Again, I don’t think you’re going to see that in a real experiment. In reality, PWM has demonstrated itself to be less efficient than constant current. I don’t think there’s a special frequency that changes that. You haven’t given any plausible explanation why.
No, direct current does not operate in pulses. Alternating current is probably what you’re thinking of.
Earlier in your OP it was about minimal temperature and maximum efficiency.
But now that doesn’t matter because it’s about max luminous flux. Right?
And suddenly your flashlights operate on alternating current.
Are you trolling?
Did you even read that PWM is less efficient than Constant current in the quote I posted by Wight?
It doesn’t sound like he’s trolling. He’s putting in too much work for that.
I think he sounds more like someone trying to come up with a perpetual motion/energy design. That is, there’s no way to make it work, but some people won’t let that dissuade them.
I think(?) I understand what dehc111 is getting at.
Hypotheticals:
Yes we know that an LED is not at it’s most efficient when being pulsed at 6amps 50% cycle. 3amp CC is more efficient.
But let’s say the peak efficiency is at 2amps.
We could pulse 2amps at 50% cycle (net draw of 1amp) and in a perfect world it would be more efficient than running a constant current at 1amp.
The problem being that the pulse are not instant on/offs they are ramped with the LED not being as efficient on those ramps.
Am I getting both sides to an extent?
I agree that I think this is a fundamentally flawed venture.
You could easily calculate that if you want 6000 lumens, and your emitter does 800 lumens at it’s most efficient point, how many emitters and how much power you would need. No problem. But you still want to go CC, not pulsed.
The problem is that if LEDs have an efficiency peak, it’s at an extremely low current (at least for Cree). Take any led from http://pct.cree.com/dt/index.html , I’m pretty sure that for all tested currents the efficiency lm/W decreases as the current increases. Also the efficiency lm/A (Current), which would be useful if you use a linear driver, seems to decrease monotonically as the current increases. I believe that most if not all leds follow the same pattern.
Of no practical use, but … interesting
Also a very misleading title. All they’re doing is using heat from the environment to power the LED. It’s not greater than 100% efficiency.
LMAO AC batteries…. good one…… that made me lol for real.
I apologize as I didnt mean to abandon the topic…… At all. I am trying to find someone to understand where I am trying to take this. Between my poor vocabulary and marginal communication skills on the topic, slight ADHD ADD XYZ or wut ever i suffer from, I sincerely appreciate your attention. I assure you I am not trolling or the like. My time is as valuable as yours and in the end we will all have gained something from this.
Okay. All current does pulse. Let me define pulse I suppose. Pulsation is patterned vibration < down and dirty definition.
Matter of fact all matter in the known universe pulses. It is called resonate frequency. I wont go into an atomic theory here but this is a generally accepted concept.
Now that we have established that in fact DC current pulses lets explore managing or controlling this pulsation.
To keep the conversation focused I am trying to achieve maximum luminous output sustained. secondary would be efficiency and third heat.
I am not interested in perpetual energy or any far right experimental b.s. of the kind. (at least not in this thread on this forum)
Back to the equation… You think it has no relevance ? The values are not associative ? Please help me define which values are then.
Low current as compared to what?
Low current as compared to higher current, empirically, e.g.
See also
Okay but I don’t what the red line is representing? or the dashed line.
Good link Hank! Thank you.
The article discusses modifying the waveform to compensate for an AC circuit.
This is interesting because the AC mimics the on/off pwm this thread is exploring. What I find even more interesting about that article was the proposed change from 120mhz to 150mhz the EPA tried to mandate
because of a known negative effects or sensitivities that humans experience at ~ 120mhz.
Weaponize an LED’s in this frequency range? Isnt that the same frequency (120 mhz) that LED T.V.’s utilize for rendering high definition 1080P?
Okay that will make a great topic for another thread!!!
I knew there was some kind of relative association that exists.
Okay I need to think on this more so I can construct my questions from another perspective.
i can see 120hz flicker in cheap n nasty bulbs.
and cant stand low refresh rates in old crt pc monitors.worse when it beats with other lighting.which in the store was 4 tube t12 magnetic troffers.when we had pc’s on display at the shop i had to go around and reset all of them.otherwise it was like a room of strobes to me.
nobody but me and our tech could see this. this varies by the individual and reading that link also whether they have cirrosis.which i do not.
We have?
Not on my oscilloscope! :smiling_imp:
The resonant frequency of DC is zero.
lol. It would be a matter of semantics at this point.
I like you guys.
DC Current doesn’t resonate or pulse. Read again the first line of the Wikipedia article you linked:
We do see some resonance in our drivers at times, showing up as ringing. DEL told us how to fix that, so it shouldn’t be a problem with any of the newest drivers developed by PD68, TA, and others. 
My apologies if I sound rude, but I’m gonna be honest; those two sentences betray significant flaws in your understanding of the topic.
1. Energy efficiency and maximum luminous output are linked by the laws of thermodynamics. Efficiency and Efficacy are two separate variables, but again they are linked. To obtain the maximum possible light output, you must posses an LED with the maximum possible efficacy [approx 300lm/w], and then you must apply the maximum power possible to it (whilst keeping it’s efficacy constant by cooling it).
To even start talking about light output, you must first consider efficacy.
Relevant: http://m.phys.org/news/2010-08-white-super-high-luminous-efficacy.html
2. Direct current does not switch on and off, or vary in any oscillatory way. The word “Hertz” is to direct current what “quadrilateral” is to a circle. Absolutely unconnected.
But it helps everyone to discuss these things, so everyone can contribute positively to the discussion.
No need to apologize. As I stated. I am ignorant with poor communication skills.
Anyway we are veering away from where I was trying to keep this directed but I must let you know that you are both correct and incorrect.
I will cite two more references. The first of which more or less coincides with your response. The second is the one of real interest.
Now can we continue with the focal point?
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.