Seen this in many houses, people upgrade their lighting setup and install a dimmer. Which works. But usually it also makes the lights flicker unintentionally, which is super annoying IMO.
Now, my understanding of electrical engineering is pretty rudimentary so I’d appreciate more something that explains the concept in a way that Cavewoman Mothra can understand rather than something technically accurate.
Thanks
Power coming into the house is AC which means 50-60 times a second the power goes from +110/240V to -110/240v.
LED lights run off DC power, so to change the power type a capacitor is somewhere that holds enough charge to keep the item working until the AC power is back to a usable positive value.
Dimmers limit the power going to the light, so the capacitor doesn’t charge enough to keep the light and circuitry on for the full negative swing of AC power.
This is ungodly rudimentary, and corrections are welcome. There is also many nuances I am missing.
Thanks, some of this makes sense. But why is it then not constantly flickering? They usually flicker for, say, five seconds then they stop flickering for 20 then they flicker again and so on. Or they flicker for like a minute then they’re fine for a couple more minutes, then back again flickering. The timings vary a lot from house to house.
In my experience some brands of “dimmable” LED lights flicker and some do not. If you problems with flickering lights, try a different brand on that socket as an experiment. It might be the quality or type of components used.
Well written.
I think an important concept to introduce is Pulse Width Modulation, or PWM for short.
Normal AC Power coming out of wall looks like a sine wave, in that it smoothly cycles between +110/240V and -110/240V. This means that 50% of the time the voltage is positive and 50% of the time the voltage is negative.
PWM usually deals with signals which are either entirely on or off, with no transiton between them. This way, you can vary the amount of “power” delivered by varying how much of the time the signal is on and how much of the time it’s off.
Dimmers usually modify the sine way in a way that tries to accomplish the same thing, by chopping up the signal to make the effective “on” time be shorter than 50%.
With non-dimmable LEDs, this messes with the AC to DC circuitry in the lamp in the way slazer2au says, because the lamp doesn’t retain enough power between two on-cycles to stay on.
It’s because they aren’t installing the correct bulbs. Some dimmers work by cutting the ‘pulse’ that goes to the light early, some of them work by lowering the voltage/current.
When you install a direct LED to one that cuts the pulse, you get flickering. Incandescent bulbs don’t do this because they’re white-hot and don’t change luminosity fast enough for you to notice.
Basically: If they’re flickering – they did it wrong.
LED lights are either all on or all off, the only way to dim a LED, is to make it blink really fast and change the time it’s on vs the time it’s off. Cheap LED lights don’t blink fast enough, so you see them flicker.
That’s not the only way to dim an LED, just the cheapest. Variable current power regulators are the premium option.
A screw-in LED bulb combines LEDs and power regulating electronics. Some of them handle the variable input voltage a household dimmer provides gracefully, but that’s more expensive.
Changing the current can change the hue (color) of the led. In some cases it’s okay in some cases it isn’t. Cinema lights for instance don’t dim with voltage because of that. Instead they have 3 separate drivers synchronized to dim in a canon. One after the other so that there is always the same number of LEDs on at all time regardless of the dimmer level.
That’s true. Describing current regulation as the premium option was an oversimplification. For household lighting, it’s usually the premium option.
Dimmer switch limits the power. The light doesn’t like that.
Just wanted to let you know that there are a couple of eli5 communities. Just a sec- I’ll try to link.
Doh, two communities, but none for us who need it explained like we’re four. /s
Thanks! Just joined
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