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That's ONE way to make white LEDs. Another, more expensive but much better way, is to use an RGB LED and tune the driver to emit the color you want from the tr

That's ONE way to make white LEDs. Another, more expensive but much better way, is to use an RGB LED and tune the driver to emit the color you want from the triad. They're getting cheap enough now (insanely cheap, in fact) that it is now feasible to fit street lamps with them. Imagine the use that could be had if you could change the color of street lamps on demand. Guide vehicles in an evacuation, direct police to a particular location by coloring a lamp red, or something. Direct ambulance by coloring a lamp blue. I don't know. Seems like it could be useful. It's less about the LED being suitable for street lamps than it is about the lensing chosen to direct the light to the proper locations under the lamp.

jacobolus 8y ago
> more expensive but much better way, is to use an RGB LED This is better for displays (or maybe stage lighting, art projects, fancy effects, ...) but not better for standard room lighting, and definitely not better for street lamps. Using street lamps as information sharing devices makes a cute 1 minute demo, and sounds cool to sci-fi fans, but in practice would be gimmicky and not very effective. The actual light coming out of “RGB” LEDs necessarily has a quite spiky spectrum, because they overemphasize supporting a wide color gamut. They also include more short wavelength light than is desirable for nighttime use (compromising night vision). e.g. https://cdn2.goughlui.com/wp-content/uploads/2015/12/hue-default-spectral.png https://cdn2.goughlui.com/wp-content/uploads/2015/12/hue-def... > It's less about the LED being suitable for street lamps than it is about the lensing chosen to direct the light to the proper locations under the lamp. I’m not quite sure what you are trying to say with this bit. For best lighting, there would be more lamps spaced closer together, placed at lower height, orange in color and individually dim, and diffused and well shielded from the side. These are all features which would be helpful for any type of lamp. Unfortunately, the LED streetlamps adopted by cities are high up, widely spaced, much too blue, extremely intense, and not shielded from the side.

jacobolus 8y ago

> more expensive but much better way, is to use an RGB LED This is better for displays (or maybe stage lighting, art projects, fancy effects, ...) but not better for standard room lighting, and definitely not better for street lamps. Using street lamps as information sharing devices makes a cute 1 minute demo, and sounds cool to sci-fi fans, but in practice would be gimmicky and not very effective. The actual light coming out of “RGB” LEDs necessarily has a quite spiky spectrum, because they overemphasize supporting a wide color gamut. They also include more short wavelength light than is desirable for nighttime use (compromising night vision). e.g. https://cdn2.goughlui.com/wp-content/uploads/2015/12/hue-default-spectral.png https://cdn2.goughlui.com/wp-content/uploads/2015/12/hue-def... > It's less about the LED being suitable for street lamps than it is about the lensing chosen to direct the light to the proper locations under the lamp. I’m not quite sure what you are trying to say with this bit. For best lighting, there would be more lamps spaced closer together, placed at lower height, orange in color and individually dim, and diffused and well shielded from the side. These are all features which would be helpful for any type of lamp. Unfortunately, the LED streetlamps adopted by cities are high up, widely spaced, much too blue, extremely intense, and not shielded from the side.