LEDs Buying Guide

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LEDs Buying Guide

LED stands for light emitting diode, which is a semiconductor light source used as indicator lamps in numerous appliances and gadgets, as well as for illumination. When LEDs were introduced in the early 1960s, they only emitted low intensity red lights. However, contemporary LEDs have multiple wavelengths, including ultraviolet, infrared, and visible wavelengths with ultra-brightness. When LEDs are switched on, the electrons within the device is once again able to reconnect with their respective receptacles, which releases photon energy. The result is referred to as electroluminescence, and the light colour which corresponds to the photon energy is determined by the semiconductor's energy gap.

LEDs are generally small, measuring less than a millimetre, and their radiation pattern can be shaped using integrated optical components. The good thing about LED lights is that they consume less energy than incandescent light sources, and they also have a longer lifespan. Aside from the main purpose of lighting, LEDs are also popular in LCD TVs. Before buyers attempt to purchase items that utilize LEDs, they should first learn a bit more about the different LED types and colouring, the types of lighting and equipment that they are used in, and the different ways they can be used.

LED Colours

Buyers may see LEDs in various sizes and shapes, where the colour of the lens plastic is often a similar colour to the LED colour. Luminous efficacy, measures how well visible light can be produced by a particular light source. The highest efficacy is 100. The chart below highlights the wavelength and efficacy for each major LED colour.

Colour

Range of Wavelength

Typical Efficacy

Red LED

620 < λ < 645

72

Green LED

520 < λ < 550

93

Blue LED

460 < λ < 490

37

Yellow /Cyan LED

490 < λ < 520

75

Red-Orange LED

610 < λ < 620

98

Initially, LEDs started out with infrared devices that were made with gallium arsenide. However, with the advancement in technology and material science, devices are now being made with shorter wavelengths, which emit lights in various different colours.

Types of LED

There are three main types of LEDs: miniature LEDs, mid-range, and high power LEDs. They can sometimes be found in custom designs, including multi-colour or alphanumeric types.

Miniature

Miniature LEDs mostly refer to single-die types that are often used as indicators. They can be found in various sizes ranging from 2 to 8 millimetres in surface mount and through-hole packages. These miniature LEDs do not generally have a separate heat sink, and their distinctive ratings range from approximately 1 to 20 mA and beyond. There is a max boundary on power consumption because of their small size and due to heat from the high current density.

Miniature LED Shape

The miniature packages are often round with a flat top or a domed top, but there are also triangular shaped packages with a flat or square top and rectangular shaped packages with flat tops. Sometimes, the capsule that covers them can be clear or have a tint to increase the viewing angle and colour contrast

Three Types of Miniature LEDs

Miniature single die LEDs have three sub categories: low current, standard, and ultra-high output. Low current ones are generally rated at 2 mA with approximately 2 V, which may calculate to a 4 mW consumption. Standard LEDs are 20 mA at 2V, which approximates to 100 mW consumption for white, blue, and violet LEDs. The ultra-high output LEDs are also 20 mA but at either 2, 4, or 5V. These LEDs with high voltages are used for direct sunlight viewing. For instance, 5 and 12 V LEDs are actually regular mini-LEDs that have been designed to facilitate an appropriate series resistor for the purpose of direct connection with a 5 and 12 V power supply, respectively.

Mid-Range

Mid-range LEDs are also referred to as medium-powered LEDs, which are generally through-hole mounted. They often use only a few lumen output quantity as needed, and the diode is sometimes mounted to two cathode leads and two anode leads to facilitate better heat conduction. Some of these LEDs are often used in light panels, tail lights on motor vehicles, and emergency lights. They are able to better handle high currents due to their higher amounts of metal. They sometimes accommodate currents up to 100 mA, and such a current enables a higher light output, which is often needed for the emergency lights and vehicular tail lights.

High-Power

High-power LEDs are also called HPLED and they may be driven by currents ranging from 100s of mA to over an ampere. This is extreme when compared to other LEDs that only use mAs in the 10s region. Some of these HPLEDs can produce more than 1,000 lumens. If these high-powered LEDs become overheated, they may be destroyed, so they have to be mounted on a dedicated heat sink in order to dissipate heat. Without the heat sink to remove the excess heat, the LED device may fail in just a few seconds.

Uses of High-Power LEDs

Oftentimes, it takes just one HPLED to supplant a regular incandescent bulb in a flashlight. It can also be used in a group to create a very powerful LED lamp. There are some HPLEDs now that exceed 105 lm/W, which are installed in lamps that are used in place of incandescent, fluorescent, and halogen light.

AC or DC Powered

Some LEDs are also made to operate on AC power without needing DC conversion. For every semi-cycle, the LED is dark on one side while the other side emits light, and then it reverts during the other half of the cycle. This type of HPLED often carries an efficacy value of 40 lm/W. In recent years, manufacturers have created LEDs with high DC voltage that uses a simple controlling circuit to drive the LED from AC power. These LEDs have low dissipation, which makes them more flexible when compared to regular AC LEDs.

LED Variations Based on Application

LEDs are used in various situations. The type of LED and the LED colour vary greatly depending on its current purpose. The casing also has diverse emitters to facilitate the LED application.

Flashing LEDs

These LEDs are generally used to grab attention without the need for additional electrical components. Flashing LEDs look the same as standard LEDs, but they are built with an integrated multivibrator circuit, which is responsible for the flashing per second. Oftentimes, the flashing LEDs are made to only emit one light colour, but evolving technology has led to flashing LEDs with multiple colours that can even fade through colour sequences via RGB colour mixing.

Bi-Colour LEDs

As the name implies, bi-colour LEDs have two emitters in the same case. They can also be subdivided into two parts, where one type has two dies that are connected to two leads, but they are not parallel. The current emits one colour when flowing in a particular direction and emits another colour when flowing in the other direction. The other type also has two dies with their own leads and another lead that is used with the cathode or anode in order to have separate controls for each.

Tri-Colour LEDs

Similar to the bi-colour LEDs, the name indicates the number of emitters that can be found in one case. The individual emitters are connected to individual leads in order to facilitate independent control. Four lead types would pretty much have one anode or cathode lead in addition to individual leads for each colour.

How to Buy LEDs on eBay

There are many types of LED lights on eBay, so buyers can easily find what they are looking for. The first step is to perform a search for LEDs from the eBay homepage and look through the variety available on the results pages. These results can then be filtered down to specific types of lights, LED colour, brands, and even the room that they are recommended for. This general search is especially good when you need to buy a variety of LED types for different reasons.

If you are sure of a specific LED type, colour, brand, or any other characteristic, you can input some of those details into your homepage search, and that should eliminate multiple items that may not be of interest. Therefore, you spend less time browsing through unrelated items and more time making a quick selection. For instance, you can quickly search for "blue bedroom LED lights" to eliminate other colours and room types. The same can be done for brand and style such as "Premier Christmas LED lights", which would narrow down the brands and the occasions. After searching and filtering, you should contact the sellers to confirm the details, including shipping and payment options.

Conclusion

Due to the wide variety of LED styles, types, and colours, buying LEDs can sometimes be a daunting task, especially if buyers are unsure of the types they need. Different persons may require LED lights for different reasons, so they should always try to find out which LEDs are more conducive to the purpose that they are intended for. Buyers may need to learn more about the various LED colours as well as the different types of LED and their sizes and power requirements before making a purchase. Additionally, some LEDs are better used in some applications than others, so buyers need to become familiar with the LED application breakdown.

Once these factors have been taken into consideration, buyers simply need to find a store that houses a wide variety of LEDs to avoid a long and frustrating shopping experience. Luckily, eBay provides multiple LED options for shoppers to choose from and also makes the shopping experience even more pleasant by providing a strong internal search engine with relevant product filters.

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