General Project FadeCandy Neopixels Questions

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Thomaseo1
 
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General Project FadeCandy Neopixels Questions

Post by Thomaseo1 »

Synopsis
I am looking into getting the FadeCandy and Neopixels for a DIY telecine (Film Digitizer) project I'm working on that has a few special requirements.
What I am attempting to do is replace the projectors 100w lamp, (in an area of about 2x2 inches) with an equivalent LED array of RGB (=White) at 1600 total Lumens overall output where levels of each color red, green, and blue can be controlled to fix white balance issues inherent in LEDs in general. The second part is to have the LEDs change their levels from off, 25%, 50%, 100% each at a approximate rate of 1/48 a second or determined by the computer.

FadeCandy Questions
Does using the windows software allow you to send signals from the computer and control the LEDs in real time or is there a lag delay and if so how long?
I have read that FadeCany can output up to 400FPS is this interpolated or actual change rate? if interpolated what is the actual available frame rate?
Can a fade be set to start from 100% total lumens at 0.000 seconds and fade to 25% total lumens at .0208 (1/48) seconds later?
Is dithering permanently on or can it be disabled?
Is there high frequency switching of current to the LED's? or Enough switching to cause potential beat patterns?

NeoPixels Questions
What would be the best choice for Neopixels be to reach the white 1600 lumen value and all pixels LED's fit within 2X2 inches.
What would the recommend power supply be?
Would a heat sink be suggested and if so which ones would also be best to prevent short circuits?

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adafruit_support_mike
 
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Re: General Project FadeCandy Neopixels Questions

Post by adafruit_support_mike »

Thomaseo1 wrote:What would be the best choice for Neopixels be to reach the white 1600 lumen value and all pixels LED's fit within 2X2 inches.
Not gonna happen.

NeoPixels use super-bright LEDs, but that still comes to about 1000mcd each.. maybe 3 lumens max. To get 1600 lumens you'd need more than 500 of them, and it's physically impossible to pack that many into a 2" square.

Thomaseo1
 
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Joined: Thu Jul 24, 2014 9:30 am

Re: General Project FadeCandy Neopixels Questions

Post by Thomaseo1 »

Thanks for your feedback I might not need the full 1600 lumen value, it would be nice to get it up to that amount so I would never need to replace lights to use the projector as a projector. Looking through everything on Neopixels I found the best solution for me might be to make my own with the WS2811 chips and use some super bright Higher Voltage LEDS.

Could someone either point me in the right direction or answer anything, (even a best guess would help) related to my FadeCandy questions.

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adafruit_support_mike
 
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Re: General Project FadeCandy Neopixels Questions

Post by adafruit_support_mike »

I'm afraid that wouldn't work either. The WS28xx series of LED drivers have a built-in limit of about 20mA per LED. The kind of LEDs you'll need will want at least ten times that: https://www.adafruit.com/products/518

Given the FadeCandy's link to the WS28xx family, you probably won't be able to make it work without some serious engineering.

Stepping back for a minute and looking at your general goal, you want to tune the color temperature and balance of a generally white light source. For that, it would probably be easiest to use a field of cool white LEDs (too much blue) and a group of red and green LEDs to adjust the color.

With that kind of setup you can run the cool whites at DC to provide the bulk illumination, and control the red/green LEDs to tune the color temperature. The red and green groups won't need to provide a full 1600 lumens, just enough to counteract the excess blue from the cool whites. 100-200 lumens each should probably be enough.

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