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Can someone ELI5 why often lights set up with a dimmer also flicker? (mander.xyz)

submitted 3 weeks ago by Mothra@mander.xyz to c/asklemmy@lemmy.ml

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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

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[–] Zak@lemmy.world 15 points 3 weeks ago (5 children)

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.

[–] LazaroFilm@lemmy.world 8 points 3 weeks ago* (last edited 3 weeks ago) (4 children)

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.

[–] demesisx@infosec.pub 8 points 2 weeks ago* (last edited 2 weeks ago) (2 children)

Hi Lazaro!

That’s not always true, actually. For example, Digital Sputnik lights (and some LED tape that I have that I use my current control dimmers on) utilize current control dimming. This alternative type of dimming allows them to work even with super high speed frame-rates due to having very little or even no perceivable flicker. It’s certainly unpopular in comparison to PWM but definitely not unheard of in the film industry.

I used to use the technique you mention with >2K tungsten lights for footage above 1000 fps. I figured out (in the absence of a budget that could afford a DC rectifier) that if I ran the same amount of lights on each of the legs of a 3 phase Delta style Gennie that they would effectively fill in each others’ pulses. I further enhanced that effect by shining all 6 5K’s (for example) on the same rag.

I used that technique here: https://youtu.be/w9-NoEnWSgk

[–] LazaroFilm@lemmy.world 3 points 2 weeks ago (1 children)

That’s awesome! I love how deep we are going with this! I have to admit I don’t k or as much about cinema lighting as I know about cameras and Steadicam.

[–] demesisx@infosec.pub 8 points 2 weeks ago

I’m happy to share any experiences I have had as we’re likely the only two filmmakers in the whole fediverse right now!

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