Okay I really like the conversation this has brought about. Everyone seems to have a valid point in some regard or another.
My point is this. If a flash of light lasts a known amount of time and is quantifiable in terms of brightness, temperature, current draw and is repeatable at lets say 500Mhz frequency, does the millisecond timing provide enough lapse for the LED to recover to cycle EXACTLY the same. YES because we haven’t put a limit on the millisecond recovery value.
Again, follow me on this: We all agree that the luminous output of an LED begins to diminish within milliseconds after being energized and reaching its apex output. That is the holy grail of LED performance. That single measure of time when an LED gives all it can. It is at that point the most efficient.
The performance curve.
Now explain to me that if an LED is on and off an equal amount of time during lets say a 1 minute frame at a rate 30 times per second that after 1 minute an equal amount of energy has been consumed from this arrangement as opposed to an LED that was provided constant current during the same. It may not use exactly half as much energy but indeed significantly less.
But this isnt about energy, this is about achieving maximum luminous output.
energy efficiency is a bonus.
Btw, constant current indeed operates in pulses. All electrical current does. Hertz….its how we measure it.
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.
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.
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.
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.
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.
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.
