why do LED bulbs flicker now.   They use to be stable - Page 1
Forum section: electronics / general

author: snarkysparky
author_rank: Frequent Contributor
timestamp: March 10, 2024, 10:17:01 pm
content: Can't seem to find any on the shelf that don't flicker.how do they get out of manufacturing like this?Seems like a case of let them eat cake.

author: BrianHG
author_rank: Super Contributor
timestamp: March 10, 2024, 10:24:35 pm
content: Please watch this: (he measures the flicker index, temp & CRI)

author: BrianHG
author_rank: Super Contributor
timestamp: March 10, 2024, 10:34:41 pm
content: Just in case you didn't get the message in the video, just buy the 'Philips Ultra Definition' bulb.View the video in Youtube, and you will see his Amazon link to the Philips bulb in the video description.

author: Halcyon
author_rank: Unknown
timestamp: March 10, 2024, 11:51:19 pm
content: Most LED lamps have had some kind of flicker for as long as I can remember. Some visible, some not.When I built my house about 8 years ago, I did research into bulbs with the least amount of flicker. ledbenchmark.com is a good resource I used at the time.Maybe there is just a bigger range of cheaper/crappier bulbs out there now?

author: floobydust
author_rank: Super Contributor
timestamp: March 11, 2024, 12:34:24 am
content: Quote from: BrianHG on March 10, 2024, 10:34:41 pmI stopped buying $8 LED bulbs a long time ago. The engineer in me thought they would meet their potential, but landfill is really where they all ended up. Even the Cree ones were dogs."Philips Ultra Definition" atHome DepotCAD $8 FFS too expensive. Ikea is $1 bulb on sale and they are lasting quite a long time.Philips does make some shitty LED bulbs, lucky to get 2 years out of them and I took it apart and was appalled at how cheap it was.They used to use several LED's and now it's just a single COB- which is terrible for half-angle, it's just a spot. It's too bad, they did have the best CRI I'd seen.Why LED's bulbs blink blink blink?I've found two reasons - the LED dies are glued onto the substrate and this does not take heat well. The heating and cooling cycle of the disconnect that happens makes an oscillator. It's the glue.Second reason is the LED driver electrolytic capacitors dry out and the PSU just sits and blink blink blinks.As I keep saying, the sea of patents and litigation prevent a manufacturer from making a really good LED bulb. A crime against humanity really.

author: BrianHG
author_rank: Super Contributor
timestamp: March 11, 2024, 01:06:00 am
content: Quote from: floobydust on March 11, 2024, 12:34:24 amYes, home depot is a ripoff. At Amazon, at least they are 5.80$ CAD a bulb.If a 1$ bulb works for you, then do not spend a penny more.In my kitchen and hallway, my el-cheapo 1$ bulbs keep on blowing after around 6-9 months. All at once, they will go dim then flickering. Most likely a surge during power-on destroying the cap dropper style supply. At least the 6$ switching supply type bulb so far hasn't died. In my bedrooms, the 1$ bulbs seem to have lasted years fine.

author: snarkysparky
author_rank: Frequent Contributor
timestamp: March 11, 2024, 01:12:58 am
content: Thinking about making my own lighting.Get LED pucks and mount them to a good heatsink. Run them at half rated power from a DC supply.It making this PURDY that will be the problem.

author: soldar
author_rank: Super Contributor
timestamp: March 11, 2024, 01:30:35 am
content: In my experience they are being overdriven.I have also discovered that they can be easily dimmed with just a resistor in series. No need for complex circuits.

author: floobydust
author_rank: Super Contributor
timestamp: March 11, 2024, 01:37:56 am
content: I've mentioned before, an interesting study- 'Lifetime Testing of Light Emitting Diodes and LED Products June 2021' Good read that explains many failures.https://www.iea-4e.org/ssl/our-work/led-lifetime-test-report/Report PDFhttps://www.iea-4e.org/wp-content/uploads/publications/2021/06/SSL-Annex-Lifetime-Literature-Review-Report-by-the-LRC_final.pdfI think the latest stuff is behind their paywall.Operating temps can be very high, some over 100°C. Some bulbs (MR-16) it's the driver electronics that usually fail.Temperature cycling from turning the bulbs on and off greatly shortens lifetime. Cracked PCB solder joints and LED bonding wires."The times to catastrophic failure were zero failures for 80°C, 7,000 hours for 90°C, and 1,100 hours for 100°C. These results emphasize the need to include power cycling as an independent variable in LED system life tests. The number of cycles to failure is not a relevant parameter in this case."

author: amyk
author_rank: Super Contributor
timestamp: March 11, 2024, 02:31:52 am
content: Not enough, or even completely absent capacitors on the DC output.

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 11, 2024, 02:58:11 am
content: Mostly just race to the bottom modern corporate management BS. The Phillips ultra whatever do make nice light, warm when dimmed, etc. Closest to a real tungsten lamp I've ever seen, including one failing in under a month, in an open fixture, looked like a driver failure.The GE HD bulbs ran hot and 75% died in under a year, they didn't even silicone the diffusers on good.Most reliable I've seen were "Earth bulb", one of the first low cost options ($5 each), oldest I have are probably a decade old, some very high hour (noticably dim but still working), only one failure, recently, big heavy buck converter driver. Also the 100 watt equivalent Dollar Tree bulbs (hard to beat $1.25 for 1500 lumen 14 watts), I use those in utility/work areas to brighten them up, haven't killed one yet, even have a pair in an outdoor security light, only protected from direct rain, other than some yellowing of the diffusers they're fine 2 years later. Also being the linear regulator type they're dead quiet.

author: wraper
author_rank: Unknown
timestamp: March 11, 2024, 03:02:53 am
content: In EU it's now illegal to sell any bulbs that significantly flicker, so any bulb sold here is at least half-decent in this regard. There is no such regulation for floodlights though and most of them are flickering garbage. Also each LED bulb must have standardized information sheet where you can check actual flicker specs. It's often present on manufacturer website and online stores. However if it's not there, there is also public databasehttps://eprel.ec.europa.eu/screen/product/lightsourceswhere you can find every bulb legally sold here as long as you know model identifier than can be found on the box. Although what's not helpful about this is that manufacturers often just specify max permissible flicker and stroboscopic effect specs (Pst/SVM) instead of actual figure.

author: floobydust
author_rank: Super Contributor
timestamp: March 11, 2024, 03:50:36 am
content: Quote from: BrokenYugo on March 11, 2024, 02:58:11 amIt's worse than that - you haveFeit,Nichia, Seoul Semi, Cree, Ledvance etc. all suing each other over patent infringement. For years now.Even that's not enough - then they also sue the retailers like Wal-Mart, Home Depot, ACE Hardware etc. for selling the "infringing" products.I can't imagine how to design a reasonable, decent LED bulb with so many patents on heatsinking and LED configuration. This nonsense needs to be open for the planet's good and instead we have blink blink blink blink boing landfill for these "50,000 hour life" electronics that incandescent bulbs end up giving them a run on lifetime.Feit filament style LED lamp patent enforcementwhite not yellow. Jees

author: EPAIII
author_rank: Super Contributor
timestamp: March 11, 2024, 10:23:29 am
content: Individual LEDs always have flickered. I used one years ago to replace a neon strobe light in a turntable. It worked like a charm. Individual LEDs can turn on and off at a rapid rate so all I had to do was drop the Voltage down and use a full wave rectifier WITH NO FILTERING. It "strobed" at 120 Hz, just like the original neon bulb did.The assemblies that are commonly called LED bulbs today have a number of individual LEDs in them along with some circuitry that allows a 2 or 3 Volt DC device to function on 115 VAC. That circuitry would be what determines how much flicker you see, not the LEDs themselves. The LED bulb will draw around 50 mA, +/- depending on the exact equivalent Wattage. That current determines the size of the filter capacitor needed to smooth out the peaks and eliminate the flicker. If the manufacturer skimps on that capacitor, then you get flicker. Likewise if they use a choke instead of a capacitor.It's that simple.

author: tom66
author_rank: Super Contributor
timestamp: March 11, 2024, 10:31:10 am
content: Dimmable LED bulbs, in my experience, tend to flicker more. This is because to add the dimming capability, they usually modulate the LED current to be in proportion to the input sine wave. If a triac-chopped dimmer is used the result is a dimmed bulb = happy user. However, any 'crap' on the power line will also be picked up by this circuit as it tends to have a quick response.I would suggest seeking out non-dimmable bulbs. In my experience they are flicker-free, I have done high speed photography (480fps) under a new LED bulb from Costco and there was essentially no flicker visible from the bulb. It unfortunately may only be something you can determine by experimentation as it is not usually marketed.

author: jmelson
author_rank: Super Contributor
timestamp: March 12, 2024, 01:14:16 am
content: Quote from: snarkysparky on March 11, 2024, 01:12:58 amI did this in 2014 in my kitchen. They are STILL going strong. I did use a commercial LED power supply. Since the LEDs dim for several seconds after power-off, I know they have some decent capacitors in those power supplies.http://pico-systems.com/Lighting.htmlJon

author: twospoons
author_rank: Frequent Contributor
timestamp: March 12, 2024, 01:57:47 am
content: Quote from: snarkysparky on March 11, 2024, 01:12:58 amAnd I did it for my wife's painting studio - so I could use 98 CRI LEDs, a solid heatsink, and pick a decent driver. Chose the driver off Aliexpress based on the number of capacitors I could see in the picSeems to have worked out well so far - at least 5 years.All of which goes to show its not the LEDs which are bad, but the 'race to the bottom' design philosophy of so many companies and consumer unwillingness to pay for quality.

author: EPAIII
author_rank: Super Contributor
timestamp: March 12, 2024, 02:20:30 am
content: I have 39 four foot florescent style LED tubes in my home and shop and have seen the after-glow. That after-glow may be more due to the phosphors they coat the LEDs with to get the spectrum they want/need than to the capacitors. With a 120 Hz (100 Hz for many) rectified power line frequency, the capacitors only need to hold a charge for around 10 cycles to overcome flicker. The manufacturers are unlikely to use a capacitor that will keep the LEDs glowing for several seconds which is 10 to 50 times longer.PS: My four foot LED tubes are Sunco brand which I purchased on the internet. Their prices are not the cheapest: I could have purchased four footers locally for 1/2 to 1/4 of that price. But the Sunco tubes have been working for several years and I have not needed to replace a single one. And there is no noticeable flicker. I am sure I have saved the purchase price in my electric bill at least two times over. I do recommend them.Quote from: jmelson on March 12, 2024, 01:14:16 am

author: EPAIII
author_rank: Super Contributor
timestamp: March 12, 2024, 02:27:33 am
content: For better or worse, most consumers are not educated to the point where they understand the differences. They do buy LED lighting because it is more efficient so they get lower electric bills. Beyond that they only see the claims on the package and you are lucky if they understand the difference between "warm" and "cool" bulbs.The other things could be taught in schools; secondary/high schools would probably be the best choice. In fact a course in "practical decision making" would probably be a better subject than a history course where the instructor only asks for a bunch of dates on the exams.Quote from: twospoons on March 12, 2024, 01:57:47 am

author: 5U4GB
author_rank: Super Contributor
timestamp: March 12, 2024, 02:43:18 am
content: If you want to DIY the checking, you can get plastic grating spectroscopes for a few dollars from your favourite crapvendor and can check for flicker with, from memory, a fidget spinner, acting as a cheap timing stroboscope. Some years ago when we needed new lighting I went into a local hardware store with those two and checked the various display lights until I found one that had no flicker and was perfectly daylight-balanced, then got that. It's a few dollars invested up-front but then you know exactly what you're getting.

author: tom66
author_rank: Super Contributor
timestamp: March 12, 2024, 10:30:42 am
content: Chances are if someone needs high CRI or a specific colour temperature they will know that they need that. Few people benefit from >90 CRI (which most cheap LED bulbs can achieve anyway) in normal use.