LEDs as lamp replacements

There might need to be some amount of filtering done on the input that is not shown on the sample schematic. The chip needs a minimum of 8 VDC input, so to for an AC bulb replacement, you'd need to add a bridge rectifier and probably a small filtering cap.

Well, that's not strictly true. The issue of where the input voltage comes from, is carefully avoided in the data sheet. It only shows that the chip can operate from a DC input range of 8 to 450v. To get the DC input from the mains, would still require a bridge and smoothing cap. However, looks like a useful chip, and a good candidate for the back end processing. It claims that it can drive "hundreds" of LEDs in series / parallel strings. Still reserving judgement at this time ...

Arfa

Here's a really interesting site

Follow the various page links to the chromaticity chart, and " More information on LEDs" at the bottom. I didn't realise that they were already in use in street lighting. There is mention of higher colour temperatures improving human night vision. There is also an interesting LED colour chart, which shows one at 4500K called "incandescent". A couple of years back, I was in Disney when they put on a show in front of the Magic Castle. There was a stage spot set up on the top of a pole, projecting a brilliant white beam of considerable strength. I didn't take much notice of it, until it suddenly changed colour. During the show, it produced a whole range of colours, but I couldn't see that the enclosure was anything like big enough to accommodate a coloured gel wheel. I remember wondering at the time, if this had been implemented using very high power RGB LEDs. I suppose that it is also possible that it could have been a plasma lamp with dichroic mirrors and LCD panels. Are any LEDs actually powerful enough to make stage lighting from ? Can they be mounted in any way that allows light collection and direction through beam forming optics ?

Arfa

LED's are being used for stage lighting, but not in the high power movers or Ellipsoid's (YET). WHat you probably saw was a martin MAC2000 or such at disney. They have full color mixing onboard VIA DMX

THere are some interesting new LED stage lighting also:

BOB

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heavily

if

that

right

See latest development in led lighting here

BOB

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It didn't look quite like that and didn't have remote move capabilities, but was remotely controlled in as much as the colour changing and intensity, so I guess it was on a DMX bus. It was on the top of a pole, so clearly made to work in outdoor conditions, and small and squat, which was made me think that it used technology that I hadn't seen in that application before. I also seem to recall that I was particularly struck by the range and intensity of the colours it produced. Guess I'll never know for sure. The links contained some interesting stuff on high power LED lighting. Seems to me that the LEDs themselves have pretty much evolved to the point of usefulness, and that it now needs more developments in the optical part of the equation, and colour temperature rendition. BTW, did you get the partial schematic for the 'HT70 that I sent you, as requested in your post of a few days ago ?

Arfa

"Arfa Daily" wrote in news:7hzli.8397$ snipped-for-privacy@newsfe4-win.ntli.net:

Hmm. :) Last post after a long day, that was. Should have seen that it needed DC.

No, i did not get it. could you resend it? Email has been funky lateley......

Bob

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OK, it's resent to the same address that you used to post this, but from a different one of my addresses. Attachment is a 434k PDF, which shouldn't be a problem. Let me know that you get it ok. If any issues, just contact me direct on the arfa daily address that I use to post here.

Arfa

So, I take it, you are not willing or able to speculate why humans tend to be repulsed by rotten-smelling food, or why they might feel a sense of threat when hearing a prolonged, deep bass sound? Or why guys tend not to be attracted to overly heavy or, conversely, undernourished women? All these things are just chalked up as arbitrary "preferences?"

Bert

"Albert Manfredi" wrote in news: snipped-for-privacy@news.boeing.com:

Some preferences are better founded than others. It makes no sense to pick arbitrary examples as a way to deal with one specific one.

The lighting requirements for a hobby area are very different from a living room.

I've never noticed a problem reading with tungsten at normal lighting levels. But if I did I'd provide a high colour temperature point source for that rather than have all the lighting cold and uninviting.

At the end of the day it's down to preference. And the fact is most prefer 'warm' lighting in the home.

Got this one. thanks.

Bob

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Lostgallifreyan wrote in news:Xns996F816CDEB0Bzoodlewurdle@140.99.99.130:

Correction, that should read "preference for HIGH colour temperatures".

More likely by mimicking 'end of day' light it continues to relax us in preparation for sleep.

"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:

Do you mean warm colours? Sunsets are rare in many places. Even in those areas that have them they are shortlived, and the last light of the day is high colour temperature. Not even high colour blackbody, but a very blue- biased colour, to extreme, as the short waves are the last to arrive, by scattering, as the night falls.

Why do people need shortwave light to avoid eyestrain?

- Don Klipstein ( snipped-for-privacy@misty.com)

In article , Lostgallifreyan wrote in part:

Can you cite how in human vision, where diffraction limitations are not an issue?

- Don Klipstein ( snipped-for-privacy@misty.com)