whats the max. distance between two ws2811, 5v, 8mmleds, sop-8?

Archive FastLED Archive
,
1

whats the max. distance between two ws2811, 5v, 8mmleds, sop-8? i like to connect some strings with a distance between every 50 leds. thanx for tips and answers

2

Hi,

I did tests with a very long 30 feet of 22AWG 3 wire between 2 pixels and it worked fine. However I only had 1 pixel worth of current (<60 ma.) so there was not a significant voltage drop on the +5V. Can’t remember how much voltage drop it was but the far end pixel actually worked fine.

You need to be concerned with the total amount of current over a long length. For a long length with lots of current you would have to get a larger wire on the 5V and GND wires to minimise the voltage drop.

3

From a led power voltage or Fastled signal perspective?

4

The WS2811 chip regenerates the signal at each pixel. Data comes in and the chip strips away a pixel’s worth of data and transmits the rest to the next pixel. To work properly the chip needs enough power (volts and amps).

Search the internet for a voltage drop calculator to see the impact that distance and wire gauge have on voltage. Remember a 1 volt drop on a 5v system is a 20% loss.

5

thank u, that can i use for calculating

6

@Mike_Thornbury From a LED power perspective. The data input current on the WS2811 or WS2812 is measured in the micro amp range and will not drop in voltage significantly even in long wiring lengths.

However, that type of data signal do degrade over long lengths but not due to DC voltage drops but mostly for noise pickup and crosstalk reasons.

I have just now quickly redone my test over the same 30 feet of 22 AWG 3-wire RGB cable and actually measured the DC volts at the end where I have a single WS2811 module with a 8mm RGB LED and the LED works perfectly again !!

My Arduino Uno is powered by USB and indicates 4.98Vdc on board and at the far end I measured 4.79Vdc when the pixel is on Full white !!!

Notice that if I had let’s say 10 of these pixels instead of just 1, I would likely have more or less a 2 volt drop over that same length now and that would no longer work properly !!

7

Here is a voltage drop calculator that lets you input your own info… http://www.calculator.net/voltage-drop-calculator.html

Sending power to a single pixel over 30 feet (0.06 amps full white) will give you a 1% voltage drop on 22 gauge wire.
sending power to 10 pixels (0.60 amps full white) over 30 feet will give you an 11% voltage drop on 22 gauge wire.

These calculations don’t take into account the voltage drop of the pixels you have before the 30 foot wire run.

You can lower the voltage drop by using a larger wire (smaller gauge) or by injecting power at multiple points along the string you are powering. Just make sure to connect the grounds from each power supply feeding the LEDs are connected together.

8

@Michael_Sharnet

That is a very useful calculator and expect that the results it provides are accurate.

However, I am looking at my quick setup of a single LED connected over a 30ft length of 22AWG 3-wire cable and I am trying to figure how I actually measure a 3.8% voltage drop as I do trust my measurements !!

Here’s my assumptions…

  1. My wires look silvery and are actually not pure copper but some unknown alloy (I am guessing that is where most of the discrepancy resides)

  2. Is my wire actually 22AWG ?? (Considering Chinese manufacturing here and some form of spec stretching…)

  3. I only estimated the 60ma current draw. (20ma per LED is a common number but I did not do actual measurements) could it be more or even less !?!?

  4. Did not measure voltage drop across the small connector (I initially assumed it was not significant but was it ?)

9

thank you, i’s the first time, i’m making a installation whit 1000pixels and your answer was very important for me.

Von meinem iPhone gesendet

10

Typically Chinese wire is sold by the metric sizes. Here is a conversation link http://www.csecables.com/technical-tables-useful-info/awgmetric-conversion/
Reminder when converting ma to decimal
60ma = 0.060
20 ma = 0.020

LEDs are designed for 20ma x 3. Design and actual will vary. Additionally the WS2811 may add to the current draw.

11

well mine was sold as 22AWG and it is actually stamped as such on the wires.