# MeanWell power supply

#### Jandrews755

##### New elf
Bit of a noob question but how many lights can I run off a lrs 350 12v power supply running at about 50% brightness. Thanks in advance

#### i13

##### Dedicated elf
I am assuming that you're referring to WS2811 pixels but would like confirmation of which type of light you're asking about. Calculating the worst case scenario, WS2811 pixels could draw 0.0555 amps each at 100% brightness. Multiplying this by 12 volts gives 0.666 watts per pixel so you're limited to 525 pixels at 100% brightness. You could double this at 50% brightness but doing so is risky. Running pixels at 50% brightness means you're relying on the pixel data signal to limit the power consumption. If the signal goes corrupt then they might flicker and go above 50% brightness. If you want to use this approach, I suggest fusing everything and leaving more headroom in the power supply capacity. Expect to blow the occasional fuse if you misconfigure the brightness. I also suggest measuring the actual current that the pixels draw because it is often significantly lower than 0.0555 amps. Note that if you're using pixel strips or modules with three RGB LEDs per pixel, you're still limited by the total number of pixels, not the number of LEDs because the three are arranged in series within each pixel and the same current flows through all of them.

I also suggest choosing the higher quality RSP power supply if you can get it at a similar price. This would apply if you plan to have a large display with multiple power supplies.

#### Jandrews755

##### New elf
Yes using WS2811 thankyou that's very helpfull. It's my 1st year so I'm just going to start with 2 power supplys and couple of props and build on it year on year. Thanks so much for your advice

#### Indigogyre

##### New elf
Generous elf
I am assuming that you're referring to WS2811 pixels but would like confirmation of which type of light you're asking about. Calculating the worst case scenario, WS2811 pixels could draw 0.0555 amps each at 100% brightness. Multiplying this by 12 volts gives 0.666 watts per pixel so you're limited to 525 pixels at 100% brightness. You could double this at 50% brightness but doing so is risky. Running pixels at 50% brightness means you're relying on the pixel data signal to limit the power consumption. If the signal goes corrupt then they might flicker and go above 50% brightness. If you want to use this approach, I suggest fusing everything and leaving more headroom in the power supply capacity. Expect to blow the occasional fuse if you misconfigure the brightness. I also suggest measuring the actual current that the pixels draw because it is often significantly lower than 0.0555 amps. Note that if you're using pixel strips or modules with three RGB LEDs per pixel, you're still limited by the total number of pixels, not the number of LEDs because the three are arranged in series within each pixel and the same current flows through all of them.

I also suggest choosing the higher quality RSP power supply if you can get it at a similar price. This would apply if you plan to have a large display with multiple power supplies.
Could you explain the differences between the LRS and the RSP? I've looked at the sheets and other then a 3% better efficiency for the RPS they are near identical. The does RPS cost about twice what the LRS does for roughly the same output. I compared the LRS-350-12 vs the RPS- 320-12 based off of what was found on amazon.

I'm new so have yet to figure everything out and did notice the RPS was used behind the scenes for some light shows also. Just thought it was a good place and time to ask about the differences from more experienced people.

Thanks.
Dean