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31  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: May 04, 2012, 12:57:01 am
I was referring to buffer the signal lines since they are getting split to 6 tlc's, not the outputs.
32  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: May 03, 2012, 05:34:09 pm
I guess that was a general question about buffer chips as i'm not sure what to order.
33  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: May 03, 2012, 09:07:23 am
Well I soldered everything together and it all worked. I tried to do some color blending but noticed some of the led were not getting full brightness as they should so I re-soldered the anodes to the 12v rail instead of the 5v and they are at full brightness now which is good but it goes back to shifting as my previous problem. I want to add buffers to the signal lines but not sure what to buy or how to hook them up.

Do I hookup the signal line to the buffer chip and then connect the 6 tlc signal lines to that  single output  (I'm guessing this is the way), or does the signal line split to 6 buffer chips, one for each tlc? Or is there a buffer chip that has a single input to many  buffered outputs?

I have a decoupling capacitors on each tlc, I think they are .1nano (say 104 on them). Should I add some larger ones as well to each board? I'm thinking with the higher current it may be outputting more noise than the small caps can filter.

34  Using Arduino / Project Guidance / Re: fiber optic balloons on: April 20, 2012, 06:11:14 am
If you get the baloon to lift the fiber, you need some kind of diffuser for the tiny little dot of light coming out of the fiber

Good point, this might be an issue, it might not.

I'm going to start small and scale up. I have these 3watt rgb leds hooked up to a constant current source circuit that is connected to a tlc5940 > arduino that I have been using but not sure what the best way to couple it. Right now I have pen shaft glued to the led to channel in side emitting fiber optic but i'm not sure how it will work with the smaller diameter jacketed fiber.
35  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: April 18, 2012, 03:17:28 am
Ok, thats what I was kinda thinking. I'm going to test the boards indiviually and then rebuild it all but this time soldering all the wires in the permanent box i'm building for it.
36  Using Arduino / Project Guidance / Re: fiber optic balloons on: April 17, 2012, 06:41:08 am
Well lasers at a balloon be cool but it would be an uber challange to track a bunch of balloons with even the slightest amount of wind. I guess what I'm looking for is the right type of fiber optic and coupling method with a high powered led in which I can control with an arduino. Possibly just regular ol' single jacketed network fiber optic. I'll just have to experiment with different types of balloons and fiber optic cables.
37  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: April 17, 2012, 03:16:39 am
So i'm just diving back into this and doing some simple code to test things but something is very weird. The regular knight rider code works fine but when I'm just trying to turn a set of leds on it seems to shift out and makes it look funky.

Here is the video

#include "Tlc5940.h"
int green = 32;
 int blue = 0;
 int red = 64;

 void setup()


void loop()
      Tlc.set(red + 0, 4095);
       Tlc.set(red + 1, 4095);
        Tlc.set(red + 2, 4095);
      Tlc.set(green + 0, 4095);
       Tlc.set(green + 1, 4095);
        Tlc.set(green + 2, 4095);

This should just make the first three leds yellow which it does but it shouldn't change like it does. Any clues? Maybe I"m missing something simple.
38  Using Arduino / Project Guidance / Re: fiber optic balloons on: April 10, 2012, 05:14:14 am
I had planned on using larger balloons depending on the needed lift. Maybe a specially made balloon is required i'm not sure, but I'm sure it can be done.
39  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: April 10, 2012, 05:03:24 am
Unfortunately I do not have an oscilloscope at my disposal at this time smiley-sad

I made the measure of ~200k between power and ground pins when the chip is completely out of circuit. I'm going to buy some heatsinks for the tlc to combat the issue but I don't think it will be too big of problem since I will only run the rainbow code a fraction of the time. I should have a video of the fiber hooked up within a week or two.
40  Using Arduino / Project Guidance / fiber optic balloons on: April 10, 2012, 04:49:33 am
Alright so I had an idea of having white balloons floating in the sky with a rgb led in it to make it change colors. Depending on the height of the balloon I can foresee IR losses cropping up. So instead of putting the led in the balloon I was thinking on running fiber optic up to it.

Does anyone have recommendations on what type of fiber to use and what would be the best way to drive it? I want to have multiple lengths from 20ft to 500ft. Could I just use single mode jacketed fiber with an led shining on one end?

Thanks in advance!

41  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: April 06, 2012, 04:50:35 am
I used the power supply from a computer and everything works great. I was even able to ramp it up to the rainbow code that uses the maximum amount of power that I will be using for hour and a half without problems.

One weird thing, some of the tlc chips get really hot while others stay cool even with the same code pumping through them. I noted that the ones that stay cool actually have internal resistance of about 200k between power and ground pins while the others stay open as I would assume it to be.
42  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: March 23, 2012, 04:36:29 pm
Here is a circuit for one of the boards and pic of a pre-hookup of the arduino. Yeah I had a feeling seperate power supplies might be a problem so I was thinking on setting up a 5v to 12v circuit for the arduino such as this > As I said before each board works individually, the main difference now is I have long leads from a breakout board for each GSCLK, blank, SCLK, GND, V1, V2. and XLat. So if i power on the chips with V1 and everything is ok, then power the arduino and some of the chips instantly fry. So the only difference is GSCLK, blank, SCLK, Xlat are on but that should not cause some of the chips to fry should it? The only other thing is the second ground that is shared being activated which might be solved with the single power supply.

I suppose I also could run everything off a single 12v/9v high current power supply but the excess voltage will be burned up in the FETS, it might not be bad as I have everything heat sinked pretty good.

 I'll get another photo or vid tonight of everything hooked up
43  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: March 21, 2012, 06:30:05 pm
There are three voltage sources. The 5v that powers the chips only, the 5v that powers the output circuits, and the arduino 12v. I'm not sure why it fry's some of the chips while it should work. 50x chips just arrived in the mail, I guess I just have to play around with it.
44  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: March 21, 2012, 05:25:10 pm
Ok so I have six of these boards done for a total of 96 outputs. I have tested each of these individually ok. I have hooked it up just as before except a separate power connection for vcc for the chip.

I power on all the chips, wait a few min and they are all fine and cool to touch.

I plug in the arduino that has a different power source with a shared ground and 3 of the chips fry.

So I'm not sure if a wire has came loose in my temporary setup or how to hook this up without frying the chips.

I know they are fried because I hook them up again with only vcc and ground and they are extremly hot.

I can replace the chip, hookup the arduino directly to  the board instead of a breakout boards of greyscale clock, blank, etc and the board works ok. I know you said that working with higher powered stuff complicates things but this seems more like a hookup issue than a decoupling issue.

Feel free to ask questions, I feel like this can work but i'm just missing something simple.
45  Using Arduino / LEDs and Multiplexing / Re: 6x TLC5940 32 rgb leds on: March 01, 2012, 07:49:24 am
The chips seem to do just fine as long as I plug them in the right order with no heat.

I have a bunch of 3w rgb leds with 350ma per led and a HengFu with two 20amp 5v outputs. The r3 resistor I used a 1.5ohm 2watt. I planned on providing 20amps 5v per board which I think should be ok but I don't think my multimeter can handle that kind of current to actually test it to see how much it's pulling. I plan on having up to 6 boards per art piece. While I think it should work i'm not sure if its the best practice. From my understanding I could have a higher voltage power supply for V2  and the extra voltage will just get burned up in the FET. Would that be a better option, or would it just be less efficient?
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