5v vs. 12v Pixels

**rsegreto** · 01-15-2021, 07:11 PM

Any reason I couldn't use 18G / 2 Copper Monoprice speaker wire to run just the Data / V- to the first pixel?

https://smile.amazon.com/Monoprice-N...746391&sr=8-14

**MartinMueller2003** · 01-15-2021, 07:15 PM

Originally Posted by DrNeutron

I have been using these for past 3 years: https://www.aliexpress.com/item/3235...27424c4dxZRVnt
I love the small size and 40amps is plenty for my uses. This particular seller has good prices at times but you have to watch for it.
In this case he has 11% off a lot of 2, but if you buy 3 he takes 40% off entire lot before taking the additional 11% off.
With shipping it works out to about 16$ cdn a PS delivered.
I know people will bash the "cheap chinese" power supplies but they have worked fine for me. I don't need a fan on the PS as I live in northern climate so temperature is not an issue.
I can fit one of these in a CG1000 along with 2 power distro boards no issue.

a bit of overkill but it will work. i use 22awg wire for 10m runs with no issue

**rsegreto** · 01-15-2021, 08:51 PM

Okay great even better! I just assumed since that’s what most strings used so thought it should match.

What gauge are the pigtails? I’m going to tie directly into one so just curious.

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**jchuchla** · 01-15-2021, 09:03 PM

Originally Posted by rsegreto

Okay great even better! I just assumed since that’s what most strings used so thought it should match.

What gauge are the pigtails? I’m going to tie directly into one so just curious.

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The power lines benefit from larger gauge wires. The data wires don't need large size. 22 or 24awg is fine for the data and it's ground reference.

Most pigtails and quality pixel wire are about 20 gauge. (even when it says 18) cheap pixels use 22 or smaller.

**rsegreto** · 01-15-2021, 09:06 PM

Awesome thanks! Save a few bucks on the thinner wire.

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**munu** · 01-16-2021, 03:28 PM

I was going with 12V LEDs because I wanted to reduce the number of PIs but now I am reconsidering this choice due to power consumption. Next year will be my first pixel display so it will be small. But I am sure it will expand and so power consumption might become an issue.

Is the voltage amperage relationship something intrinsic (for a particular wavelength) that cannot be change by design of the LED? Googling this it seems that might be the case. So there really aren’t any 12V LEDs but just setups where an LED/resistor combination can take more voltage and burns up more wattage in the resistor. That kind of doesn’t make sense (unless maybe you take ‘system’ requirements into account).

So if you have a series of pixels the current through all pixels must be the same (only protons can kill electrons…). So what changes from pixel to pixel is the voltage. Let’s assume your voltage droppage from one pixel to the next is x. Also your pixel need at least 4V to be at full brightness (without burning out). So you can have (5V-4V)/x number of pixels. With 12V pixels you can have (12V-4V)/x pixels. So all you do with 12V setups is getting more pixels at the cost of burning up more wattage in the earlier pixels in a string.

Does this logic make any sense? If so, I really have to reconsider my decision to go with 12V pixels. I based this on a lot of comments from people on this forum. I came away with the impression that most go with 12V to reduce PI but maybe that’s not the right decision. Or I guess it depends on the situation, i.e. for a roofline that is long 12V might be better but for arches and mini trees, maybe even mega trees 5V is better?

**MartinMueller2003** · 01-16-2021, 04:50 PM

I have consistently been saying 0.3W/Pixel is better than 0.72w/pixel when you start talking about 10,000 pixels. I have 9 12v strips in my show. Everything else is 5V and I have no plans to move to 12V pixels. For me, the reduced number of power injection points for 12v pixels does not offset the recurring costs of powering the pixels. I power inject power in the center of groups of 25 pixels (12 left 13 right) using buck converters. On my megatree I have 16 14AWG feed lines and inject every 25 pixels. Once you decide to save power and do power injection things get simpler.

FYI: The "Regulator" based 12v pixels still consume the same amount of power. You have to have converter style pixels to get the power savings. The regulator based pixels allow the voltage at the pixel to drop as low as 7v before you get a loss of intensity.

**jchuchla** · 01-16-2021, 06:32 PM

Originally Posted by munu

Is the voltage amperage relationship something intrinsic (for a particular wavelength) that cannot be change by design of the LED? Googling this it seems that might be the case. So there really aren’t any 12V LEDs but just setups where an LED/resistor combination can take more voltage and burns up more wattage in the resistor. That kind of doesn’t make sense (unless maybe you take ‘system’ requirements into account).

Yes, the voltage, amperage relationship is fixed. This is electronics 101.
P = I * V
P is Power in Watts
I is Current in Amps
V is Voltage in Volts.

12V pixels will use more power than 5V pixels because all pixels are inherently 5V. (ignoring finer details for the sake of simplicity) The LED and drive circuit need about 5v to work. For this to work on higher voltages, there needs to be something else in the pixels to transform the higher voltage to 5V. This is either done with a resistor, or a regulator. The two mechanisms work differently, but they both will convert the excess voltage to heat. Whether or not that heat is useful or just wasted energy is a matter of opinion.
One exception is with multi-LED pixels where there's multiple (usually 3) LEDs per color. In these cases, the resistor/regulator only drops power to the drive IC, and the combined Vf of the multiple LEDs comes very close to the actual 12V. These are generally more efficient than single led pixels because there's less energy converted to heat.

FWIW, I use 12V for everything and do not power inject at all. I find that the design simplicity is worth the extra energy use.

**rsegreto** · 01-16-2021, 06:54 PM

Originally Posted by jchuchla

FWIW, I use 12V for everything and do not power inject at all. I find that the design simplicity is worth the extra energy use.

Do you not have any runs over 100 pixels or do you get away with longer strings w/o PI? I believe the videos of your sequences that I saw had house outlines, how did you get away w/o PI there?

-Russ

**munu** · 01-16-2021, 08:08 PM

Originally Posted by jchuchla

Yes, the voltage, amperage relationship is fixed. This is electronics 101.
P = I * V
<snip>
12V pixels will use more power than 5V pixels because all pixels are inherently 5V.
<snip>
FWIW, I use 12V for everything and do not power inject at all. I find that the design simplicity is worth the extra energy use.

Maybe I was wording it wrong. I was aware of the P=I*V. I was just wondering if "I as a function of V" could be changed by changing the design of the LED. For instance instead of letting 20mA through at 2.5V it would let 20mA through at 7.5V. But I guess then you would be back at square 1 regarding PI.

How many lights are you running and from how many independent 110V outlets? My wife does complain about the December electric bill but I am ok with that if it makes my setup easier and cheaper by having to buy fewer cables for PI and fewer electric boxes with F48 differential controllers.

Do you know how many watts you are actually using? It seems watts calculated according to the spec sheet are much higher than what is really used.