E682

[k6ccc]

A null pixel is just another pixel in between a long run for the data. In the SanDevices controllers you tell it that there is some number of null pixels. I assume the other controllers are similar. A null pixel does not exist as far as LOR software is concerned..

[sax]

A null pixel is just another rgb pixel. It is used to carry the data signal on.

The problem is, over great distances the data signal degrades. But with a null pixel, the data signal comes in degraded and is sent out whole again. This also takes some of the voltage at the pixel.

So pixels are good for data signal but bad for the power supply.

I can only get the data to go about 20 ft before it degrades on a standard E682. By changing the resistor packs on the E682 I can go further, currently I have only tested out to 25' as that is my longest extension cable. The power supply voltage, I use 12vdc, can go much further. But to allow me to get the data out further, I have to put those pixels in to boost that degraded signal.

If you don't classify the pixel as null in your controller, then it is just pixel one. In truth you can have your pixels spread apart as much as you want as long as you can get the data signal and power to it. But in most cases you want them grouped on your element.

By classifying the pixel as null it is simply ignored by the controller as a working pixel.

If you classify more pixels as null than you have, you just push pixel 1 further from the controller. It passes the data on, but the pixel doesn't light.

Your null pixel has to match the pixels you have on that output. So if I have 2811 pixels the null must be a 2811. It can be a different shape, say flat over bullet...but it must be the same type.

My null pixels are simply a bullet 2811 pixel with pigtails on both ends to allow me to insert it anywhere I need it.

Hope this helps anyone confused over nulls

Edited March 8, 2015 by sax

[Steelers95]

what type of wire/ what gauge do you use to connect the pixels to the controller and the controller to the power supply?

[k6ccc]

Most of mine are using 4 conductor 16 AWG speaker wire. Since 2811s only take 3 wires, I double up the ground.

[anthonyrusso3]

It Helped alot, Thank you Sax. Now does anyone know why my power supplies stop working 12vdc 350 watt 29 amp ran 16 strips, 50 12volt square pixels  works fine during testing about 20 minutes, shut it down and when I went back to use later no power ?   Bought on Amazon.

[larryk5]

A side question about null pixels. Has anyone attempted to use a bad pixel as a null pixel? One that may have been cut out of a string of pixels. Would they work as null pixels?

[k6ccc]

A side question about null pixels. Has anyone attempted to use a bad pixel as a null pixel? One that may have been cut out of a string of pixels. Would they work as null pixels?

 

I guess it would depend on what failed.  However from my experience, it's the IC not the LED that fails so it would not work as a null pixel.  Often the failure mode of the chip is that it causes all downstream pixels to become full white.  I know that for the few pixels I have had fail and had to replace, the failed one immediately went into the trash.

[larryk5]

I guess it would depend on what failed.  However from my experience, it's the IC not the LED that fails so it would not work as a null pixel.  Often the failure mode of the chip is that it causes all downstream pixels to become full white.  I know that for the few pixels I have had fail and had to replace, the failed one immediately went into the trash.

That makes sense, I would of thought the LED would have a higher failure rate than the IC. I'll have to try one sometime and see what happens.

[sax]

what type of wire/ what gauge do you use to connect the pixels to the controller and the controller to the power supply?

This is what I use for my extensions.

http://www.aliexpress.com/item/7-6-25feet-long-4core-BLACK-extention-cable-one-end-with-male-the-other-end-with/804982353.html

I use his 5', 10', and 25' extensions.

Up above in this post is a link to a post in these forums titled "wire type does matter". Lots of information in that post. I did purchase some of the shielded thermostat wire that others recommend, but I wanted something off the shelf that worked to save me time and money. By changing my resistor packs, which is also talked about in that post, I am able to get these extensions to work.

That expensive thermostat wire is still complete and on its roll never touched. I am saving it for the day I go to 5v and start having issues. If I go to 5v, I will try everything I can not to use that cable. But I choose to keep my controllers at a central location....so that might cause issues.

[sax]

It Helped alot, Thank you Sax. Now does anyone know why my power supplies stop working 12vdc 350 watt 29 amp ran 16 strips, 50 12volt square pixels  works fine during testing about 20 minutes, shut it down and when I went back to use later no power ?   Bought on Amazon.

I would disconnect output on supply and then turn it on and test output voltage. Power supplies do fail.

I had some flickering in my show this past Christmas on my dumb lights. The power supply was the last thing I checked because I thought for sure water was causing the issue by seeping into my extension cables. But nope, my power supply was bad.

So check that supply first would be my advice.

[Darryl Lambert]

A side question about null pixels. Has anyone attempted to use a bad pixel as a null pixel? One that may have been cut out of a string of pixels. Would they work as null pixels?

 

That's what I did. I had some pixels were the red LED was dead. So I used them as null pixels & it worked fine but if the ic is bad I wouldn't bother to try.

[Max-Paul]

I guess it would depend on what failed.  However from my experience, it's the IC not the LED that fails so it would not work as a null pixel.  Often the failure mode of the chip is that it causes all downstream pixels to become full white.  I know that for the few pixels I have had fail and had to replace, the failed one immediately went into the trash.

 

Yet two years ago. I used some of Mr. Wu's WS2811 5 mtr 12V strips. Had about a dozen sections that would no long light up the Red LED and I think one or two sections that the blues would no longer light up. As I remember it, the general consensus was that the LED were burnt out cause the resistor was not high enough to keep the current below 20mA thus burning out the LED element. So the WS2811 chip should be in good shape.

So, I am not sure as to what your referring to, but those strips from several years back should work fine for null nodes per each 3" section. BTW the reason I know is that I bought some 5050 LEDs from SupperBright and discovered that even though all of the cathodes were on the right side of the LED. The oder was off and would light up the wrong color. But it did function on the WS2811 level.

[CLD Kevin]

I see somewhat a valid point in using bad pixel for a null but personally if anything is wrong with a pixel...whether it's a led or IC....I trash it. You have a greater chance of something going bad if your using something that is already showing signs there is an issue. Why take the chance saving $1 when you have $$$$ invested. If you think you need 3 or 4 null pixels...have 5 or 6 built, ready, tested and on standby. That goes for everything. Easier and less headaches to replace than trying to figure out at night in zero degree weather. GOD forbid you're soldering in that weather. No thanks!! Just my 2cents.

[k6ccc]

I'm with Kevin on that one.  My time is more valuable than that.  I figured it took almost 15 minutes to cut out a bad pixel and replace it (including soldering, taping, and heat shrinking).  That does not include the time to get out the tools and ladder.

 

And all that to put in a pixel that is already suspect?  No way!