Cutting a pixel strip and controlling it.

[Ed Slonka Jr]

Have a question about cutting one of these strips and controlling it.

http://www.aliexpress.com/product-fm/519162566-5m-led-digital-strip-DC12V-input-WS2801IC-256-scale-12pcs-IC-and-36pcs-5050-SMD-RGB-wholesalers.html

I would like to make 2 out of 1 to use in my display. I currently have one and got it up and running and
have done some sequencing using Superstar and then into LOR 3. So far so good and has come out
pretty well.

But what I would like to do is cut it in half as I said and have 2 and then get another to have 4.

When I cut it would it be better to run wires to treat it as one ribbon thus using 2 controllers or use
4 controllers one for each ribbon and set the starting address on each controller?

I am using this controller: http://www.aliexpress.com/fm-store/701799/209915969-509914025/LT-DMX-2801-DMX-SPI-Decoder-support-WS2801-WS2803-drving-IC.html

Thanks, Ed

 

[oldmanfathertime1000]

Yes you are on the right track. You can cut these strips on the cut marks to any length you want. You then treat each of the cut pieces as a seperate strip. If you want to control each piece seperatly, then you need a controller for each piece. You will have to supply power to each of the strips. You also have to set the address each of the controllers.

 

[fasteddy]

You can use the one controller to control one strip that has been cut up as long as you dont exceed the number of channels that the controller supports. You just join each cut section together as each pixel will regenerate the signal which will allow 2 or 3 metres between sections. As far as how you set this up and sequence in LOR S3 im not sure but this is easily done with LSP and is how i did my candy canes.

 

[Ed Slonka Jr]

Thanks Guys!

Most likely will control each strip with a controller and power.

I think I would exceed the 3 meter limit trying to treat as an extension of the same ribbon.

Ed

 

[JonB256]

Ed, that strip uses the WS2801 chip so it might be different, but worth taking a look at this caution.

--------------------------------------------
Edit Note by AussiePhil
The information below is not relevant to WS2801/WS2811 or 6803 Flexible strip. It is however important to TM1809 strips.
---------------------------------------------


On some of the Aliexpress flex strips that use the TM1809 chip, the way they are built means you need to be careful where you cut. While the TM1809 strips show cut points between every 3 pixels (one IC chip and 3 5050 pixels), the way they pass power along the strip is not that simple. While you can cut the "end" safely at any easy to see spot, only every 5th cut point is good for "starting" a new segment.


Look at each cut point. Is there a small black diode next to some cut points but not on every one? On the TM1809s, you can only "easily" cut at the point just before the diode. It is where the 12vdc is transferred from the Power Feed down the back of the strip to a power feed on the front that runs for the next 5 sections. There is, therefore, a diode at every fifth cut point and that is where you should cut for a starting point. That is every 0.5 meters or 15 pixels.


Now, some have experimented and found that you CAN solder in your own diode at that point (there is even a spot for it). I plan to use some of these TM1809 and want a specific length of 72 pixels. Ray Wu will custom cut strips for me of 75 pixels (but not 72, since 72 is not divisible by 5). I can then either ignore the last 3 pixels or cut them off. This problem is related to the START of a string, not the end.


I don't have a WS2801 strip to look at so this may not apply, but it is definitely something to look for.


Jon


update - after looking at the pics in your other post about the "LAT" connection, that strip does NOT look the same as the TM1809, so you may be good to go.

 

[DeeJai]

Thanks Guys!

Most likely will control each strip with a controller and power.

I think I would exceed the 3 meter limit trying to treat as an extension of the same ribbon.

Ed

well, 2 - 3 meters is a guide, I can happily say that through some testing, that using that same strip and a pixad8, I could run a 10m lead from the controller to the strip with no issues, didnt even notice any light degradation near the end of the strip.

2-3 meters is a great rule of thumb, but remember, you could always insert a null pixel or pixel extender (not correct name for it) to extend the gap

 

[fasteddy]

Ed, that strip uses the WS2801 chip so it might be different, but worth taking a look at this caution.

The 2801 strip doesnt have this issue, its when you go use a chip like the 1809 which is a multi output chip that you have these issues. The 2801, 6803 and 3001 can be cut down to the individual sections. This is why i dont believe the TM1809 is a good choice, the TM1803 would be a better choice but again the TM series uses constant voltage as apposed to constant current when driving the LEDs, so for me the WS2801 is the better choice for dimming steps or the 3001 for dimming curves and the 6803 for the price.

I have 4 candy canes using 6803 modules and strip which have a 2 metre lead between them and work great, so in reality you could cut up a strip into each section and make a 2 metre cap between each section because each IC section regenerates the signal.

Th

 

[Bird]

I would like to make 2 out of 1 to use in my display. I currently have one and got it up and running and
have done some sequencing using Superstar and then into LOR 3. So far so good and has come out
pretty well.

But what I would like to do is cut it in half as I said and have 2 and then get another to have 4.

When I cut it would it be better to run wires to treat it as one ribbon thus using 2 controllers or use
4 controllers one for each ribbon and set the starting address on each controller?

Ed, bottom line, if your controller handles a 5M strip, cutting it in half (2 x 2.5M) and running the 4 wires (8 feet or less) between the cut section, you are still controlling a total of 5M light strip. Superstar also allows you to take the 5M strip and cut it in half 2.5M sections for sequencing.

 

[Ed Slonka Jr]

Thanks for all the great info. guys. I have attached some pictures of the strip.
#1 is the start of the strip
#2 is between the 5th and 6th pixel
#3 is a more expanded view
Not really having a grasp of diodes etc. do you see the diode that is refered to by JonB
Thanks, Ed

 

[Superman]

Your good to go with that stuff Ed.

 

[Ed Slonka Jr]

Bird,

That is what I discovered about Superstar and only having a 2 strip license I was going to cut in half and have 4 and with this strip
it ends up being around 81" which is OK this year. If I would try to do a tree like
Brian from Superstar I would then stay with the full lenght to better view the graphincs on the strips.

But doing 4 for this year will add a great new element to my display.

Ed

 

[Ed Slonka Jr]

Thanks Superman (Steve)!

 

[Andrewh]

The TM1809 based strips are one Pixel per Pixel. The TM1809 has 3 RGB outputs per chip, while the WS2801 has only 1 RGB output per chip. When you look at these flexible strips, you could easily think that the 3 pcs 5050 LEDs work together as a single pixel, but they don't. The ones I've seen are 30 pixels per meter, so they have 10 TM1809 IC chips and 30 LEDs. It is "cuttable" on the very visible line after every third 5050 LEDs, but that is because of the TM1809 chip circuitry, not the LEDs.