Why are pathetic LEDs still blinding?

My LED bay lights are fairly broad-banded and I don’t have problems with sharp shadows or false colors. What I really like are bright enough lights to be able to see what the heck I’m doing. Eight of them makes 120,000 lumens with lots of diffusion and a.) have a 50,000-hour expected life, and b.) can all be wired to a single 15-amp lighting circuit. Incandescent bulbs providing the same output would require 120 bulbs and 8-10 15-amp circuits. And the color balance of those isn’t anywhere near white. And then there’s the 800-hour lifespan. (One could use traffic signal bulbs—8000 hours and 133 watts—bring you checkbook and hope somebody is still making them.)

I don’t think anyone can complain about color balance for recent LED illumination products if the alternative for them is fluorescent tubes. The color quality of old shop-grade fluorescent tubes is really terrible and difficult to correct. But at least they die young by comparison, are difficult to change on a 14-foot ceiling, and require hazmat procedures (shhhh!) if one falls and shatters. And my experience with fluorescent curlicues is that they make enough heat to fry their electronics. (Cheap screw-in LEDs have the same problem.)

That’s why most shops (and all large interior spaces) prior to LEDs used mercury-vapor (or sodium-vapor) bay lights. Those take 5-8 minutes to reach full illumination and their color balance is also quite narrow, particularly for sodium-vapor lights.

The ceiling fixtures I used in my shop’s upstairs are color-programmable LEDs. Again, 18 fixtures are happy on a single 15-amp circuit and I have them programmed for 3500K—a bit less yellow than incandescent but warmer than daylight. So much better than incandescent or fluorescent ceiling fixtures. I bought two boxes of 10 on Amazon for maybe a coupla hundred.

LED bulbs in shop-light fixtures has been transformative for me. No more burns, and I can reserve my “vocabulary” for other screw-ups.

Rick “not arguing that modern headlights are not glarey, but many are discharge and halogen causing the problem” Denney
 
I illuminate my shop with 1.8kw of LED light, but I followed the IESNA lighting design guide and made my plans and selections carefully. It is wonderful illumination, but don't look up at the 13' ceiling without a shade 12 welding glass. Up until that point, I snobbishly spent the extra on US made fixtures and an excessive amount of TRITEN-50 fluorescent bulbs used for showroom displays. I moved the fancy fluorescents into my basement from my old shop(s), and at this point, I've had it with expensive Advance ballasts and hard to find tubes burning out every other year. The lighting is beautiful, but degrades and requires a lot of maintenance. I just bought a ten-pack of frosted Amazon fixtures at 5000k and 140 watts each. I have low expectations, but after sticking similar fixtures up in my upstairs loft above my shop, I think it might be bearable- we'll see, my basement is my office, I spend as much time in there as I do in bed as it goes.

LED light measurement is not the same as real light. Because they are driven in pulses, that introduces a time constant into the luminous flux. It's no longer intensity to lumens, it's intensity-time to lumens. Same with flux, intensity-area becomes intensity-time-area. Many light level meters will not measure LED correctly unless they use a time constant. It's a simplification, but usually the concepts are simple and the practice brings the nuance.
 
pontiac428 said:
I illuminate my shop with 1.8kw of LED light, but I followed the IESNA lighting design guide and made my plans and selections carefully. It is wonderful illumination, but don't look up at the 13' ceiling without a shade 12 welding glass. Up until that point, I snobbishly spent the extra on US made fixtures and an excessive amount of TRITEN-50 fluorescent bulbs used for showroom displays. I moved the fancy fluorescents into my basement from my old shop(s), and at this point, I've had it with expensive Advance ballasts and hard to find tubes burning out every other year. The lighting is beautiful, but degrades and requires a lot of maintenance. I just bought a ten-pack of frosted Amazon fixtures at 5000k and 140 watts each. I have low expectations, but after sticking similar fixtures up in my upstairs loft above my shop, I think it might be bearable- we'll see, my basement is my office, I spend as much time in there as I do in bed as it goes.

LED light measurement is not the same as real light. Because they are driven in pulses, that introduces a time constant into the luminous flux. It's no longer intensity to lumens, it's intensity-time to lumens. Same with flux, intensity-area becomes intensity-time-area. Many light level meters will not measure LED correctly unless they use a time constant. It's a simplification, but usually the concepts are simple and the practice brings the nuance.
Click to expand...
LED bulbs are not pulsed unless they use a PWM dimmer circuit, and even then the PWM frequency may be high enough to avoid visible flicker. But there are other strategies for dimming that don't use PWM.

My bay lights are not pulsed, and I don't think screw-in bulbs generally are, either. All the OEM power supplies I see are DC-output supplies, either constant voltage or constant current, but not pulsed.

I have tested freeway dynamic-message signs in the factory (which is my field) and used a camera with a long shutter speed, swept across the LED during the exposure, to determine pulsing. Those LEDs often are pulsed to increase their lifespan and reduce power consumption, and also for dimming to match the output to the ambient light levels.

Rick "LEDs are just diodes" Denney
 
rwdenney said:
LED bulbs are not pulsed unless they use a PWM dimmer circuit, and even then the PWM frequency may be high enough to avoid visible flicker. But there are other strategies for dimming that don't use PWM.

My bay lights are not pulsed, and I don't think screw-in bulbs generally are, either. All the OEM power supplies I see are DC-output supplies, either constant voltage or constant current, but not pulsed.

I have tested freeway dynamic-message signs in the factory (which is my field) and used a camera with a long shutter speed, swept across the LED during the exposure, to determine pulsing. Those LEDs often are pulsed to increase their lifespan and reduce power consumption, and also for dimming to match the output to the ambient light levels.

Rick "LEDs are just diodes" Denney
Click to expand...
+1.
 
Many lights are pulsed, and the more they are hyped as high-output, the more overdriven they are in PWM. Some constant current drivers flicker from driver feedback along with fluctuations in input voltage, especially cheap ones, mimicking a 60 cycle flicker. Brake lights are totally PWM driven, that's how they use the same bulb for tail light and for brake light signals. Your Radio Shack breadboard kit LEDs don't flicker, but your bright fixtures and H-O flashlights do.
I don't expect electrical engineers to take my word for it, but here's a touch on the subject.
 
When the bulbs burned out in my wife's garage door opener, I replaced them with Costco screw-in LED bulbs. Then you had to get right up to the door to get the built-in transmitter in the car to work. And sometimes it wouldn't. This only when the bulbs were lit. I exchanged them for rough service incandescent bulbs, and the problem went away.

Is there a way to tell if a LED will put out RF interference?
 
Provincial said:
When the bulbs burned out in my wife's garage door opener, I replaced them with Costco screw-in LED bulbs. Then you had to get right up to the door to get the built-in transmitter in the car to work. And sometimes it wouldn't. This only when the bulbs were lit. I exchanged them for rough service incandescent bulbs, and the problem went away.

Is there a way to tell if a LED will put out RF interference?
Click to expand...
The standard RF detector is an AM radio.

Rick “still may have one of those around” Denney
 
pontiac428 said:
I illuminate my shop with 1.8kw of LED light, but I followed the IESNA lighting design guide and made my plans and selections carefully. It is wonderful illumination, but don't look up at the 13' ceiling without a shade 12 welding glass. Up until that point, I snobbishly spent the extra on US made fixtures and an excessive amount of TRITEN-50 fluorescent bulbs used for showroom displays. I moved the fancy fluorescents into my basement from my old shop(s), and at this point, I've had it with expensive Advance ballasts and hard to find tubes burning out every other year. The lighting is beautiful, but degrades and requires a lot of maintenance. I just bought a ten-pack of frosted Amazon fixtures at 5000k and 140 watts each. I have low expectations, but after sticking similar fixtures up in my upstairs loft above my shop, I think it might be bearable- we'll see, my basement is my office, I spend as much time in there as I do in bed as it goes.

LED light measurement is not the same as real light. Because they are driven in pulses, that introduces a time constant into the luminous flux. It's no longer intensity to lumens, it's intensity-time to lumens. Same with flux, intensity-area becomes intensity-time-area. Many light level meters will not measure LED correctly unless they use a time constant. It's a simplification, but usually the concepts are simple and the practice brings the nuance.
Click to expand...
White LEDs use a combination of a UV LED and phosphors to generate the white-light spectrum. In addition to fluorescence, they exhibit phosphorescence -- their light output doesn't immediately go to zero when the current flow through the LED is zero. This is easy to verify, just turn turn off an LED bulb (after sunset) and you will see what I mean.

That phosphorescence smooths out the light pulses coming out of LED bulbs when they're PWM-driven. It certainly will complicate the procedure to determine the average light intensity. Old-style fluorescents also exhibit phosphorescence.

For this reason, white-light LEDs are not good for applications like strobe lights where you want to "freeze" repetitive motion (like a tire spinning, spindle rotation or as an automotive timing light). The light output decays slowly, blurring the image you see. Single-color LEDs are much better for that sort of application.
 
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