Flicker and LED Lights - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: December 03, 2014, 07:08:19 pm
content: I know LED lighting has been discussed in many threads, however I'm after some advice and thoughts on something a little different.I'm building a house at the moment and am yet to decide on lighting (it will be LED, just which one exactly is negotiable).My main concern is flicker (not necessarily noticeable to the human eye, but visible when using cameras as various shutter speeds). Some manufacturers (like Philips) advertise some of their lights as "flicker-free" but what does this mean? It is perceivably flicker-free to the human eye across the dimmable range or is it genuinely 100% flicker-free? Also, 240v vs low voltage DC; advantages/disadvantages?

author: Artlav
author_rank: Frequent Contributor
timestamp: December 03, 2014, 07:54:13 pm
content: If you can try the lights before you buy them, then a good test for flicker is to look straight at one, and move your eyes rapidly side to side.If the line is continuous, then there is no flicker to worry about.If you see dots (more likely when highly dimmed down), then you are in hundreds of Hz range, and there might be problems.If it's something like a tight zebra, then you're in low KHz range, and it's likely ok.Can't say much on HV or LV.I have a separate 24V wiring for my LEDs.One advantage is that you can hook them up to a battery backup with little extra effort (as little as a pair of diodes), while for 220V you'll need an inverter and to mess with mains voltage transfer switches or similar.An advantage of 220V ones would be that you can use standard lamps/sockets and have options to change your choice later.

author: tautech
author_rank: Super Contributor
timestamp: December 03, 2014, 08:09:47 pm
content: Just replaced halogen downlights in 2 rooms, total of 18 with 12 V 3 W MR11.Used existing fittings.I was hoping for plug & play but no.The older SMPS tranny supplies did not like the LED's , didn't flicker....flashed.So out to the bench to test these new units for current draw.....~ 45 mA.As I have a large ceiling space, time for some re-wire options I thought.I found driving up to 5 LED's with the old PSU's stopped the flashing but a visible vague flicker remained.Rewire time again, this time with a new 12 V "flicker free" downlight SMPS tranny wired with LV cabling and driving 10 LED units.FYI I have a 3 M stud height.Fixed.Now that room draws 1/10 th of the power to previously, lighting is whiter and very very uniform compare to the Halogens.Sparky who supplied the LED's & trannies did say my old trannies might flash or flicker, but I had to prove that for myself.EDITOnly checked this with 2 iPhone cameras, YES there are problems with flicker, the cameras randomly refocussing and occasionally visible flicker in their displays.Not visible to the naked eye though.Filming gurus will have the answers.Edit the thread title to attract these guys for comments.

author: SteveyG
author_rank: Unknown
timestamp: December 03, 2014, 08:18:36 pm
content: Quote from: Artlav on December 03, 2014, 07:54:13 pmI presume you mean LV and ELV.

author: Zero999
author_rank: Super Contributor
timestamp: December 03, 2014, 11:09:56 pm
content: The lamps in the videos I linked to in the other thread don't flicker, unless they were dimmed, even when the waveform was seen on an oscilloscope using a photodiode. The only problem was dimming but I don't believe those lamps were supposed to be dimable.https://www.eevblog.com/forum/reviews/led-filament-lamp-teardown/msg558243/#msg558243

author: cimmo
author_rank: Frequent Contributor
timestamp: December 04, 2014, 04:22:08 am
content: This guy does tests (often including a tear-down) of various LED lamps.One test includes a flicker test using a solar cell and oscilloscope.https://www.youtube.com/user/electronupdateWhilst the units he tests are from the North American market, some of the information may relate to locally obtainable LED lamps.