A couple LED questions

Yes to both. I assume you're looking at LEDs as the pixels in a video display?

Bob M.

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Sorry... that should have been 4,320 times per second....

Actually, both of your questions have much more to do with the driver of the LED than the LED itself.

A little insight into what you're trying to achieve would be a great help here.

Bob M.

typicallt much faster than that, up past 100000 times per second is the norm.

that one should be capable if driven carefully, see if you can get a copy of makers the data sheet. I can't immagine how they could limit one to 256 colours cheaply so they probably don't.

1. Yes, it can change colors 1000 times a second, the question is can your eyes detect more than 30 colors per second?
2. The one you're looking at with an 8 bit PWM signal for each chip can do

256 levels of brightness for each color in the mix. 20% blue, 20% green, 40% red or 10% Blue, 10% Green 20% Red will be the same shade of pink at 2 different brightnesses.

1. =A0Can a multi-colored LED (like the one here -

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Sorry about the delay in answering. I'm using Google Groups and didn't get notice of replies.

What I want to do is this.

Create a pole with 1080 LED's on it and place this pole on a turn- table rotating 30 revolutions per second with a computer changing the color of the LED's when they reach a certain position, creating the illusion of a very large LED screen.

Is this feasible?

Certainly. It's been done. I don't remember the department store I saw it in, but they'd done just this as an advert for perfume or some such (the medium was far more interesting than the message).

an your

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Thank!

I saw an ad for a small ball that displayed a few hundred pixels at most. Not even close to what I'm thinking about.

I'm thinking I'll run into a couple problems with my idea

1. Would my pole be capable of spinning 30 revolutions per second, without being ripped apart by air turbulance?
2. The LED's would be changing colors 11,520 times per revolution, or

345,600 times per second. Is this possible? Would this create an illusion of a solid image?

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aircraft engine rotors manage to hang together at faster rotation rates. (so yes it's possible although it may be challenging)

yes,

at only 30 hz it would flicker horribly.

maybe do two arms 180 degrees opposed?

in the dark it would appear solid, when lit externally it woiuld appear spectral.

As was already noted, this has been done in a commercial product; not at 1080 lines (given the size of discrete LEDs or even the three-colors- in-one-package sort, that will be a BIG display), but it's certainly feasible. You haven't even hit on the most serious problem to overcome, though - how are you going to drive all of those LEDs rapidly enough, and through some sort of drive connection that still lets the thing spin at the necessary rate? It's doable, but best of luck with that - it's not the sort of thing I would expect to be tackled in a hobbyist-type project. And don't forget, you're going to need something to convert conventional- scan 1080p video into the format required by the LED display, while keeping everything nicely synchronized.

Bob M.

Can a multi-colored LED (like the one here -

You can even make it 3 Dimensional that way.

Welllllll....no. Not easily, anyway.

Bob M.