At what frequency does the human eye notice flicker?

When you see a picture, hover the mouse pointer over it.

If the mouse pointer changes to an icon of a little white glove with a pointing finger, or something like that
this means the picture is also a clickable link.

In the case of the chart I posted, when you click the link, it takes you to the full article describing that chart and much else.
That chart is “Figure 3” and the text next to it says:

So the red line that rises from left to right is the light output — numbers along the left side of the picture (lumens)
The black line that decreases from left to right is the efficiency (efficacy, lumens per watt)
The text under the bottom of the chart explains that’s the forward current in milliAmps, increasing from left to right.

i said ignorant not stupid hank. i read the article and followed up with a post.

we have gotten way left field on this. All I am trying to do is find a way to constantly maintain the peak output of an LED.

I will try to think of another way to express my thoughts. What I am trying to accomplish is not impossible.

But I have learned a lot from everyone. Thanks

Ejected Filament wrote: I could be wrong, or half wrong but Im unlikely to be completely right. <<<<<< I love it

Well, that’s the easy part… just give it a constant stream of peak power… and some extreme cooling. :smiley:

You say the second link is of real interest. It is not.
Perhaps you should read the first comment on that link.

_ “Very clever, but that’s not how it works.

By your reasoning you should not only be able to make the frequency infinite, but also 4 Hz, or 100 Hz, or 2√

Hz, all at the same time, with the same signal. And that’s why you can’t do that: a repeating signal can have only 1 fundamental frequency, which is 1/period.

It would be the same as taking 2 periods of the 4 Hz sine and saying that that’s the period, because it also repeats, and then the signal would be 2 Hz. It can’t be 2 Hz and 4 Hz at the same time” _

Continue based on false and impossible concepts?
Because that is the only way to continue here.
You should go back and read every post in this thread,
trying to understand them rather than trying to refute them.

> Quote: I don’t what the red line is representing? or the dashed line.

Remember — online, we’re writing for an audience, and some readers won’t get here for days or weeks or months in the future

When one person doesn’t understand, likely others coming along later may also not understand. So it’s, I hope, worth explaining even though YOU got it quickly.

You’ll see — from me and others — explanations you may feel insult your intelligence. They’re not for you.

Being brighter than average, you may be offended by explanations intended for younger or new readers.

Sorry it bothered you. It wasn’t about you.

The average reading level of US citizens for nontechnical subjects is 7th grade — lower for anything technical.
So we try to explain things in ways people can follow even if they’re having a hard time.

1. Acquire array of high-efficacy LEDs (eg. 10 XHP70s)
2. Directly thermally bond them to a nitrogen-cooled, copper, convective heat exchanger. (Eg. big copper cold plate with liquid nitrogen circulating through it)
3. Power them with a high-current, low resistance power supply (eg. a big bank of LiPo batteries)
4. Use a gold-coated parabolic reflector to collect all of the light, and direct it outwards in a certain direction.

Then you will have the maximum possible light output.

…Not very portable though. :smiley:

Angler - I agree. Any result of this discussion can only be based on assumptions and premises established at the beginning of the discussion, and information included during. While the discussed information is interesting and valuable in other contexts, it is not truly pertinent to the discussion, because the basis of the discussion is flawed.
One cannot accurately answer a broken question.

Hank - good point well said.

Dehc111 - earlier, you said the following: “All I am trying to do is find a way to constantly maintain the peak output of an LED.
I will try to think of another way to express my thoughts. What I am trying to accomplish is not impossible.”
I think that is quite a good summation of this discussion, but not for the reasons you might think. Obtaining the most light from an LED is very simple; feed a highly efficant LED lots of power, and keep it cool. That is not rocket science. You’re right in a way; what you’re trying to accomplish is possible - it already exists.
This discussion appears to be predicated on you trying to re-invent the wheel.

I was trolling….

Just kidding.

Hank - ^5

Again thanks to everyone who posted to this thread. Very informative.

Regarding the efficiency peak, user Tobias Bessert at CPF in 2013 found a peak at about 160 mA for XM-L2 (that’s a bit higher than low mode in a 8x7135 Convoy S2+) and about 50 mA for XP-G2.
Not exactly bright, but an efficiency peak nevertheless. Thread: Using power LED at low current levels

–1

The DC line you so describe can in fact be “cut into pieces” by pulsing the DC current allowing “infinite” frequencies, with amplitude.

shareimprove this answer
answered Jul 20 ’14 at 3:14

Dr.Tim
1

I almost let you guys talk me out of my concept. Above is a comment made to the following reference link I posted earlier.

current - Is frequency for dc zero Hz? - Electrical Engineering Stack Exchange.

There seems to be a pretty solid understanding of electrical theory from the contributors to this thread but then again we are talking about electrical “THEORY”.

My idea is not flawed. Perhaps not defined correctly and my vernacular in error but the concept has merit .

Sure it can be cut into pieces. Commonly called PWM. Commonly used for dimming. Less efficient than constant current. Please elaborate on what everyone is wrong about.

And what exactly are you getting at when you say “electrical theory”?
It’s not something that is open to interpretation.
The properties of electricity are well known, understood, and documented.
You seem to have a penchant for wanting to rewrite this sort of thing.

Compare the reputations of the people posting comments at stackexchange. Weigh them.
One unidentifiable guy who posts a single comment ever isn’t a lot of support to rely upon.

I think I can boil this all down for you with a simple analogy.

You know string lights for christmas trees?
You know how they make those lights that chase, that is, light up in sequence?
I think this is analgous to the over-complicated thing you’re trying to say.

You see a set of chasing lights is less bright than a set of constantly lit bulbs.
Because all of the bulbs are not lit at the same time.
And yes it uses less electricity, because all of the bulbs are not on at the same time.

There is a direct correlation between electricity used and light emitted.

These two things can not be separated.

They can only be mitigated by using more efficient bulbs.

You are trying to dream up some type of more efficient electricity.

That is difficult to do. I have no idea who they may be although the last comment, and the one i quoted, was by a man who named himself “dr tim”.

The web sight itself seems legit and credible. I for one are not someone who thinks that something cant be done because I am told so. Throughout my life I have found that some things were indeed possible while most were as suggested not possible. If it were not for those of us who push the boundaries of the impossible then discovery would never exist. In the early twentieth century the head of the US Patent Office declined to issue any patents stating that everything had already been invented, or something to that effect.

I am not trying to reinvent the wheel as someone had suggested. Come to think of it though, the wheel has undergone many improvements over the years. Thank goodness, my car just wouldn’t be the same with rolling rocks under it.

You are comparing apples to wagon wheels. A Christmas tree string of lights is not plagued by heat, or limited power, or portability, or and end users quest to outshine the neighborhood unless your a Griswald.
On second thought the last string of lights i bought were LED.

Maybe the purpose of this discussion is to draw out alternatives that may be useful for other applications of the LED. I started this conversation looking for help to write an equation that would express the product for variables of a given problem.

Regardless of how flawed my idea may be, or technically impossible, or viably insignificant it is none the less a starting point for looking at something from a different perspective.

I completely understand why everyone thinks I am wrong and wasting my time on something that has already been worked on but here is my analogy: Why put multiple LED’s in a light when you can achieve the same thing from a single LED of higher power?

No, it is not difficult to do. Did you try?

Click on the userid/name of the person who posted the comment — it’s a link.

(In most browsers it will show up in a different color.)

Read the text that appears.

Compare “Dr Tim” whose (only, single ever, one) comment at the site seems to support you, to the reputations of the others commenting in the thread.

Weigh their reputations. I think Dr. Tim is having you on.

See also this.

I’m done with this one.

Your point, your purpose, your questions and your intent have changed numerous times over the course of this thread. Literally every single time you reply. First it was about maximum efficiency. Not much later it wasn’t about that at all, it was about maximum luminance.

Now you want to know why use multiple led’s in a light?

I dare not even answer because you will straightaway get to searching for a reason that the answer is wrong, ignoring established science and logic, continuing to go in circles. Unsubscribed.

> At what frequency does the human eye notice flicker?

those of us trained in detecting PWM can spot it below 1000 mhz
but an oscillator can tell with even higher values

> Okay so power management in LED’s is achieved by turning the led on and off so fast the human eye doesnt notice it

I do not think that is a correct definition of power management. It IS a definition of using PWM to dim a light

> the total “on time” is essentially reduced by 50%

yes, if you are using 50% PWM, but there are other variations. There are also pulses that do not drop all the way to Zero, hence not true PWM, but still pulsed. Zebralight is an example of a maker that uses pulses that do not drop to zero and most users cannot detect it by waving the light, or by photograph, but they still show on an oscilloscope

> therefore doubling the amount of time the LED can produce photons?

I do not follow that logic. If the LED is off half the time, it produces photons Half the time, not double.

I dont think I undertand your what your idea IS.

The comments are that your assumptions are not supported by fact. If you ask the wrong question, you get the wrong answer. Let me give you an example of a question that may not be valid:
“Do you still beat your wife?”
explanation, the assumption in the question is that you DID at one time beat your wife. This is (hopefully) flawed.

Similarly, your assumption in this thread is that LED power management REQUIRES PWM. I dont think that is accurate. I for one will NOT buy a light that uses PWM. I wont even buy a light that uses Pulses that dont drop to zero. Even if I cant see them, I do not choose to own lights that strobe my brain, even if I cannot consciously “see” the pulses.

To the best of my ability, I think your question is something like this.
Assume light with 4 LEDs. You want to Pulse them On and OFF at 50% on time, and you want the pulses to each light not be simultaneous. Sure, you CAN do that, but WHY?

Pulsing will NEVER produce as MUCH light as leaving the LED ON constantly.

PWM is a DIMMING strategy, designed to preserve the Tint of the output. PWM is NOT used on Maximum brightness modes.

I hope you take no offense at my attempt to point out what appears to be a contradiction of terms and assumptions.

Yes you can pulse leds independently, but WHY?