4 ms·

I think this probably concerns many more people than are aware of it. I could live with the flickering but I live better by doing what OP did, set screen bright

I think this probably concerns many more people than are aware of it. I could live with the flickering but I live better by doing what OP did, set screen brightness to max, on all of my laptops and external LCD screens. I then use redshift (I'm on Linux)[1] to dim the screen to the desired brightness, i.e. absorb the excess light in the liquid crystal layer. Sadly this does appear to lead to some loss in brilliance and color quality, but it's not too bad, and I like that I never have to see the flickering. I know someone who puts a foil based filter in front of the screen, that may work somewhat better, I still haven't tried that myself. I find it frustrating how almost all LED lighting installed in the UK is PWM based (if dimmed), or otherwise flickering (AC), too. And it's just a question of consumer expectation: if you buy an LED light bulb in a standard shop in Switzerland, it doesn't flicker, if you buy one in the UK, it does. Both bulbs use the new LED filaments, you can't tell the difference from looking at the bulbs, the difference is in how the power supply in the base of the bulb works. I opened up one of the Swiss bulbs and it had a proper switched-mode power supply (using a switching frequency probably in the 100 KHz range); I saw a video on Youtube by someone who opened up one of the UK ones, and the power supply was based on current limiting via capacitors (and then a rectifier), which leads to a flicker at twice the AC frequency (hence 100 Hz). There's going to be a cost difference of £1 or so, the Swiss consumers are apparently ready to pay for that, the UK population not (or the UK shops possibly pocket the savings). [1] https://en.wikipedia.org/wiki/Redshift_(software) https://en.wikipedia.org/wiki/Redshift_(software) (actually still using the command-line variant of an older version, e.g. "redshift -b 1 -g 0.9:0.9:0.9 -l $POS -t 5500:4800")

Zak 9y ago
A lot of cheap mains-powered LEDs aren't using PWM, but running on mains power directly. You can test whether this is the case using a smartphone camera and an app with manual shutter speed control. If you see scanlines just above and below, but not at 1/50s, your light source is flickering at 50 Hz, which is the AC frequency of UK mains power.
- pflanze 9y ago
  > A lot of cheap mains-powered LEDs aren't using PWM, but running on mains power directly. Yes, I just added information about that to my comment, sorry for the race condition.
yardie 9y ago
Could this be a difference in the dimmer. I’m in the US (120V vs 240V) and I had research carefully what dimmers were compatible with the dimmable LEDs in our flat. Sometimes the dimmer would hum, the LEDs would squeal, or they would go from 0 to 100% with 20% dimming. Most LEDs are made in China and I doubt the Swiss are getting a specially manufactured ones. But old, incompatible dimmers are definitely a thing.
- pflanze 9y ago
  No external dimmers were involved. As I wrote, I opened up a bulb myself (sawed off the tip of the base) and saw electronic parts consistent with a switch mode power supply (dozens of parts including rectifier, capacitor, tiny transformer, rectifier, capacitor, IC for controlling it). I know I saw something different than was in the video for the UK version! No reason China can't produce both.
- Zak 9y ago
  It's not the LEDs themselves that are a problem there, but the driver circuitry in the "bulb"[0]. There are a fair number of these being made in the US and Europe, not just China. Significant numbers of LEDs are also made outside China - Cree manufactures LEDs in both the US and China; Nichia manufactures LEDs in Japan. [0] Bulb is not really an accurate term here. Maybe bulb-replacement?
walterbell 9y ago
Iris claims to perform brightness adjustments in software (GPU?), allowing the monitor’s PWM brightness to stay at 100%, for Win/Mac/Linux: https://iristech.co/iris/ https://iristech.co/iris/ I'm wondering if the Iris approach affects color accuracy, otherwise why wouldn't MS/Apple use the same technique?
- systoll 9y ago
  The Iris approach lowers the device’s battery life, and the screen’s contrast ratio.
gm-conspiracy 9y ago
I find newer cars' brake lights at night very annoying with their PWM "trails".

Zak 9y ago

A lot of cheap mains-powered LEDs aren't using PWM, but running on mains power directly. You can test whether this is the case using a smartphone camera and an app with manual shutter speed control. If you see scanlines just above and below, but not at 1/50s, your light source is flickering at 50 Hz, which is the AC frequency of UK mains power.

pflanze 9y ago
> A lot of cheap mains-powered LEDs aren't using PWM, but running on mains power directly. Yes, I just added information about that to my comment, sorry for the race condition.

yardie 9y ago

Could this be a difference in the dimmer. I’m in the US (120V vs 240V) and I had research carefully what dimmers were compatible with the dimmable LEDs in our flat. Sometimes the dimmer would hum, the LEDs would squeal, or they would go from 0 to 100% with 20% dimming. Most LEDs are made in China and I doubt the Swiss are getting a specially manufactured ones. But old, incompatible dimmers are definitely a thing.

pflanze 9y ago
No external dimmers were involved. As I wrote, I opened up a bulb myself (sawed off the tip of the base) and saw electronic parts consistent with a switch mode power supply (dozens of parts including rectifier, capacitor, tiny transformer, rectifier, capacitor, IC for controlling it). I know I saw something different than was in the video for the UK version! No reason China can't produce both.
Zak 9y ago
It's not the LEDs themselves that are a problem there, but the driver circuitry in the "bulb"[0]. There are a fair number of these being made in the US and Europe, not just China. Significant numbers of LEDs are also made outside China - Cree manufactures LEDs in both the US and China; Nichia manufactures LEDs in Japan. [0] Bulb is not really an accurate term here. Maybe bulb-replacement?

walterbell 9y ago

Iris claims to perform brightness adjustments in software (GPU?), allowing the monitor’s PWM brightness to stay at 100%, for Win/Mac/Linux: https://iristech.co/iris/ https://iristech.co/iris/ I'm wondering if the Iris approach affects color accuracy, otherwise why wouldn't MS/Apple use the same technique?

systoll 9y ago
The Iris approach lowers the device’s battery life, and the screen’s contrast ratio.

gm-conspiracy 9y ago

I find newer cars' brake lights at night very annoying with their PWM "trails".