Trailing or Leading edge LED dimming

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Dimmable retrofit LED lamps and LED-based luminaires has long been recognized as an issue when it comes to the attenuation methods such as trailing and leading edge. However, there is not often problems when it comes to the DALI and 1-10V. Rune S. Larsen, the founder of the company Normasym, describes the two ways to dim the LED lights when there is attenuation of the main voltage.

The quick drop in prices of LED retrofit lamps has ensured a massive increase in the purchase of such light sources. The quality, as well as the selection of lamps, has increased over the past years. However, there are still a few challenges. Light dimming of such light sources is not always easy.
It can be difficult to know if a new LED retrofit lamp can be installed instead of an old incandescent lamp and still function with the old dimmer. Therefore, it is important to know the specifications of both the LED light source and the dimmer.
Dimming of the light is usually an important feature in the living room, and many people do also enjoy to have the opportunity of dimming the light in the bathroom. Additionally, dimming the LED light often extend the life of the light source significantly.

Trailing edge - electronic dimmer

The trailing edge dimmer came out after the leading edge dimmer, but after the halogen bulb was introduced on the market, the trailing edge dimmer has been the most popular one.
The trailing edge dimmer is a dimmer switch which can handle electronic components. It has numerous functions and can dim low voltage halogen lamps with electronic ballasts, LED retrofit lamps and lights, energy saving light bulbs and other light sources with an electronic ballast.
The trailing edge dimmer is designed for a capacitive load and is not a perfect match with high currents, but it will dim the lights without any annoying sounds.

Leading edge - triac dimmer

The leading edge is traditionally used with incandescent lamps and iron core transformers in connection with the dimming of halogen lamps. Leading edge creates a quick, stable voltage on the circuit. This also stabilizes the current in the circuit directly to the light source.
The leading edge dimmer is not as silent as the trailing edge dimmer, depending in particular on the quality of the dimmer and whether it is loaded above the prescribed minimum load.

The best dimmer for LED lighting

When wanting to find the perfect dimmer for LED lighting, one has to look at the specifications of both the light source and driver (transformer) as well as the dimmer.
Trailing edge, however, is the most popular dimmer with LED light sources, but as many LED lamps are designed for use in existing installations, manufacturers often meet the market with LED lamps that handle a leading edge dimmer.
So the short answer, when it comes to finding the perfect dimmer for LED retrofit lamps, is; most LED lamps can be dimmed with both solutions, but the trailing edge dimmer will be capable of handling more stable dimming of the LED product versus the leading edge dimmer.

Credit for picture used in this article: Busch Jaeger