Sanity Check/Parts list

I already have a pixel blaze here on my desk and the 8x8 matrix that I have been experimenting with.

Can anyone give me a sanity check and find any flaws with my parts list for an installation on a car?

3x spools of this:

2x psu:

and of course expansion boards:

I already have a few 3a TI based linear (buck) converters to handle the power for the blaze and the expansion boards.

i will likely be pushing around 700 pixels for this project. I appreciate if anyone is available to punch holes in my bill of materials or make suggestions otherwise.

edit: i just noticed the output expander does not specifically mention the gs8208’s. however they are supposedly interchangeable with the ws2815’s from what I can tell. Any verification on this would be great.

Thanks in advance,

Looks pretty good! 700 of those LEDs will be 14 amps, and your two power supplies of 8.5 amps each should be ok if you split the load evenly. But check the temperature derating curve of the SD-100A to be sure you can supply enough power at whatever max temperature environment the power supplies will be in. Also make sure the cables from your car +12V to the power supplies are beefy enough so the input voltage at the power supply doesn’t drop below 10 volts. See graphs on the SD-100A spec sheet for temperature and input voltage derating.

Excellent, thanks. I am pretty good with figuring my wire gauges. They gonna have to bee thicc depending on the install location. i may have to upgrade the alternator and battery. The psu’s are gonna have to be under the seats or under the dash in the cabin. I’m thinking that i may limit the brightness curve so even at max output i shouldn’t pop one… this is why i went with meanwell, overcurrent protection, undercurrent protection, etc. i may also install a small fan on each psu as they are fanless.

Hi Gabe,

As a recent fan of the GS8208, I just wanted to caution you to confirm with SuperLightingLED that this version with the offboard chip does NOT do the built-in test patterns. They are really annoying if present.

The WS2812 setting on v3 works great with my (controller chip built-into-LED) GS8208. I haven’t tried it with the output expanded but I imagine it’d work fine.

Power looks good. FYI: Quindor measured .206 W/LED max on some GS8208s, and I measured .146 W/LED max. Using his as more conservative, that implies that each of your 100W PSUs can have up to 485 of your LEDs on it.

On the 12V 5m 60/m strips, I like to inject every 300-600 pixels (and they take full white current for any one color being on), so if you want full white at times without yellowing, maybe plan for being able to add some power injection based on your own testing. My guess is it’ll probably be fine and unnoticeable.

I’ve never done an automotive install. Is the purpose of the SD-100A012 clean up the car’s 12V? Since I recently spent many hours reading Meanwell datasheets, just wanted to point out this one is rated for 2G vibration; that’s on the lower end of their available vibration specs. Would this be protected from moisture? (edit: I see they’re under seat). To @Irwin’s good point, these supplies start to derate at a relatively low 40C/104F.

Sounds like you know how to fuse these correctly.

A quick look at the RSD-200 shows 5G vibration and about 80% less thermal waste per watt. (89% vs 82% efficiency). They start derating at 55C/131F.

Maybe the fans you would add are quieter, but the fans on my LRS350 and RSP320 are annoying my family this holiday season.

my voltage input is going to be around 11-14v as it will be right off of the car battery. The listed spec for minimum input voltage for the rsd’s are 16.8v hence the dual 100w models can have a minimum 9 or 10v input. Thanks for noting the vibration rating. In my experience you can drop a power supply off of a desk onto concrete (ooops) and they’ll still work (most of the time). I can also install rubber grommets to reduce vibration from the chassis. if all else fails, I’ll reinforce the innards with hot glue or just warranty return them til i can find something that works. :smiley:

as for your note on the g8208’s, i’m pretty sure they all have the built in test patterns. but i plan on the entire system being switched off when not in use. AFAIK the only time the test pattern comes on is when there is no data signal. and yes, the extra 80 dollars in power supplies are to hopefully isolate noise and utilize the protection circuitry and ensure I do not have voltage fluctuations. The reason I selected the gs8208’s over the ws2815’s is that I had read somewhere that the ws’ are more susceptible to radio interference (allegedly put cell phone near the strips). I don’t want to have to spend time or effort figuring out where electrical noise is coming from if I can avoid it. I realize that there are ten thousand cheap power supplies on the market, but meanwell has always done me right for motion control systems like that on my 3d printer. I plan on trying to sell these installs in the future, so the easier the labor portion is, the more I can focus on selling more and having people pay me for custom programs. :smiley:

Thanks for the note on length of power injection. my longest runs SHOULD be about 15 feet (roughly 3 meters) @ 60 leds per meter i’m sittin at around 200ish pixels per run. of course… if i can get away with less wiring, I will be much happier.

Regarding the relationship between current draw and brightness: there is (almost) none! The GS8208 uses a unique design where the three RGB LEDs are connected in series, and the chip provides a current shunt across each one. Each pixel will draw the same current (about 20mA) no matter what color or brightness level it is (except of course, completely off). So reducing the brightness will not reduce the current draw of your system.

crap… good to know though. Any idea of the ws2815’s suffer the same flaw?

See Is the pixelblaze v3 compatible with GS8208 LED strips?

I believe the WS2815 works the same way. But is is not a flaw! It allows each pixel to use only 1/3 the current at full brightness as compared to other designs that put the LEDs in parallel.

So overall more efficient, but brightness doesn’t control consumption. got it.

Alright. good to know. Thank you for finding that for me.

Brightness (single color max) does control consumption, in both GS8208 and WS2815. The WS2815s also use this 12V design where any one color at high current causes the other colors to be shunted by the MOSFETs and thus uses 3 * max(r, g,b).

The only efficient 12V systems are the ones that have regulators built-in to the strips. Here’s a premium product like this, and here’s one that has a noticible but acceptable failure rate according to online experiences shared.

While I don’t know about the GS8208 RF rejection, I do know their built-in gamma curve is really nice, and noticeably better than any WS28XX:

@jeff you are right, but I gave the worst case scenario.

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@Irwin, totally. I appreciate it. And in practice, a lot of patterns will draw close to max.

One thing I measured to my surprise though - Quindor measured 17mA max through of some, which is on-par with current in 5V strips; the ones I ordered though, I can’t get more than 12.2 mA going through any pixel; this is much like my WS2815s where I get 11.5 mA per pixel max.

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That video is excellent in showing the difference. looks like the 2815’s are 3030’s and the 2808’s are 5050. didn’t even realize by the product descriptions i was reading. Brightness stepping is going to be important in my application. so gs2808’s it is. I think i will order the same ones from your other post from ali-express (provided it doesn’t take 6 months to arrive) as they are WAY cheaper, and if they don’t have the test pattern, all the better. :smiley:

This is lower than I had originally assumed. great information.

Thanks everyone for the input and responding so quickly. So much as been clarified in my brain so quickly.

If I run into any more issues I will definitely post.

another user had found these

12v apa102’s… any thoughts on this. As i looked at the shipping time frame from aliexpress and it’s over a month. these be any better than the gs2808’s? They are nearly the same price. about 15 bucks more for the same quantity.

wait, scratch that. these apa’s are only 1m each for the same price. gs2808’s it is. :smiley:

Hi Gabe,
A few notes/clarifications, I think mostly covered elsewhere, just wanted to mention it here just in case.

  • GS2808/GS2806 with built in patterns can look glitchy sometimes when there is a pause in data. Pixelblaze may pause data when switching patterns or saving data to flash, or if there is a code error in a pattern.
  • I’ve had some reports that gs2808 can fall back to a 400khz data mode, mostly reported with V2 Pixelblazes. I think they look for certain timing clues, switching automatically, and are thus not as forgiving as WS28xx type LEDs and other clones. In general the output expanders and V3 have more conformant data signals than V2 does (though V2 has more flexibility in data rates).
  • Both GS2808 and WS2815 12V LEDs work by running the RGB elements in series so that they use the same current/power regardless if they are turning on a single element, 2 elements, or all 3. They will still use less power with lower brightness levels.

I’ve measured WS2815 @12V using 12.04mA to 12.58mA when drawing at full brightness. The lower current figure is actually white, and the higher value is a solid color, I’m not quite sure why. I’ve seen them draw 1.85mA when idle / black.

I don’t have figures for the GS2808 but I suspect it is similar.

@jeff Quindor’s measurements are at the AC input to his power supply (or at least originally were), so you have to figure power supply conversion losses (the efficiency of which varies by load). That data is good for relative comparison, but not going to translate to what you would measure on a multimeter or what you would use to calculate your output load requirements.

@Gabe Keep an eye out for some tricks used in other 12V addressable LEDs, like that 12V APA102 strip you linked, that will most likely run 3 LEDs in series (not elements), meaning each “pixel” is actually drawn on 3 different LEDs. Good for zone lighting, but not fine-detail pixels.

Yet another thing to look out for is inefficient 12V addressable LEDs that wire single elements to parallel lines, for example WS2811 can be used with 12V to efficiently drive 3 LEDs per pixel, or a single LED inefficiently – both configurations draw the same current/power, but with the single LED setup the extra power is lost as heat.


@wizard" Keep an eye out for some tricks used in other 12V addressable LEDs, like that 12V APA102 strip you linked, that will most likely run 3 LEDs in series (not elements), meaning each “pixel” is actually drawn on 3 different LEDs. Good for zone"

When you look look at the strip how do you tell the difference?