12V Resistor and 12V Regulated WS2811 Pixels

BRW

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Given this experiment and real life experiences, what would you recommend that someone just starting out procure? If costs were the same it seems like regulated is the way to go. But is the cost difference enough to buy resistor pixels instead? In the future will pixels move towards regulated? Or will they always be a subset of the offerings?

I'm completely new and working to spec what I want for a show in this next year.

Thanks!
 

TerryK

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Unique opinions make recommendations difficult. Quite a few ACL members, if not all, have their preferences why they choose 5 Volt over 12 Volt, Resistor over Regulated pixels. And there are those who have a mixture.

My opinion and referencing WS2811 round bullets only, 5 Volt pixels seem to be the cheapest, 12 Volt Regulated the most expensive. The regulated 12 Volt pixels are the most immune to voltage drop and somewhat puzzling the 12 Volt Resistor the least (I expected the 5 Volt pixel to be the least). A 5 Volt supply will drive more total pixels (I think I can accurately say that) than a 12 Volt supply. Loosely comparing the LRS-350-12 and LRS-350-5, they are 29 Amp and 60 Amp respectively. Quite a bit of that difference is converted to heat in the pixels; 12 Volt pixels still have 5 Volt innards. The extra 7 Volt (12 minus 5) has to go somewhere.

Can't say where pixels are going. Efficiency aside, it seems to be slowly moving towards 12 Volt Regulated but that could change tomorrow.
 
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SAALTFAM

Sparky with Blinky Lights ;-)
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The never ending debate
WS2811 vs ???? Or any other.
Falcon vs PixLite vs Kulp vs ???
Wireless vs LAN.
The truth is, use what works for you and are comfortable with as it is your display and you spend the time to make it, you may need help but that is why we are all here.
We are all different but we all like flashing lights and we all like to help.
Just enjoy the smiles and joy your light bring to others.
 

BRW

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Thanks for the input. I really hadn't been thinking of 5V, but the layout I'm considering would allow their use. I guess I was thinking about the simplicity of a single solution - but now I need to open up my considerations.

Appreciate it!
 

TerryK

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I would suggest either a 5 Volt or 12 Volt display. Care needs to be exercised in mixed voltage displays to avoid 12 Volt fed to 5 Volt pixels.
 

Tim Hutson

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This is my third year with an LED light show. I have a combination of strips and pixels with 15,000 totals pixels/nodes. I am already looking to add some matrices to my show for next year and started looking at Ray Wu's latest pixel offerings since I will be using pixel nodes instead of pixel strips for the matrices. This is the first time I noticed Ray had both resistor and regulated pixel nodes. Not sure what I currently have because I don't believe he had both in the past. However, what caught my attention was something that has not been discussed above. His regulated pixels are 0.6W and 50mA, whereas the resistor pixels are .24W and 20mA. That is a huge difference and has a massive impact on power design to include power supply size, injection, etc. Assuming Ray's data is accurate, and notwithstanding all of the discussion earlier regarding this subject, why would anybody ever choose regulated over resistor pixels? I feel like I have completely missed something. Any explanations?
 

Old Salt

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My understanding is that the pixels run on 5V, whether they are on a 12V or 5V string. The pixels on a 12V string use either a resistor or voltage regulator to drop the voltage to 5V for its own use.

OK, then why do we have 5V strings and 12V strings?

The answer is line loss. Every piece of wire has resistance. The voltage lost is equal to the current times the resistance. As you move from the first to the last pixel on a string that resistance increases, thus decreasing the voltage available at that pixel. With a 5V string, you can't afford to lose much voltage before you get color distortion due to the low voltage.

In a 12V string, the voltage needs to be dropped, before it's fed to a pixel. For those with resistors, a single value is chosen to drop the voltage within acceptable limits for the pixels. The voltage applied to each pixel will vary, depending on its position within the string. You can still get color loss due to low voltage, but it won't be as noticeable as on a 5V string of the same length, with the same number of pixels. If each pixel has a regulator, they all will get the same voltage, as long as there's enough left for the last pixel - so no color distortion due to low voltage. The disadvantage is that the regulators also use power, thus more is needed and the line losses also increase.

Higher supply voltages, resistors, and regulators are methods used to extend the string before power injection is needed. Another method would be to use wire with a larger cross section which lowers its resistance. For example 20AWG copper wire has a cross section of 1000mils and a resistance of 10Ω / 1000ft while 18AWG has a cross section of 1563mils and a resistance of 6.4Ω / 1000ft. Just as a reminder, a pixel one meter from the connector end of a conventional string has a current path of double that, one meter to get to the pixel, and one meter to return to the connector.
 

i13

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I was under the impression that regulated 12V pixels drew less current and therefore power than those with resistors which presumably draw 55mA. Maybe the 46mA reading means that there isn't much of a difference or it is at least smaller than I thought. I don't have any of the resistor type nodes in order to measure this for a comparison and nor have I measured the current draw of my regulated nodes.

In my display, I have some 12V pixel icicles from Ray that are the regulated type. These run end-to-end with a 12V WS2811 pixel strip. The last pixel in the icicles should therefore get approximately the same voltage as the first pixel in the strip. When I first tested everything, voltage drop was a problem in the strip but not the icicles.

It is clear that the regulated pixels are a better product than those with resistors but there's still a place for 5V.

Thanks for all of the info in this thread.
 
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Old Salt

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They'll draw less current, perhaps. Power is calculated as voltage times current.

As the LEDs are probably the same for both 5V and 12V strings, the current is the same for both. Let's assume (I know) that the current through each LED is 30mA at full brightness, and that the voltage at the control chip/LED is 5V (for both). Then, with a resistor, we'd need to drop 7 volts before we hit the control chip/LED. It's a series circuit, so we waste 7V X .03A or .21W per pixel. The actual power used by the control chip/LED is 5V X .03A or .15W per pixel. We lose .21W/( .21W + .15W) * 100 or 58%. That's the easy one.

We need to drop the same 7 volts, if we use a regulator, but a regulator can take several forms. I don't have a regulated pixel string here, but they generally work by monitoring their output voltage, and conducting only while that voltage is low. The total current and power loss for regulated pixel strings should therefore be lower.

I'm using 5V strings wherever I can, with power injection where needed. Twelve volt (regulated) strings will only be used where the 5v strings are too long for 5V to work. Note that even the huge 2000 pixel props will work well with power injected 5V strings. Long pixel runs such as those for house outlines, and megatrees etc will be 12V regulated pixel strings.
 

Tim Hutson

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Since the four most recent posts came after I made my first post yesterday I assumed they were in response to my post, but I think they were actually in response to posts from a couple of weeks ago since they talk about 5V vs 12V pixels, voltage drop, line loss. etc. (which I fully understand by the way), but have nothing to do with my question. Just in case they were addressed towards me, thank you very much, but I guess I need to further explain what I was asking.
First, both of the products I found from Ray Wu are both 12V pixels and both are identically priced. The only difference in description is one is regulated pixels while the other one is resistor pixels. However, my question was in regard to the specifications of each of the two products. The regulated pixels have max power and max current of 0.6W and 50mA respectively, whereas the resistor pixels have max power and current of .24W and 20mA.
It is this huge discrepancy in power draw that prompted my question. Based on Ray's specifications, the regulated pixels require 2.5 times the power which is why I asked how anybody could justify the additional power infrastructure to support their use. This makes no sense.
Frankly, I suspect Ray's specifications are incorrect but I thought I would start with you guys. By the way, the pixels I have now are based on his previous pixel node specification of 66mA which is different than both of his present offerings. Have there been product improvements?
I am going to insert the links to the two Ray Wu product I am referring to for further clarification. Hopefully this information clarifies what I am asking. Thanks guys for any insight you can shed.
 

i13

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I suspect that the 20mA value is incorrect. It could be that Ray did a copy and paste from a WS2801 listing and the 20mA is the value per colour. The whole pixel would therefore draw three times that amount. WS2811 pixels are limited to 18.5mA per colour. Some resistor type 12V pixels run the LEDs at 10mA per colour for a total of 30mA and some run the full 18.5mA per colour for a total of 55.5mA. Running a higher current means that they're brighter but they consume more power and are more prone to voltage drop.
 

TerryK

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Chinese product specifications are generally rather vague. One can see this in the IC datasheets as well as the pixels. As to Ray's specifications, I think Ray's spec is 'in the ballpark' but not accurate. I have some 12 Volt Resistor WS2811 bullets and at 100% white they run about 32 mA. Five Volt and 12 Volt Regulated WS2811 bullets at 100% white run approximately 48 mA and 49 mA respectively. However I also need to mention that I encountered testing errors while testing and do not consider those values extremely accurate. When time allows I plan on re-testing.
Regulated pixels are more immune to voltage drop but I'm not sure I would call them better. Rather, they would have an advantage that one might strategically use for a particular reason. It's quite possible the same individual different scenario might choose a different pixel.
 

SAALTFAM

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One may be for each colour and the other for the whole pixel.
Read and then compare to the average values of 20mA/colour and 60mA for three colours at 100%
 
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