A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings,
than the DC operation, but people in the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating
intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and
it definitely exhibited an afterglow of a full 45 seconds after power was removed, not uniform across a bulb population, but close enough. It is definitely using persistent phosphors. Needless to say one would need a laboratory grade high sensitivity instrument to detect any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but peoplein the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but peoplein the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs ><bloggs.fredbloggs.fred@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where
they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but people in
the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now
recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it definitely
exhibited an afterglow of a full 45 seconds after power was removed, not uniform across a bulb population, but close enough. It is
definitely using persistent phosphors. Needless to say one would need a laboratory grade high sensitivity instrument to detect
any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible >afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker
will kill you. Avoid all rapid eye movements, ditto sure death.
Campfires flicker and are lethal too.
On 12/09/2023 12:58, Fred Bloggs wrote:people in the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979Did you switch off at the AC mains or interrupt the feed directly to the LEDs - in other words is the afterglow from phosphors or internal
capacitor discharge or maybe even both?
piglet
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:in the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but people
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker
will kill you. Avoid all rapid eye movements, ditto sure death.
Campfires flicker and are lethal too.
On a sunny day (Tue, 12 Sep 2023 07:05:48 -0700) it happened John Larkin <jjla...@highlandtechnology.com> wrote in
<78r0git8l1kh3kt9q...@4ax.com>:
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs ><bloggs.fred...@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where
they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but people in
the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now
recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it definitely
exhibited an afterglow of a full 45 seconds after power was removed, not uniform across a bulb population, but close enough. It is
definitely using persistent phosphors. Needless to say one would need a laboratory grade high sensitivity instrument to detect
any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible >afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker >will kill you. Avoid all rapid eye movements, ditto sure death.I think my monitor has a LED backlight, it changes brightness all the time when working.
Campfires flicker and are lethal too.
Same for my laptop.
But I did switch off the auto brightness feature in the laptop,
annoying changing all the time.
And my room LED lighting is in fact PWM controlled: https://panteltje.nl/panteltje/pic/ethernet_color_pic/
Some LED lights have no converter chip but run directly from AC, https://panteltje.nl/pub/LED_light_circuit_diagram_IMG_6925.JPG
the capacitor on the left limits the current
So any current spike will cause a flash.. and kill the LED as in my case.
So avoid that type.
https://panteltje.nl/pub/LED_light_fix_IMG_6918.JPG
On a sunny day (Tue, 12 Sep 2023 07:05:48 -0700) it happened John Larkin <jjla...@highlandtechnology.com> wrote in
<78r0git8l1kh3kt9q...@4ax.com>:
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs ><bloggs.fred...@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where
they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but people in
the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now
recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it definitely
exhibited an afterglow of a full 45 seconds after power was removed, not uniform across a bulb population, but close enough. It is
definitely using persistent phosphors. Needless to say one would need a laboratory grade high sensitivity instrument to detect
any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible >afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker >will kill you. Avoid all rapid eye movements, ditto sure death.I think my monitor has a LED backlight, it changes brightness all the time when working.
Campfires flicker and are lethal too.
Same for my laptop.
But I did switch off the auto brightness feature in the laptop,
annoying changing all the time.
And my room LED lighting is in fact PWM controlled: https://panteltje.nl/panteltje/pic/ethernet_color_pic/
Some LED lights have no converter chip but run directly from AC, https://panteltje.nl/pub/LED_light_circuit_diagram_IMG_6925.JPG
the capacitor on the left limits the current
So any current spike will cause a flash.. and kill the LED as in my case.
So avoid that type.
https://panteltje.nl/pub/LED_light_fix_IMG_6918.JPG
On Tuesday, September 12, 2023 at 10:06:06?AM UTC-4, John Larkin wrote:people in the industry have reached this conclusion. AC operation has the drawback of flicker, fluctuating intensity, which is now recognized as a health hazard, so it must be reduced/eliminated. Was just scoping out a small mains powered bulb, and it
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot of physics and chemistry involved. I'm not sure where they're getting AC LED operation promises greater efficiency, reliability, and cost savings, than the DC operation, but
for same purpose. They're not real expensive, but definitely not cheap for the application.Another terrifying health hazard!
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Powers that be could be transmitting power line signals used to control you.
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around
5 ns resolution.
There are landscape pebbles, look like ordinary pebbles, treated with something that is charged by sunlight during the daytime and then emit light in the dark. Used for lighting pathways at night, or aquariums. Same technology is used in paving stones
On Tuesday, September 12, 2023 at 11:12:14 AM UTC-4, Jan Panteltje =
wrote:
On a sunny day (Tue, 12 Sep 2023 07:05:48 -0700) it happened John Larkin=
<jjla...@highlandtechnology.com> wrote inlaboratory grade high sensitivity instrument to detect
<78r0git8l1kh3kt9q...@4ax.com>:
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot = >of physics and chemistry involved. I'm not sure where
they're getting AC LED operation promises greater efficiency, reliabili= >ty, and cost savings, than the DC operation, but people in
the industry have reached this conclusion. AC operation has the drawbac= >k of flicker, fluctuating intensity, which is now
recognized as a health hazard, so it must be reduced/eliminated. Was ju= >st scoping out a small mains powered bulb, and it definitely
exhibited an afterglow of a full 45 seconds after power was removed, no= >t uniform across a bulb population, but close enough. It is
definitely using persistent phosphors. Needless to say one would need a=
any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around=
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible
afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker=
will kill you. Avoid all rapid eye movements, ditto sure death.I think my monitor has a LED backlight, it changes brightness all the tim= >e
Campfires flicker and are lethal too.
when working.
Same for my laptop.
But I did switch off the auto brightness feature in the laptop,
annoying changing all the time.
And my room LED lighting is in fact PWM controlled:
https://panteltje.nl/panteltje/pic/ethernet_color_pic/
Some LED lights have no converter chip but run directly from AC,
https://panteltje.nl/pub/LED_light_circuit_diagram_IMG_6925.JPG
the capacitor on the left limits the current
So any current spike will cause a flash.. and kill the LED as in my case.=
So avoid that type.
https://panteltje.nl/pub/LED_light_fix_IMG_6918.JPG
This Chinese special looks a little more robust:
https://ledask.com/ezoimgfmt/www.ourpcb.com/wp-content/uploads/2021/08/QQ%E6%88%AA%E5%9B%BE20210819113943.jpg
Almost incoherent write-up here:
https://ledask.com/led-bulb-circuit/
No wonder their crummy bulbs flicker.
On Tuesday, September 12, 2023 at 11:12:14 AM UTC-4, Jan Panteltje =
wrote:
On a sunny day (Tue, 12 Sep 2023 07:05:48 -0700) it happened John Larkin=
<jjla...@highlandtechnology.com> wrote inlaboratory grade high sensitivity instrument to detect
<78r0git8l1kh3kt9q...@4ax.com>:
On Tue, 12 Sep 2023 04:58:12 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
A LED is not just a light emitting semi junction, there is quite a lot = >of physics and chemistry involved. I'm not sure where
they're getting AC LED operation promises greater efficiency, reliabili= >ty, and cost savings, than the DC operation, but people in
the industry have reached this conclusion. AC operation has the drawbac= >k of flicker, fluctuating intensity, which is now
recognized as a health hazard, so it must be reduced/eliminated. Was ju= >st scoping out a small mains powered bulb, and it definitely
exhibited an afterglow of a full 45 seconds after power was removed, no= >t uniform across a bulb population, but close enough. It is
definitely using persistent phosphors. Needless to say one would need a=
any flicker.
Lots of background info here:
https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b00979
Another terrifying health hazard!
It's easy enough to get a photodiode and a scope and see light
waveforms. Do you have an oscilloscope?
I bought a few jugs of various color glow-in-the-dark paints from
Amazon, and pulsed them with a UV LED and scoped the optical
waveforms. They appeared to be zero-delay, zero persistance, to around=
5 ns resolution.
I have seen a small afterglow from fluorescent tubes.
The warm-white LED spot lamp just above my desk here has zero visible
afterglow.
Never sit under an Aspen tree on breezy, sunny days. The light flicker=
will kill you. Avoid all rapid eye movements, ditto sure death.I think my monitor has a LED backlight, it changes brightness all the tim= >e
Campfires flicker and are lethal too.
when working.
Same for my laptop.
But I did switch off the auto brightness feature in the laptop,
annoying changing all the time.
And my room LED lighting is in fact PWM controlled:
https://panteltje.nl/panteltje/pic/ethernet_color_pic/
Some of these high end light fixtures that program intensity and color temp= >erature of the light source are ridiculously expensive.
Some LED lights have no converter chip but run directly from AC,
https://panteltje.nl/pub/LED_light_circuit_diagram_IMG_6925.JPG
the capacitor on the left limits the current
So any current spike will cause a flash.. and kill the LED as in my case.=
So avoid that type.
https://panteltje.nl/pub/LED_light_fix_IMG_6918.JPG
Except for the susceptibility to being destroyed, that looks like a pretty = >good circuit.
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