metrically tested to comply within the correct chromaticity boundaries for the Australian Design Rules. Some whites depicting a blueish (Cool White) or yellowish (Warm White) tinge are the product of the outer edges of the pure white material and are sold off for torch lights and decorative lights, however inferior quality manufacturers will try to use these for automotive lighting because they are less expensive.