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Moreno

An ideal street lightning

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2 hours ago, mistermack said:

Maybe it will end up that they are all controlled by motion detectors, so they only light what's necessary.

I bid on a design like this for an indoor storage facility. The system lights up the hallway 20 feet in front of you and turns the lights off 20 feet behind you as you walk down the hallway to your storage bay. Very efficient for a business where people are coming and going at all times, and should be viable for street lighting as well. The detectors can be set so smaller animals don't set them off. 

 

 

It could be there's a better, more ideal design out there for LED street lighting, since much of the industry had to start out retrofitting existing fixtures and poles with designs that emulated incandescent bulbs. With street lighting, the strategy is still to put the lamps up high and drive the light downwards in a patterned pool, and the broader the area to light, the higher the pole needs to be. But a single LED lamp can have diodes angled in different ways to cast light in ways a bulb can't. The lenses can emit light in a rectangle for streets and parking lots. I think the strategies need to change to match the capabilities of the technology. 

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17 hours ago, StringJunky said:

Is visible blue energetic enough?

Yes,.

I invite you to consider, for example, the workings of a "white LED" where  an LED actually emits blue light and some of this is down converted to the rest of the visible spectrum by some sort of phosphor.

Edited by John Cuthber

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On 11/16/2019 at 7:38 PM, Phi for All said:

I bid on a design like this for an indoor storage facility. The system lights up the hallway 20 feet in front of you and turns the lights off 20 feet behind you as you walk down the hallway to your storage bay. Very efficient for a business where people are coming and going at all times, and should be viable for street lighting as well. The detectors can be set so smaller animals don't set them off. 

The way things are going towards cars broadcasting data, you might not need to rely on motion detection. 

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On 11/16/2019 at 11:56 AM, mistermack said:

Maybe it will end up that they are all controlled by motion detectors, so they only light what's necessary. Or with driverless cars, there will be no need for street lights or headlights. 

What about pedestrians and cyclists?

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1 hour ago, Moreno said:

What about pedestrians and cyclists?

Their smartphones, watches, etc (including, in future, their clothes) will communicate with the vehicles and the road ... and the streetlights 

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Over here, where streetlights are needed 16 hours per day this time of the year, I think that could save quite some energy especially in less crowded areas. One test* of equipment claimed to reduce energy consumption 40-50%. But I don not think increased maintenance costs etc. were discussed in this test.
In context of OP, in these tests there are discussions about the type of light source to use and also about how far ahead (and behind) the light should be at 100%. 

1 hour ago, Strange said:

Their smartphones, watches, etc (including, in future, their clothes) will communicate with the vehicles and the road ... and the streetlights 

Less serous note: Smartphone runs out of battery: No smartphone flashlight and also no streetlights = complete darkness? :-)

 

*) Fact sheet: www.grow-smarter.eu Stockholm pdf

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I think it comes to a question: what is better - daylight/soft white or golden yellow? And how is it possible to remove excessive blue component from LED light? 

Edited by Moreno

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2 hours ago, Moreno said:

I think it comes to a question: what is better - daylight/soft white or golden yellow?

what is better - day or night? is it better if your enemy can see you?

Edited by dimreepr

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4 hours ago, Moreno said:

I think it comes to a question: what is better - daylight/soft white or golden yellow?

Again, better for what purpose? Daylight is better if you want to see true colors. Warm light is more calming. Bright light makes people happier. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897760/

Quote

Subjects reported that they felt happier in brighter conditions and more relaxed in warmer color temperature conditions.

I think the big question is, do you want people driving vehicles to feel more relaxed, or do you want them more alert? I've seen case studies (there should be more formal experiments available) that concluded higher color temperature lighting increases productivity at work, which they associated with higher alertness. I think alertness is also more important to pedestrians than feeling relaxed, but maybe that's just me. 

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The best street lighting is probably the one that gets the local politician re-elected at the lowest cost.

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33 minutes ago, John Cuthber said:

The best street lighting is probably the one that gets the local politician re-elected at the lowest cost.

Then you definitely want high-pressure sodium vapor, or metal halide lamps. The fixtures are everywhere, and the bulbs are cheap, cheap, cheap. Replacement bulbs and electric costs usually come out of different budgets, so the politician can pretend it's the most cost-effective way to go. This is the American way, go cheap on one-time costs and pay through the nose on monthly fees and maintenance. Ten year plans are for socialists.

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On 11/17/2019 at 9:36 AM, John Cuthber said:

Yes,.

I invite you to consider, for example, the workings of a "white LED" where  an LED actually emits blue light and some of this is down converted to the rest of the visible spectrum by some sort of phosphor.

The trouble is 'blue' is next door to uv in the spectrum and some blue LED's can produce uv. What's to say it's not that part of the blue LED's emission range that's causing the phosphors that give white to glow? I've tried looking at emission ranges and some bleed into sub-400nm.

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23 hours ago, StringJunky said:

The trouble is 'blue' is next door to uv in the spectrum and some blue LED's can produce uv. What's to say it's not that part of the blue LED's emission range that's causing the phosphors that give white to glow? I've tried looking at emission ranges and some bleed into sub-400nm.

Newton would disagree, having put indigo and violet in the space between blue and UV.

There's undoubtedly some  light produced below 400nm, but not very much.

And, for what it's worth, 400 nm is visible. The exact "start" of the UV is rather poorly defined.

 

But your implication is that the designers chose a phosphor that only works "by accident".

Not only that, but there is direct evidence that the phosphors absorb  visible (blueish) light.

Have a look at a white LED when it's not running.
It looks yellow.

Do you have some extraordinary evidence?

 

 

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19 hours ago, John Cuthber said:

Newton would disagree, having put indigo and violet in the space between blue and UV.

 

While there is an argument for putting one more color beyond blue, Newton's reason for adding 2 had to do with his religious belief that the number 7 held a special significance. 

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5 hours ago, Janus said:

While there is an argument for putting one more color beyond blue, Newton's reason for adding 2 had to do with his religious belief that the number 7 held a special significance. 

True. (And, personally, I think he should have gone with turquoise or peach as the 7th. Who  seriously thinks indigo isn't blue?)

The important point is that 1 exceeds zero.
So

On 11/19/2019 at 8:11 PM, John Cuthber said:

'blue' is next door to uv

is just plain wrong regardless of Newton's numerology

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3 hours ago, John Cuthber said:

True. (And, personally, I think he should have gone with turquoise or peach as the 7th. Who  seriously thinks indigo isn't blue?)

Roy G BTV and Roy G BPV just don’t have the same ring to them. 

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