[WalterBright]

I know. But when I was programming LEDs for my single board computer, I found that blinking the LEDs used a lot less power. If the blink rate was fast enough, your eye did not distinguish that from the LED being on 100% of the time.

I don't know if battery powered devices generally use that trick or not.

[dylan604]

all dimmable LEDs use blinking, but interesting case for your suggestion for an even more efficient use of a "steady" LED. what blink frequency did you use to keep it from being visible to the eye? did it not dim the overall brightness to a meter? early LEDs were atrocious with their slow blink rates that quickly scanning across them could see it, but even more noticeable if you pointed your camera at them. now, they blink incredibly fast, fast enough even for some slo-mo to not strobe.

[CableNinja]

You only need about 40hz to make it seem on all the time, TVs (before 2020, maybe earlier) only did 25hz-ish. You can actually play pretty ridiculous tricks on the brain if you know this. For example, in VR, in a large enough room, you can slightly alter the angle the player sees inbetween frames. This alteration makes the brain think youre slightly offset from where it thinks you should actually be. This allows you to cause a person to walk in a circle irl, while they think they are walking in a straight line. Unfortunately only works up to a threshold of change, before the brain starts getting confused and causss the user motion sickness.

[user_7832]

Fwiw, these "tricks" are nice for some, but cause headaches for those who're PWM sensitive (like me). I can easily see the flicker of eg my Pixel 5 screen (which iirc is around 300ish hz?), and it hurts my eyes.

Fortunately, some folks like Philips make bulbs that are very low or zero flicker.

[dylan604]

>TVs (before 2020, maybe earlier) only did 25hz-ish

tell me your European without telling me.

> You can actually play pretty ridiculous tricks on the brain if you know this.

I do random persistence of vision tricks all the time. I can see flickering in cheap CFLs or old tubes with bad ballast, and now with LEDs seeing the cheaper controllers with slow blink rates. Once you know how, the brain is a dumb rube waiting to be tricked. Only believe half of what you hear and none of what you see.

[WalterBright]

Oh, I just hooked it up to a square wave generator and an oscilloscope. I just played with the square wave frequency. It was 50 years ago, I don't recall values and such.

[yjftsjthsd-h]

I mean, that's just PWM dimming, right? AIUI, pretty well ubiquitous for all LED dimming, including battery-powered.