Once zero crossing points are determined, triac-based electronic circuitry can be exploited to cut off the pulsating DC voltage at any point in its cycle, allowing only of the portion of the power to get through to the lamp. If the AC voltage is converted to pulsating DC via full-wave rectification, the transition points remain the same, and the electricity can be used to power a resistive load, such as an incandescent light bulb. Modified image source: Lewis Loflin's video: More from Lewis at Below, the spikes indicate where the zero crossing occurs. Looking at the top portion of the picture, notice that the wave periodically crosses the zero axis. The diagram below illustrates two complete AC voltage cycles. To understand how it does its job, we need first to observe the types of waveforms that need to be generated. Triac ELV dimming is a method used to vary the brightness of an incandescent bulb. Once the voltage passing through the output get close to zero, it takes another input pulse to once again allow the flow to resume. Once turned on by either a positive or negative pulse at its input, the triac allows electricity to flow unimpeded through its two outputs. It can be thought of as a triode AC switch. So, lets first examine this crucial semiconductor, and how this solid-state switching device serves to affect intensity control for both incandescent and LED lights.Ī triode for alternating current, or triac, is a power semiconductor device, a bidirectional device similar to a thyristor. The key to any kind of light dimming is the triac. Best of all, they are compatible with the ubiquitous TRIAC/ELV/SCR phase dimmer and will work with most traditional dimmers in the market.
Fortunately GRE Alpha's XLA series of electronic low voltage dimmers makes that simple. LEDs are best controlled by keeping their voltage constant and varying current, or vice versa. The upshot of this fact is that they don't respond in a simple, linear manner to changes of inputs. LEDs, on the other hand, are, after all, semiconductors. They can be controlled by a method well known as phase cut. For lightbulbs, the issue is relatively simple, because these old standbys are purely resistive devices.
One tough issue for LEDs is how to control their intensity. Why Controlling LED lights is More Complex than it was for Old-style Incandescents Under the right circumstances, they can last almost indefinitely. Light emitting diodes, or LEDs, can be configured to glow in a variety of colors, and emit far more light per watt as compared to incandescent.
Slowly but surely, incandescent lightbulbs are being confined to history, along with the vacuum tube, the telegraph, and soon enough, the internal combustion engine. Then came the age of semiconductors, and it was soon discovered that under the right circumstances, semiconductor diodes can be configured to emit light. Life no longer needs to slow to a standstill at sunset, and we now live in a 24x7 world. Incandescent lighting has been around for over a century now, and it has served to completely change the human experience.
Any help would be greatly appreciated.Back to index GRE Alpha makes it easy to achieve flicker free control for all your LED lights – without ditching your existing infrastructure I can't find a pattern other than the ELV+ dimmers. This happens for under-cabinet LED strips, recessed LED wafer lights, traditional dimmable fixtures (chandeliers, pendants, ceiling mounts), etc. This seems to happen only for lights on the ELV+ dimmers, the lights on on/off switches do not do this. It is a large house, so I have 60 caseta devices on my hub. I am using the Caseta Hub with a simple evening schedule but this happens regardless of the schedule, whenever and however the lights are turned on. This house is a new construction, so all new wiring. Not to mention that it scares my daughter and my dog who think the house is haunted -)Īny thoughts on what might be causing this? It is not flickering, just turning off and back on, as if performing some sort of reset.
It is not that big of a deal but it is annoying when having dinner and what not to have the room go full dark and then back to light.
This seems to happen when the lights are on for more than 30 minutes or so. This happens regardless of whether the lights are at 100% brightness or 10% brightness. However, when I turn on lights with dimmers (all my dimmers are ELV+), whatever lights are turned on will "cycle" off and on from time to time. I love the caseta wireless system overall.