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Topic: DIY Ambilight from VGA splitter cable possible? (Read 2 times) previous topic - next topic


I once saw a guy mention the possibility of using photocells, with red, green, and blue filters to evaluate the screen, and then apply the values to the RGB Strips.  Initially I figured the "white bleed" for the lack of a better term on the tv would throw it off too much, if you look at most LCD tvs from even a 60 degree angle, they have a significant saturation loss, so I figured this possibility would be out due to the fact that no one wants photosensors inbetween them and their tv. Now, more and more I want to try it, how awesome would that be? No processing, analog data, easy peasy. Any input? 

On the main topic, i forgot to pick up capacitors this morning, I am going to have a working prototype of the first diagram as soon as I get those damn 1uf Caps.  Side note, any suggestions for good reading on Caps? Cant quite grasp the concept to figure what to do when I need to change a diagram voltage. Increase, decrease, how much, how much is too much? 

If the LEDS color value isnt too "choppy" ill leave it that way and use the double transistor switch for each channel(second diagram), however if its terrible, I may run an averaging code through the arduino, to smooth it out a little bit. Thats why I need to understand the CAPS, I cant run 12v into the Analog Pins on the Arduino, right? How would I reduce that down to a level the arduino could handle? A resistor?

Thanks for all the help, happy to see the project is gaining interest. 

Still a noob but getting there.....


Who doesnt love frying their arduino by applying 12v to the 5v rail.......damnit.......

On the good side!
I got the VGA Ambilight set up!


Disclaimer: I use an All-In-One for my main computer at work, the laptop the VGA is connected to is ARCHAIC and for some reason wont let me mirror the desktop.  The best I can do from work is display the background color on the LED, Screensavers are poo and youtube is soooo slow on this thing its terrible.

Well, need some more funds to replace the arduino..... But I will take this home tonight and see what it looks like running on a good system. I was thinking, maybe if its too choppy I could add capacitors in parallel with the wire running to each base, small ones, to create a slight fade, instead of an abrupt chop chop chop.

Still a noob but getting there.....


Hi there - thanks for sharing the info on this project!

I'm looking to do exactly the same thing and was wondering if you have a schematic of the finished working version. I'm also a newbie & don't recognise some of the components ont he board.

To answer some of the earlier questions about why I need this - I'm in a project called temp0rary ( temp0rary.com ) and we have a live VJ as part of the band. He's running his computer pretty hard with all the clips, so what we need to do is take the VGA signal from the projected visuals, do some *very* rough analysis of the R/G/B values, and then have LED lighting on stage that *sort of* follows what's going on with the visuals (i.e, if visuals are mostly red, the performers light up red too, dark is dark, bright is bright, nothing more than that really...)

Because we already have a lot of kit, and the laptops on stage are already dangerously close to maxed out, it makes more sense to split the VGA, analyse is in a quick & dirty fashion with an Arduino, and use that to squirt out RGB values to control the LEDs.

If anyone has any other info about controlling LED lights like these ones, please let me know!:


Jun 15, 2013, 04:03 am Last Edit: Jun 15, 2013, 04:08 am by desolation Reason: 1
I followed MrWolf1701's schematic to a T, varying a few ohms here or there on resistors due to lack of exact matches on hand.   I never ended up integrating it with the arduino, it actually works pretty damn well by itself.  If you dont want to have other options, if you only want it to be controlled by the VGA signal, an arduino may not be required. If you have any specific questions about that schematic I am more than happy to help out. The project never got completed, I bought a 3d printer and cant get enough of it, nuff said.  The uncompleted project(as you see it in the pictures above) is actually here in my office right behind me.

Still a noob but getting there.....

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