On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote:> On 1/19/2023 5:20 PM, Ricky wrote: > > On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote: > >> On 12/27/2022 11:39 AM, John Larkin wrote: > >>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown > >>> <'''newspam'''@nonad.co.uk> wrote: > >>> > >>>> On 26/12/2022 17:16, Ricky wrote: > >>>>> I know it costs more to make a more efficient LED bulb for room > >>>>> lighting. Is there also a tradeoff between efficiency and operating > >>>>> life? I can't think of a mechanism, but I'm not so familiar with LED > >>>>> light bulb design. > >>>> > >>>> If you push the blue light flux and/or residual heating high enough it > >>>> can damage/darken the phosphor used to generate the yellow light. > >>>> > >>>> The surface brightness of recent LEDs is now about the same per unit > >>>> area as the sun - which makes it a bad idea to look directly at them. > >>>> Blue, violet or UV ones especially. > >>> > >>> I have a 12-volt, roughly 1 cm square, array that looks like a welding > >>> torch. It's the kind used in street lamps. > >>> > >>> Why don't they diffuse LED street lamps? They are annoying. > >>> > >> Especially when they start blinking > > > > I can't stand the fast blinking LED tail lights on cars. Everytime I move my line of view, they create a dozen spots of light. When there are more than one it gets insane looking. Seems like most people don't even see this. The first time it happened to me I was trying to merge where there was no merge lane and the ramp was coming from an angle, rather than merging while driving parallel, so the rear view mirror didn't show anything useful. A quick look over my shoulder showed one car passing me, just as I needed to either go or stop. As I turned my head back, the tail lights (those tall Cadillac tail lights) suddenly blossomed into a dozen pairs of lights and I thought it was a bunch of cars! I had to hit my brakes to avoid an accident, only to find there was only the one car. Insane that they would create this sort of hazard, even if everyone doesn't see it. It's the sort of thing that would be changed on an airliner, after the first accident it causes. > > > > I've never found out how rapid the blinking is. > > > I usually see those flashing brake light mods on street racer-type cars > around Providence RI, kids put them on their old Eclipse etc. to make > them look cool. I don't know that they're much improvement over a > regular high-level lamp at avoiding being rear-ended, though.We aren't talking about the same thing. I'm talking about tail/brake lights where the brightness is adjusted by PWM. It saves a few cents by leaving off the inductor too smooth the waveform into a level. -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
LED Bulb Efficiency vs. Operating Life
Started by ●December 26, 2022
Reply by ●January 19, 20232023-01-19
Reply by ●January 20, 20232023-01-20
On 20/01/2023 00:58, Ricky wrote:> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote: >> On 1/19/2023 5:20 PM, Ricky wrote: >>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote: >>>> On 12/27/2022 11:39 AM, John Larkin wrote: >>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown >>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>> >>>>>> On 26/12/2022 17:16, Ricky wrote: >>>>>>> I know it costs more to make a more efficient LED bulb >>>>>>> for room lighting. Is there also a tradeoff between >>>>>>> efficiency and operating life? I can't think of a >>>>>>> mechanism, but I'm not so familiar with LED light bulb >>>>>>> design. >>>>>> >>>>>> If you push the blue light flux and/or residual heating >>>>>> high enough it can damage/darken the phosphor used to >>>>>> generate the yellow light. >>>>>> >>>>>> The surface brightness of recent LEDs is now about the same >>>>>> per unit area as the sun - which makes it a bad idea to >>>>>> look directly at them. Blue, violet or UV ones especially. >>>>> >>>>> I have a 12-volt, roughly 1 cm square, array that looks like >>>>> a welding torch. It's the kind used in street lamps. >>>>> >>>>> Why don't they diffuse LED street lamps? They are annoying. >>>>> >>>> Especially when they start blinking >>> >>> I can't stand the fast blinking LED tail lights on cars. >>> Everytime I move my line of view, they create a dozen spots of >>> light. When there are more than one it gets insane looking. Seems >>> like most people don't even see this. The first time it happened >>> to me I was trying to merge where there was no merge lane and the >>> ramp was coming from an angle, rather than merging while driving >>> parallel, so the rear view mirror didn't show anything useful. A >>> quick look over my shoulder showed one car passing me, just as I >>> needed to either go or stop. As I turned my head back, the tail >>> lights (those tall Cadillac tail lights) suddenly blossomed into >>> a dozen pairs of lights and I thought it was a bunch of cars! I >>> had to hit my brakes to avoid an accident, only to find there was >>> only the one car. Insane that they would create this sort of >>> hazard, even if everyone doesn't see it. It's the sort of thing >>> that would be changed on an airliner, after the first accident it >>> causes. >>> >>> I've never found out how rapid the blinking is. >>> >> I usually see those flashing brake light mods on street racer-type >> cars around Providence RI, kids put them on their old Eclipse etc. >> to make them look cool. I don't know that they're much improvement >> over a regular high-level lamp at avoiding being rear-ended, >> though. > > We aren't talking about the same thing. I'm talking about tail/brake > lights where the brightness is adjusted by PWM. It saves a few cents > by leaving off the inductor too smooth the waveform into a level.The problem is that they PWM pulse them at a frequency that some people can see in their peripheral vision (which is much more flicker sensitive). I guess the engineers who designed it didn't think about their choice of frequency too hard. Anything above about 300HZ frequency would look pretty much continuous but there seem to be several car makers (and street furniture makers that use ~100Hz at a guess). People who see this as a problem are the same ones who don't get on with walls full of TVs or large screen monitors at 60Hz refresh rates. -- Regards, Martin Brown
Reply by ●January 20, 20232023-01-20
On Friday, January 20, 2023 at 4:03:46 AM UTC-5, Martin Brown wrote:> On 20/01/2023 00:58, Ricky wrote: > > On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote: > >> On 1/19/2023 5:20 PM, Ricky wrote: > >>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote: > >>>> On 12/27/2022 11:39 AM, John Larkin wrote: > >>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown > >>>>> <'''newspam'''@nonad.co.uk> wrote: > >>>>> > >>>>>> On 26/12/2022 17:16, Ricky wrote: > >>>>>>> I know it costs more to make a more efficient LED bulb > >>>>>>> for room lighting. Is there also a tradeoff between > >>>>>>> efficiency and operating life? I can't think of a > >>>>>>> mechanism, but I'm not so familiar with LED light bulb > >>>>>>> design. > >>>>>> > >>>>>> If you push the blue light flux and/or residual heating > >>>>>> high enough it can damage/darken the phosphor used to > >>>>>> generate the yellow light. > >>>>>> > >>>>>> The surface brightness of recent LEDs is now about the same > >>>>>> per unit area as the sun - which makes it a bad idea to > >>>>>> look directly at them. Blue, violet or UV ones especially. > >>>>> > >>>>> I have a 12-volt, roughly 1 cm square, array that looks like > >>>>> a welding torch. It's the kind used in street lamps. > >>>>> > >>>>> Why don't they diffuse LED street lamps? They are annoying. > >>>>> > >>>> Especially when they start blinking > >>> > >>> I can't stand the fast blinking LED tail lights on cars. > >>> Everytime I move my line of view, they create a dozen spots of > >>> light. When there are more than one it gets insane looking. Seems > >>> like most people don't even see this. The first time it happened > >>> to me I was trying to merge where there was no merge lane and the > >>> ramp was coming from an angle, rather than merging while driving > >>> parallel, so the rear view mirror didn't show anything useful. A > >>> quick look over my shoulder showed one car passing me, just as I > >>> needed to either go or stop. As I turned my head back, the tail > >>> lights (those tall Cadillac tail lights) suddenly blossomed into > >>> a dozen pairs of lights and I thought it was a bunch of cars! I > >>> had to hit my brakes to avoid an accident, only to find there was > >>> only the one car. Insane that they would create this sort of > >>> hazard, even if everyone doesn't see it. It's the sort of thing > >>> that would be changed on an airliner, after the first accident it > >>> causes. > >>> > >>> I've never found out how rapid the blinking is. > >>> > >> I usually see those flashing brake light mods on street racer-type > >> cars around Providence RI, kids put them on their old Eclipse etc. > >> to make them look cool. I don't know that they're much improvement > >> over a regular high-level lamp at avoiding being rear-ended, > >> though. > > > > We aren't talking about the same thing. I'm talking about tail/brake > > lights where the brightness is adjusted by PWM. It saves a few cents > > by leaving off the inductor too smooth the waveform into a level. > The problem is that they PWM pulse them at a frequency that some people > can see in their peripheral vision (which is much more flicker > sensitive). I guess the engineers who designed it didn't think about > their choice of frequency too hard. Anything above about 300HZ frequency > would look pretty much continuous but there seem to be several car > makers (and street furniture makers that use ~100Hz at a guess). > > People who see this as a problem are the same ones who don't get on with > walls full of TVs or large screen monitors at 60Hz refresh rates.I think we are talking about different things. I don't "see" the flickering. I see the resulting pattern of images when my view changes, like the sign sticks you wave in the air to display text. I find it disturbing because when I'm driving, my spidey sense is always watching the lights of other cars. When I move my eyes and the field of tail lights explodes from two or three cars, to a dozen, it is very disturbing. This has nothing to do with peripheral vision "seeing" the flicker. They need to speed up the rate of flashing, so that this is not visible. It's interesting that not all cars do this. I first saw the flashing in a Cadillac some 20 years ago, or more. So, even today, either not all cars have LED taillights, or some car makers design them to not blink, or blink very fast so it is not observable. The difference in circuitry is very slight. Essentially it requires an inductor and capacitor and maybe a diode, to smooth the current rather than just blinking the LEDs. Or with two strings of LED, it requires two control circuits to set the brightness of each string. -- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Reply by ●January 20, 20232023-01-20
On 20/01/2023 09:18, Ricky wrote:> On Friday, January 20, 2023 at 4:03:46 AM UTC-5, Martin Brown wrote: >> On 20/01/2023 00:58, Ricky wrote: >>> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote: >>>> On 1/19/2023 5:20 PM, Ricky wrote: >>>>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex >>>>> wrote: >>>>>> On 12/27/2022 11:39 AM, John Larkin wrote: >>>>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown >>>>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>>>> >>>>>>>> On 26/12/2022 17:16, Ricky wrote: >>>>>>>>> I know it costs more to make a more efficient LED >>>>>>>>> bulb for room lighting. Is there also a tradeoff >>>>>>>>> between efficiency and operating life? I can't think >>>>>>>>> of a mechanism, but I'm not so familiar with LED >>>>>>>>> light bulb design. >>>>>>>> >>>>>>>> If you push the blue light flux and/or residual >>>>>>>> heating high enough it can damage/darken the phosphor >>>>>>>> used to generate the yellow light. >>>>>>>> >>>>>>>> The surface brightness of recent LEDs is now about the >>>>>>>> same per unit area as the sun - which makes it a bad >>>>>>>> idea to look directly at them. Blue, violet or UV ones >>>>>>>> especially. >>>>>>> >>>>>>> I have a 12-volt, roughly 1 cm square, array that looks >>>>>>> like a welding torch. It's the kind used in street >>>>>>> lamps. >>>>>>> >>>>>>> Why don't they diffuse LED street lamps? They are >>>>>>> annoying. >>>>>>> >>>>>> Especially when they start blinking >>>>> >>>>> I can't stand the fast blinking LED tail lights on cars. >>>>> Everytime I move my line of view, they create a dozen spots >>>>> of light. When there are more than one it gets insane >>>>> looking. Seems like most people don't even see this. The >>>>> first time it happened to me I was trying to merge where >>>>> there was no merge lane and the ramp was coming from an >>>>> angle, rather than merging while driving parallel, so the >>>>> rear view mirror didn't show anything useful. A quick look >>>>> over my shoulder showed one car passing me, just as I needed >>>>> to either go or stop. As I turned my head back, the tail >>>>> lights (those tall Cadillac tail lights) suddenly blossomed >>>>> into a dozen pairs of lights and I thought it was a bunch of >>>>> cars! I had to hit my brakes to avoid an accident, only to >>>>> find there was only the one car. Insane that they would >>>>> create this sort of hazard, even if everyone doesn't see it. >>>>> It's the sort of thing that would be changed on an airliner, >>>>> after the first accident it causes. >>>>> >>>>> I've never found out how rapid the blinking is. >>>>> >>>> I usually see those flashing brake light mods on street >>>> racer-type cars around Providence RI, kids put them on their >>>> old Eclipse etc. to make them look cool. I don't know that >>>> they're much improvement over a regular high-level lamp at >>>> avoiding being rear-ended, though. >>> >>> We aren't talking about the same thing. I'm talking about >>> tail/brake lights where the brightness is adjusted by PWM. It >>> saves a few cents by leaving off the inductor too smooth the >>> waveform into a level. >> The problem is that they PWM pulse them at a frequency that some >> people can see in their peripheral vision (which is much more >> flicker sensitive). I guess the engineers who designed it didn't >> think about their choice of frequency too hard. Anything above >> about 300HZ frequency would look pretty much continuous but there >> seem to be several car makers (and street furniture makers that use >> ~100Hz at a guess). >> >> People who see this as a problem are the same ones who don't get on >> with walls full of TVs or large screen monitors at 60Hz refresh >> rates. > > I think we are talking about different things. I don't "see" the > flickering. I see the resulting pattern of images when my view > changes, like the sign sticks you wave in the air to display text. I > find it disturbing because when I'm driving, my spidey sense is > always watching the lights of other cars. When I move my eyes and > the field of tail lights explodes from two or three cars, to a dozen, > it is very disturbing. This has nothing to do with peripheral vision > "seeing" the flicker.It has everything to do with peripheral vision seeing the flicker. That is why the LED light motif breaks up into several strobe flash images. If the frequency was about 3 or 4x higher then they would overlap. FWIW I do see some of them flicker in my peripheral vision and with those slower ones the flash images are further apart. It is the eye cadence movements that make them so prominent after dark.> > They need to speed up the rate of flashing, so that this is not > visible. It's interesting that not all cars do this. I first saw > the flashing in a Cadillac some 20 years ago, or more. So, even > today, either not all cars have LED taillights, or some car makers > design them to not blink, or blink very fast so it is not observable.I agree - increase the frequency and it would smear them out and look much more like a continuous light source. They can be very distracting. It seems unlikely to me that they had leds bright enough for automotive indicators 20 years ago. The breakthrough in high efficiency LEDs was later than that. The first ones I can recall seeing used in anger were on motorway service vehicles for the "please don't hit me" yellow warning lights. They had sophisticated optics in front of the emitter which made them very strongly collimated beams that were bright from a great distance but never dazzling when you got close to them.> The difference in circuitry is very slight. Essentially it requires > an inductor and capacitor and maybe a diode, to smooth the current > rather than just blinking the LEDs. Or with two strings of LED, it > requires two control circuits to set the brightness of each string.It would be good enough to just up the frequency by a factor of 5x - it isn't like they are even close to losing efficiency by switching losses at what are essentially audio frequencies. I guess they don't see it as a problem since plenty of automakers have exactly the same fault. -- Regards, Martin Brown
Reply by ●January 20, 20232023-01-20
On 20/01/2023 09:51, Martin Brown wrote: <snip>> > It has everything to do with peripheral vision seeing the flicker. That > is why the LED light motif breaks up into several strobe flash images.What Ricky's talking about is when you sweep your eyes eg left to right and see a line of red dots, rather than a smudged single line as you would with an incandescent lamp. Particularly noticeable in the dark of course. Many years ago I diagnosed a faulty instrument without looking inside because I noticed the power-on LED was showing this effect and it was supposed to run from a DC rail supplied from the mains via transformer, rectifier and reservoir capacitor. The capacitor had become disconnected. The service engineer was mightily impressed - "Clive can see 100Hz!" -- Cheers Clive
Reply by ●January 20, 20232023-01-20
On a sunny day (Fri, 20 Jan 2023 10:25:32 +0000) it happened Clive Arthur <clive@nowaytoday.co.uk> wrote in <tqdq6s$20t98$1@dont-email.me>:>On 20/01/2023 09:51, Martin Brown wrote: > ><snip> >> >> It has everything to do with peripheral vision seeing the flicker. That >> is why the LED light motif breaks up into several strobe flash images. > >What Ricky's talking about is when you sweep your eyes eg left to right >and see a line of red dots, rather than a smudged single line as you >would with an incandescent lamp. Particularly noticeable in the dark of >course. > >Many years ago I diagnosed a faulty instrument without looking inside >because I noticed the power-on LED was showing this effect and it was >supposed to run from a DC rail supplied from the mains via transformer, >rectifier and reservoir capacitor. The capacitor had become >disconnected. The service engineer was mightily impressed - "Clive can >see 100Hz!"I have used the effect many times to its advantage: http://panteltje.com/panteltje/pic/sign_pic/ and here: http://panteltje.com/panteltje/quadcopter/hsign.html The eye and both a camera with sufficient long exposure seem to be able to see the dots. my Sony superhad video smeared it out though (second link) They should really run the lights with DC. My cheap satellite receiver 7 segment channel indicator has the same problem if I move my view fast. Indeed one day something will go wrong and you get legislation to fix this.. Long time ago I proposed here something like the first link on the side of your car for advertising...
Reply by ●January 20, 20232023-01-20
On Friday, January 20, 2023 at 4:52:14 AM UTC-5, Martin Brown wrote:> On 20/01/2023 09:18, Ricky wrote: > > On Friday, January 20, 2023 at 4:03:46 AM UTC-5, Martin Brown wrote: > >> On 20/01/2023 00:58, Ricky wrote: > >>> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote: > >>>> On 1/19/2023 5:20 PM, Ricky wrote: > >>>>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex > >>>>> wrote: > >>>>>> On 12/27/2022 11:39 AM, John Larkin wrote: > >>>>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown > >>>>>>> <'''newspam'''@nonad.co.uk> wrote: > >>>>>>> > >>>>>>>> On 26/12/2022 17:16, Ricky wrote: > >>>>>>>>> I know it costs more to make a more efficient LED > >>>>>>>>> bulb for room lighting. Is there also a tradeoff > >>>>>>>>> between efficiency and operating life? I can't think > >>>>>>>>> of a mechanism, but I'm not so familiar with LED > >>>>>>>>> light bulb design. > >>>>>>>> > >>>>>>>> If you push the blue light flux and/or residual > >>>>>>>> heating high enough it can damage/darken the phosphor > >>>>>>>> used to generate the yellow light. > >>>>>>>> > >>>>>>>> The surface brightness of recent LEDs is now about the > >>>>>>>> same per unit area as the sun - which makes it a bad > >>>>>>>> idea to look directly at them. Blue, violet or UV ones > >>>>>>>> especially. > >>>>>>> > >>>>>>> I have a 12-volt, roughly 1 cm square, array that looks > >>>>>>> like a welding torch. It's the kind used in street > >>>>>>> lamps. > >>>>>>> > >>>>>>> Why don't they diffuse LED street lamps? They are > >>>>>>> annoying. > >>>>>>> > >>>>>> Especially when they start blinking > >>>>> > >>>>> I can't stand the fast blinking LED tail lights on cars. > >>>>> Everytime I move my line of view, they create a dozen spots > >>>>> of light. When there are more than one it gets insane > >>>>> looking. Seems like most people don't even see this. The > >>>>> first time it happened to me I was trying to merge where > >>>>> there was no merge lane and the ramp was coming from an > >>>>> angle, rather than merging while driving parallel, so the > >>>>> rear view mirror didn't show anything useful. A quick look > >>>>> over my shoulder showed one car passing me, just as I needed > >>>>> to either go or stop. As I turned my head back, the tail > >>>>> lights (those tall Cadillac tail lights) suddenly blossomed > >>>>> into a dozen pairs of lights and I thought it was a bunch of > >>>>> cars! I had to hit my brakes to avoid an accident, only to > >>>>> find there was only the one car. Insane that they would > >>>>> create this sort of hazard, even if everyone doesn't see it. > >>>>> It's the sort of thing that would be changed on an airliner, > >>>>> after the first accident it causes. > >>>>> > >>>>> I've never found out how rapid the blinking is. > >>>>> > >>>> I usually see those flashing brake light mods on street > >>>> racer-type cars around Providence RI, kids put them on their > >>>> old Eclipse etc. to make them look cool. I don't know that > >>>> they're much improvement over a regular high-level lamp at > >>>> avoiding being rear-ended, though. > >>> > >>> We aren't talking about the same thing. I'm talking about > >>> tail/brake lights where the brightness is adjusted by PWM. It > >>> saves a few cents by leaving off the inductor too smooth the > >>> waveform into a level. > >> The problem is that they PWM pulse them at a frequency that some > >> people can see in their peripheral vision (which is much more > >> flicker sensitive). I guess the engineers who designed it didn't > >> think about their choice of frequency too hard. Anything above > >> about 300HZ frequency would look pretty much continuous but there > >> seem to be several car makers (and street furniture makers that use > >> ~100Hz at a guess). > >> > >> People who see this as a problem are the same ones who don't get on > >> with walls full of TVs or large screen monitors at 60Hz refresh > >> rates. > > > > I think we are talking about different things. I don't "see" the > > flickering. I see the resulting pattern of images when my view > > changes, like the sign sticks you wave in the air to display text. I > > find it disturbing because when I'm driving, my spidey sense is > > always watching the lights of other cars. When I move my eyes and > > the field of tail lights explodes from two or three cars, to a dozen, > > it is very disturbing. This has nothing to do with peripheral vision > > "seeing" the flicker. > It has everything to do with peripheral vision seeing the flicker. That > is why the LED light motif breaks up into several strobe flash images.Sometimes I think you literally can't understand the written word. I am the guy experiencing the issue, yet you are telling me what I saw. It was looking straight at the object and moving my eyes a small amount. Any amount of movement creates the separate images of the flickering light. This is not a matter of peripheral vision.> If the frequency was about 3 or 4x higher then they would overlap. FWIW > I do see some of them flicker in my peripheral vision and with those > slower ones the flash images are further apart. It is the eye cadence > movements that make them so prominent after dark. > > > > They need to speed up the rate of flashing, so that this is not > > visible. It's interesting that not all cars do this. I first saw > > the flashing in a Cadillac some 20 years ago, or more. So, even > > today, either not all cars have LED taillights, or some car makers > > design them to not blink, or blink very fast so it is not observable. > I agree - increase the frequency and it would smear them out and look > much more like a continuous light source. They can be very distracting. > > It seems unlikely to me that they had leds bright enough for automotive > indicators 20 years ago.Talk to Cadillac. You are aware that a tail light is only red, and you can use a large number of LEDs, no?> The breakthrough in high efficiency LEDs was > later than that. The first ones I can recall seeing used in anger were > on motorway service vehicles for the "please don't hit me" yellow > warning lights. They had sophisticated optics in front of the emitter > which made them very strongly collimated beams that were bright from a > great distance but never dazzling when you got close to them. > > The difference in circuitry is very slight. Essentially it requires > > an inductor and capacitor and maybe a diode, to smooth the current > > rather than just blinking the LEDs. Or with two strings of LED, it > > requires two control circuits to set the brightness of each string. > It would be good enough to just up the frequency by a factor of 5x - it > isn't like they are even close to losing efficiency by switching losses > at what are essentially audio frequencies. I guess they don't see it as > a problem since plenty of automakers have exactly the same fault.If you say so. -- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Reply by ●January 20, 20232023-01-20
On 20/01/2023 10:49, panteltje wrote: <snip>> I have used the effect many times to its advantage: > http://panteltje.com/panteltje/pic/sign_pic/ > > and here: > http://panteltje.com/panteltje/quadcopter/hsign.html > > The eye and both a camera with sufficient long exposure seem to be able to see the dots. > my Sony superhad video smeared it out though (second link) > They should really run the lights with DC. >I made one of those, also on Veroboard, though mine had 16 red LEDs. I had the idea of mounting it on a rear windscreen wiper to send polite and friendly messages to the car behind. Then I got a proper job. -- Cheers Clive
Reply by ●January 20, 20232023-01-20
On 2022-12-26 19:49, Sjouke Burry wrote:> On 26.12.22 18:16, Ricky wrote: >> I know it costs more to make a more efficient LED bulb for room >> lighting. Is there also a tradeoff between efficiency and operating >> life? I can't think of a mechanism, but I'm not so familiar with LED >> light bulb design. >> > Lots of light, high chip temp, shorter chip life.I assume that high efficiency means more light for less watts. -- Cheers, Carlos.
Reply by ●January 20, 20232023-01-20
On a sunny day (Fri, 20 Jan 2023 12:27:54 +0000) it happened Clive Arthur <clive@nowaytoday.co.uk> wrote in <tqe1cb$22781$1@dont-email.me>:>On 20/01/2023 10:49, panteltje wrote: > ><snip> > >> I have used the effect many times to its advantage: >> http://panteltje.com/panteltje/pic/sign_pic/ >> >> and here: >> http://panteltje.com/panteltje/quadcopter/hsign.html >> >> The eye and both a camera with sufficient long exposure seem to be able to see the dots. >> my Sony superhad video smeared it out though (second link) >> They should really run the lights with DC. >> > >I made one of those, also on Veroboard, though mine had 16 red LEDs. I >had the idea of mounting it on a rear windscreen wiper to send polite >and friendly messages to the car behind. Then I got a proper job.You could use these in the rear window: http://panteltje.com/panteltje/raspberry_pi_FDS132_matrix_display_driver/index.html
