What LED bulb for Blue/Red Dome?

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mega_lumens

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I’m trying to convert an airport runway light into a lamp. The dome is glass Kopp red/blue 4” deep.
What LED bulb would work best to produce most natural looking red-blue colors? I was thinking an A19 style bulb either 2200K or 2700k? Is CRI above 80 important in this application or it gets filtered out? Thank you for the tips..
IMG_1808.jpeg
 
Higher CCTs will have more blue relative to the red compared to low CCTs, and higher CRI lamps will usually have better red output (they usually have red and green phosphors on a blue LED vs. the yellow phosphor on a blue LED of the lower CRI lamps). Given that the dome was originally used on an incandescent source, I'd probably start with a 2700K or 3000K 90+ CRI A19 and see how it looks (and the good news is that those lamps are usually widely available). If I didn't like the red to blue ratio, I'd then either experiment with different CCT lamps, or just get a color-changing lamp and adjust until it looks correct.
 
mega_lumens said:
I’m trying to convert an airport runway light into a lamp. The dome is glass Kopp red/blue 4” deep.
What LED bulb would work best to produce most natural looking red-blue colors? I was thinking an A19 style bulb either 2200K or 2700k? Is CRI above 80 important in this application or it gets filtered out? Thank you for the tips.. View attachment 93986
Click to expand...
Interesting. What does the socket look like inside? Is there room for a standard A19 lamp?
 
PhotonWrangler said:
Interesting. What does the socket look like inside? Is there room for a standard A19 lamp?
Click to expand...
Yes there is room for A19. There is a metal base that houses the socket. It’s similar size to E26 socket. Original bulb is a 6 volt T10P aviation bulb. These lights have their own transformers because runway lights are supplied by 5,000 volt constant current.
 
mega_lumens said:
These lights have their own transformers because runway lights are supplied by 5,000 volt constant current.
Click to expand...
That is fascinating. What is the rationale for feeding all of the runway lights on 5kv DC? Maybe DC to remove a source of possible flickering? But why the high voltage?
 
If it's using a transformer for stepdown, it's not running on DC...

The airport lighting circuits are often a constant current series circuit. This approach is chosen because it results in uniform brightness of all the lamps of a given type, and it inherently compensates for voltage drop (which may be significant over the length of a runway)
 
Go with a higher CRI LED. Regardless of CCT the lower the CRI the more deficient the spectrum is in the red area. I find low CRI LEDs through a red filter look pinkish. As for CCT, you probably want something mid-range to bring out both the red and blue equally. I would go with 4000K to 5000K.
 
This should make a great conversation-starter at parties, especially if it spins.
“Good evening, sir. Do you know why I invited you over?”
 
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