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i need sleep (sh.itjust.works)

submitted 6 days ago by einfach_orangensaft@sh.itjust.works to c/science_memes@mander.xyz

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[-] anothercatgirl@lemmy.blahaj.zone 41 points 6 days ago

noise machine

[-] kbobabob@lemmy.dbzer0.com 21 points 5 days ago

Turn the lights off when you go to bed.

[-] Xerxos@lemmy.ml 1 points 5 days ago

Are they from Toshi Station?

[+] LodeMike@lemmy.today -6 points 6 days ago

No it's not lol they still flicker out eyes just dont pick it up

[-] Hope@lemmy.world 105 points 6 days ago

It has a 60Hz electric waveform in, and it produces visible light, which is in part a ~500THz wave.

[-] sik0fewl@piefed.ca 3 points 6 days ago

Do you think we will ever change our power grid to have a higher frequency so that our bulbs don’t flicker when we record things?

[-] Assassassin@lemmy.dbzer0.com 18 points 5 days ago

Good LED bulbs have a smoothing capacitor after the full bridge rectifier. This allows the LED to maintain most of its output during the low points in the cycle, resulting in minimal to no flicker when recording.

[-] MOCVD@mander.xyz 13 points 5 days ago

Alright, show me your eyebrows

[-] Cort@lemmy.world 6 points 5 days ago

Implying there's more than one

[-] Assassassin@lemmy.dbzer0.com 7 points 5 days ago

Peh chu chu peh chu chu peh monobrow wiggle

[-] SkunkWorkz@lemmy.world 4 points 5 days ago

He electrocuted himself

[-] hereiamagain@sh.itjust.works 5 points 5 days ago

I loled

[-] flyingSock@feddit.org 23 points 6 days ago

Buffer the input in a battery then use dc out from the battery to power your lights, no flickering. No need to reconfigure the entire grid and every device on it for niche applications.

[-] iSeth@lemmy.ml 5 points 5 days ago

Just rectify the AC, if the voltage isn't too much.

You don't need a buffer unless the power fluctuates.

Not a licensed electrician

[-] hereiamagain@sh.itjust.works 6 points 5 days ago

Rectifying the AC, even with a full bridge rectifier, will still drop to zero every time the AC voltage crosses the zero line. So usually a capacitor is added to buffer this output. Its capacity depends on the size of the load.

[-] iSeth@lemmy.ml 1 points 4 days ago

Good point. Pulsed isn't for everything

[-] qjkxbmwvz@startrek.website 15 points 6 days ago

High frequency is generally bad for transmission line losses, so getting power from A to B is better at lower frequency

DC is a great option here.

If we switched to DC, many things would still flicker though as they would presumably use switching power supplies, but those could be relatively high frequency like you said.

Interestingly, airplanes use 400Hz, as transmission over distance doesn't matter, and transformers can be made much smaller/lighter.

[-] FishFace@piefed.social 8 points 6 days ago

Also if we switched to DC, you'd need costly dcdc transformers to step up the voltage for transmission and back down again for domestic usage

[-] NotANumber@lemmy.dbzer0.com 2 points 5 days ago

Aren't switching mode power supplies smaller and more efficient than regular AC transformers anyway?

[-] FishFace@piefed.social 4 points 5 days ago

As far as I understand, a DCDC converter is less efficient and more expensive than an equivalent ACAC converter. I don't know about switching power supplies, and whether that's true or extendable to the transformer case, sorry.

Long distance point to point power transmission (like internationally) is often DC because transmission losses become more important.

[-] NotANumber@lemmy.dbzer0.com 1 points 5 days ago

I don't think that's actually true. To do AC to AC conversion at grid frequencies normally requires large inefficient transformers. A PC power supply is an example of a switch mode power supply. Basically what happens is: AC mains -> DC (at mains voltage) -> AC (high frequency, mains voltage) -> transformer -> AC (low voltage, still high frequency) -> DC (low voltage). Why do all this? Because doing the voltage conversion at grid frequency would need a much bigger transformer. They could just do the voltage conversion at grid frequency and only have to rectify once with no conversion back to ac, but it's actually less efficient and requires more expensive hardware. So actually DC to DC conversion is more efficient, even if it means using high frequency AC in the middle. Not all switch mode supplies use this AC trick, though they do all involve switching current. buck and boost converters are used in smartphones, laptops, motherboards don't have any transformer and are incredibly compact and efficient.The fact that many many things also need DC would be a bonus. Recitifying single phase AC at low frequency is not the most efficient thing in the world. Three phase is better, but having straight DC and only needing to change voltage would probably be best.

[-] FishFace@piefed.social 1 points 5 days ago

I am reading 99.5% efficiency in AC-AC transformers, and up to 95% efficiency in DC-DC converters.

[-] adb@lemmy.ml 2 points 5 days ago

They’re more efficient than old school ac-dc linear supplies (of which an ac transformer is just a part of). However if you just want to step up or down ac voltage, transformers are quite efficient.

[-] stupidcasey@lemmy.world 6 points 6 days ago* (last edited 6 days ago)

But we could just attach an antenna to our roofs and steal electricity, I consider it worth the transmission loss if we can create more transmission loss.

[-] socsa@piefed.social 3 points 5 days ago

Even a switch mode power supply doesn't really flicker since they have a rectification and smoothing stage on the output to produce a DC voltage. The switching is done on the input to set the duty cycle which controls the voltage/current ratio at the output.

[-] Thunderbird4@lemmy.world 5 points 5 days ago

If lights are flickering when you record videos, you probably need to change the settings on your camera to match your country’s grid frequency. Almost every video recording device will have a 50/60Hz setting somewhere.

[-] Tehdastehdas@piefed.social 5 points 6 days ago

How about banning flickering lamps? I'd ban screeching power adapters too.

[-] socsa@piefed.social 30 points 5 days ago

For incandescent bulbs the power drop around the zero voltage cross doesn't last long enough to extinguish the filament, since it's basically just glowing from being heated. The only lights which actually do "flicker" under nominal conditions are old ballast driven florescent lights. Most modern LEDs rectify the AC and modern CFLs boost the line frequency to like 20kHz to prevent the arc from getting extinguished.

[-] Sasquatch@lemmy.ml 1 points 3 days ago

A lot of christmas lights still flicker. Not sure how they're wired, but I think they just feed AC to the diode, so it's off for the negative half of the wave

[-] deltapi@lemmy.world 3 points 5 days ago

Modern CFLs use an arc? I thought they were cathode based, emitting UV from forcing mercury vapour to dance

[-] Hadriscus@jlai.lu 2 points 4 days ago

mercury vapour dances ?!

[-] NeatNit@discuss.tchncs.de 30 points 6 days ago

Incandescent bulbs like that in the picture don't really flicker. They might pulsate a little bit but even at their faintest they would still have significant light output.

Some LED bulbs do flicker though, it depends on how they implement the AC to DC conversion. If they flicker, it is easily noticeable to the human eye, especially when looking at motion.