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Lighting Challenge (or not)
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Please be positive and constructive with your questions and comments.

Lighting Challenge (or not)

by bnewell on Mon Feb 07, 2011 12:39 pm

Hi everyone, I'm new to the forum and electronics in general. So, I NEED your help figuring out how to do a simple lighting project. This is actually for my friend's thesis show. PLEASE READ ON.

YOUR CHALLENGE:
Part of the show is a piece composed of 50 paintings, each 2' x 2', hung in a circle. Each painting is like a video frame. The idea is to light them in sequence, all within one second (so 50 frames per second (and it would be great to make the rate adjustable)), and then go to full on (all lights at once), full off, etc.. I need it to be able to trigger from a motion sensor, run on a loop (as in a different mode), and have a master switch to shut the whole thing down. Let's assume that the lights are 100w bulbs - I'm also open to better lighting ideas, but each light needs enough output to light up 4sq/ft from a foot or two away. Also, it can't have a dedicated computer like a desktop/laptop, but we can tuck away smaller devices.
CAN YOU SOLVE THIS PROBLEM? Great, tell me how!

The arduino seemed like a good starting point, but like I said, I know practically nothing about electronics, so I'm open to any suggestions. I do know electrical basics. Like, I can wire my house. That kind of thing.
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Re: Lighting Challenge (or not)

by adafruit_support_bill on Mon Feb 07, 2011 1:14 pm

Switching a 100 incandescent bulb that fast is likely to be a problem. It will probably take more than 1/50 sec to achieve full brightness. You would need to program some overlap in your sequence - probably not what you want. And the bulb lifetime is likely to be short.

Switching a CFL at that speed is out of the question entirely. That leaves LEDs or xenon strobes. Both of which are capable of achieving the speed you need, but a bit expensive if you need 50 of them. (small LEDs are cheap, but you would need some high powered ones for your application).

Anoter possibility is a mechanical or semi-mechanical solution. Maybe a 500W halogen projector bulb in the center of a rotary shutter with 50 aperatures? A xenon strobe with a rotating mirror?

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Re: Lighting Challenge (or not)

by bnewell on Mon Feb 07, 2011 1:24 pm

CORRECTION
OOPs, my mistake. The rate needs to be half that, 25fps.
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Re: Lighting Challenge (or not)

by bnewell on Mon Feb 07, 2011 1:27 pm

Also, people are standing in the middle of this space, so ideally, it's completely open and the lights will be mounted above each painting on the wall. The strobe idea is interesting, but if a bunch of people are in there, they'll block the light.
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Re: Lighting Challenge (or not)

by zener on Mon Feb 07, 2011 1:38 pm

I am curious about what happens when you switch 60Hz AC incandescent bulbs at 25Hz. You might want to explain what effect you are looking for there. You may get some beat frequency going. And incandescents don't respond that fast.

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Re: Lighting Challenge (or not)

by adafruit_support_bill on Mon Feb 07, 2011 1:40 pm

Can you give us a rough idea of your budget? What you want is possible. But to fit it into an art student's budget (at least as I remember it :wink:) might require some compromise.

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Re: Lighting Challenge (or not)

by bnewell on Mon Feb 07, 2011 3:38 pm

Let's just say, cheapest possible solution, and if cheapest possible is expensive, then it is what it is.
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Re: Lighting Challenge (or not)

by bnewell on Mon Feb 07, 2011 3:48 pm

Thanks for the heads up on the lights: LEDs or Xenon. I suspected that incandescent would not cut it.

Zener, I'm don't want to run the lights at 25Hz AC. I want to light 25 paintings per second, in sequence.

Think of it like a marquee sign, where one bulb lights following another, and then goes out until the sequence comes around again. I would prefer that no two bulbs were lit at the same time, but if there has to be some kind of residual signal, that's OK.
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Re: Lighting Challenge (or not)

by adafruit_support_bill on Mon Feb 07, 2011 5:38 pm

There are these. Relatively inexpensive for a strobe, but you could probably negtotiate a quantity discount for 50. These are fairly easy to trigger. The problem is the recycle time for this one is 3 seconds. You need 2 seconds. (50 frames @ 25/sec)

I don't have any experience with this specific unit, but some similar units will fire at reduced output on a short recycle. 40 watt-seconds at close range should be more than enough for this application - especially if the ambient lighting is not too bright.

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Re: Lighting Challenge (or not)

by henk on Mon Feb 07, 2011 10:35 pm

Wouldn't it be possible to mount the light on a servo that would step through the pictures from 1 to 50 and then flash the light as it steps. That would be cheaper then buying and mount 50 lights. If the timing is to slow you could build two setups one stepping thru the odd numbered painting and one stepping thru the even ones. An Arduino would easily handle the positioning of the servos and the flashing of the lights.
Just a thought.

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Please be positive and constructive with your questions and comments.