LED strip power?

[ShreddinPB]

Hey guys, so I am helping a friend with some LED strips, we are using the addressable 5V ws2812B strips. We are going to be running enough that we will need about 28 amps total, 7 strips of about 4amps per. They have 12V that they have, so I need to step down to 5V. I found this guy, can I just use 2 of them?
http://www.amazon.com/SMAKN-Converter-P ... +step+down
One powering one half and the other, well the other half? Since they will be using the same ground, the signal wire from the arduino should be fine?
Forgot to mention I am using an Arduino uno to sequence the light show.

[Popeye]

I don't see why your power supply idea wouldn't work but be careful how you connect the arduino, I doubt you can easily sync the two power supplies. I am curious about your numbers though. At full brightness each LED pulls 50MA, a 30 LED strip pulls 1.5A. If you are using an Arduino you obviously aren't running at full brightness or having all the LED's on at the same time. You could calculate the brightness level and the on/off time and use it to factor the power draw. Or perhaps you have already done this?
Most multimeters have a DC amp function. You might want to hook up half of your LED's to one of these power supplys and the arduino and check the draw. If the reading is jumping around use the bar graph or analog function and use the peak numbers.

Good luck and post some pictures when you get it working.

[Gazmatron]

I'm not clear if you are planning to, but you can't run that type of DC-DC converter in parallel - the voltages will not be identical and thus the one regulating at the higher voltage will take all the load.

However, the arduino, as you say, will still need a common ground for the data signal. You could try running the arduino using a separate (isolated) power supply, but I've had issues experimenting with this type of arrangement before and the data signal got screwed up.

Fyi, this is the DC-DC converter I've used before - looks similar to yours, though a bit more powerful at 150w
http://www.ebay.com/itm/DC-DC-Converter ... 0764296826

A safer bet would be to lower your power draw to avoid needing two regulators. You don't need to run 5050's anywhere near full power to get good brightness. I run mine at 30% and it's still blinding

[ShreddinPB]

I don't see why your power supply idea wouldn't work but be careful how you connect the arduino, I doubt you can easily sync the two power supplies. I am curious about your numbers though. At full brightness each LED pulls 50MA, a 30 LED strip pulls 1.5A. If you are using an Arduino you obviously aren't running at full brightness or having all the LED's on at the same time. You could calculate the brightness level and the on/off time and use it to factor the power draw. Or perhaps you have already done this?
Most multimeters have a DC amp function. You might want to hook up half of your LED's to one of these power supplys and the arduino and check the draw. If the reading is jumping around use the bar graph or analog function and use the peak numbers.

Good luck and post some pictures when you get it working.

Yeah, we calculated, to be safe, we wanted 4A per string, and we have 7 strings.

[ShreddinPB]

I'm not clear if you are planning to, but you can't run that type of DC-DC converter in parallel - the voltages will not be identical and thus the one regulating at the higher voltage will take all the load.

However, the arduino, as you say, will still need a common ground for the data signal. You could try running the arduino using a separate (isolated) power supply, but I've had issues experimenting with this type of arrangement before and the data signal got screwed up.

Fyi, this is the DC-DC converter I've used before - looks similar to yours, though a bit more powerful at 150w
http://www.ebay.com/itm/DC-DC-Converter ... 0764296826

A safer bet would be to lower your power draw to avoid needing two regulators. You don't need to run 5050's anywhere near full power to get good brightness. I run mine at 30% and it's still blinding

Thats what I thought.. I wasnt sure they could be run in parallel since they are not isolated.
I am going to look for that guy local as that one probably wouldnt get here in time.

[maladroit]

Two or more supplies will work fine if you split the system. That means if two supplies are connected to the same strip, you'll have to break the 5V line at some point so the supplies aren't connected together.

You will of course connect all grounds together.

Controlling 450+ pixels from a single Arduino is likely to be your biggest problem, you might run out of memory or not have enough CPU to do smooth patterns. I suggest switching to a Teensy 3.1.

[ShreddinPB]

Two or more supplies will work fine if you split the system. That means if two supplies are connected to the same strip, you'll have to break the 5V line at some point so the supplies aren't connected together.

You will of course connect all grounds together.

Controlling 450+ pixels from a single Arduino is likely to be your biggest problem, you might run out of memory or not have enough CPU to do smooth patterns. I suggest switching to a Teensy 3.1.

I am a little lost in the "break the 5v line"
If I use 2 of the 20A ones, I can power half off one, rest off the other, and the arduino can pull its power from the one only using 3 strips?
If a regular arduino cant handle that many, I have a mega I can throw at the project, that should be enough right? its a 2560

[ShreddinPB]

Excuse the poor photochop.. but I think it gets the point across.
They are WS2812B strips, they will all go in unison.
Would this work?

ledStripHookup.jpg

As a side note, power and signal would actually be going in the same side.. just did that for ease of view

[Gazmatron]

I've experimented with a very similar configuration in the past and was unable to get a clean signal. I wasn’t using arduino, but the power config was the same.

WS2812B seems more sensitive than earlier generations of addressable strip. My knowledge of electronics isn't sufficient to explain why the interaction of separate regulated power sources using a common ground wouldn't work in my scenario. However, the only way I was able to resolve it was to use two separate controllers so there was no common ground for either set of strips or the controllers. I.e. the data signal for each group of strips was completely isolated.

I also thought what you suggest would work in my initial design. It may be that there was something unique to my configuration that I missed. One possibility is that the wiring in my system needs to be very tightly packed, so perhaps there could have been some EMI etc. If you are running the wiring for each set of strips in different directions perhaps that would help.

I'm just letting you know that although it seems ok in theory it didn't work for me in practice (in my particular setup), and to be aware of how sensitive WS2812B is to signal quality. If you do go this route, as always, make sure you give yourself a bit of time for testing/plan-b!

To give you an idea on power, I run just over 4000 LEDs using WS2812B. At 30% brightness I can keep the draw under 10A (often 4A) so long as I don't use a pattern that drives all the LEDs simultaneously.

How many LEDs are you looking to use?
Good luck with it!

[ShreddinPB]

I've experimented with a very similar configuration in the past and was unable to get a clean signal. I wasn’t using arduino, but the power config was the same.

WS2812B seems more sensitive than earlier generations of addressable strip. My knowledge of electronics isn't sufficient to explain why the interaction of separate regulated power sources using a common ground wouldn't work in my scenario. However, the only way I was able to resolve it was to use two separate controllers so there was no common ground for either set of strips or the controllers. I.e. the data signal for each group of strips was completely isolated.

I also thought what you suggest would work in my initial design. It may be that there was something unique to my configuration that I missed. One possibility is that the wiring in my system needs to be very tightly packed, so perhaps there could have been some EMI etc. If you are running the wiring for each set of strips in different directions perhaps that would help.

I'm just letting you know that although it seems ok in theory it didn't work for me in practice (in my particular setup), and to be aware of how sensitive WS2812B is to signal quality. If you do go this route, as always, make sure you give yourself a bit of time for testing/plan-b!

To give you an idea on power, I run just over 4000 LEDs using WS2812B. At 30% brightness I can keep the draw under 10A (often 4A) so long as I don't use a pattern that drives all the LEDs simultaneously.

How many LEDs are you looking to use?
Good luck with it!

Yeah, I thought it was questionable.
We are going to try to use one 20A one for now, since all the lights will not be on steady at all times.
We will also bring a inverter and a computer PSU as a backup