Need Power Supply Help from the guru's.....(you know who you are)

[ezimnow]

I know nothing about Power Supplies or current draw and that's why I posted this topic. The post I put in here was from Aus Christmas lighting and what someone responded to me on this same topic. It certainly can be a bit confusing. I'm just reaching out to make sure I understand what everyone who uses WS2811 pixels is doing in this regard.

 

Thanks

 

Eddie Z

[plasmadrive]

Crazy,

 

I would be they just have a typo.  the wattage per string seems correct but the single pixel wattage is surely not. 

 

Max,

ezimnow is right in the respect that in reality when run a full strip with power at only one end, the drop does indeed lower the overall current draw.   So reality vs. spec.. nothing more me thinks..

[Max-Paul]

Plasma,

 

But your missing my point. When designing one should always go with a number that will fudge in a little more (over engineer). So ya I will concede that not each and every node/pixel is going to draw 60mA IF only injecting from one end. But what if he runs more than one strip and injects at all ends? With my way of figuring it, he will have it covered with my numbers. "KISS" engineering is so much simpler. Kind of like putting in the adapter when playing with E1.31, than to turn off the RS485 network. Then in the fall individual forgets that they turned off the network and has to be trouble shot. My techic is so much simpler and saves time in the long run. If you engineer for the bare minimum and then have to trouble shoot a problem that was created by using the bare minimum. I call it padding the requirements.

[plasmadrive]

Plasma,

 

But your missing my point. When designing one should always go with a number that will fudge in a little more (over engineer). So ya I will concede that not each and every node/pixel is going to draw 60mA IF only injecting from one end. But what if he runs more than one strip and injects at all ends? With my way of figuring it, he will have it covered with my numbers. "KISS" engineering is so much simpler. Kind of like putting in the adapter when playing with E1.31, than to turn off the RS485 network. Then in the fall individual forgets that they turned off the network and has to be trouble shot. My techic is so much simpler and saves time in the long run. If you engineer for the bare minimum and then have to trouble shoot a problem that was created by using the bare minimum. I call it padding the requirements.

Abso-friggin-lutley!   Design for worst case.  You and I are not in disagreement there.. I was just thinking out loud about why ezimnow said what he did. 

 

I still don't agree with the adapter thing though.. Users should learn why things work and why they don't work.. Knowing that they don't need that adapter (dongle) for E1.31 I think is important for them to learn.  Your way is indeed less reliant on someone actually learning what it takes to make it work.. I agree.. but we should encourage the learning.. no?

[Max-Paul]

I agree that we should encourage people to learn. But at times I give up on the sheeple learning. They seem to be in a rush to get things working and be damned the why of it. Hobbies if done right are not all about the end, but the journey to get to the end and to learn something new. I suppose being 55 I am from the old school. Now days it is all about the end product and damn learning anything.

 

Plasma I think we both are from the old school. Just take different angles to get to the same end result. I can see you are a hobbiest as I am. Like the challenge of building.

[Crazydave]

Crazy,

 

I really do not know how to answer what the site says. But I am 55, and have been doing electronics for the past 40 years. Ohms law is just that a law. And PIE has never failed me in pure D.C. circuits. So to find power, one multiply voltage by current (P=I*E). And we know that the 5050 RGB module is rated for 20mA per LED. Remember we are looking for max power required of the power supply. So, thus I have all 3 LEDs turned on and drawing max current of 60mA.  So, using the above formula we take 12 * .06A = .72W * 50 = 36w per string.

 

Sorry to all of my friends. But all other answers are wrong.  I do not know where ezimnow comes up with this 55 or 50mA. Now that might be where you run it or after the voltage drop it might end up there. But I am going strickly by what it is rated for. Not some magical might be cause of this or that variable.

 

I understand that Amps * Voltage = Wattage

I was just trying to show that the specs given by holiday coro didn't make sense and therefore probably not the most reliable. But I'm not too trusting of ray wu specs either. I just wish we had some more definitive answer on the current draws of pixels (both 5v and 12v). I must have gotten confused somewhere.

 

If it is  common knowledge that a 12v  AND a 5V 5050 RGB both draws 60mA at full white, then I'll defer to that. 

 

 

I've emailed holidaycoro to update their specs.

Sorry about the confusion.

Edited June 20, 2014 by Crazydave

[Scott Cockroft]

Do 5050 strip type LEDs and 12mm bullet style LEDs draw the same current? Is it fairly standard that both are speced at 60mA all white?

I've seen info on the bullet style pixels rated at 60mA. However, when I used a meter to measure current draw on a full string of 50 5 volt bullet style pixels it was much less than 3 amps even at full white.

I don't have any knowledge about the 5050 strip type LEDs current draw.

[Max-Paul]

This could be an interesting conversation with your findings Scott. But please dont just say it was much less than 3 amps. What did you measure? Was it like 2 amps? What is "much less"?

 

And I could only guess what the bullet RGB LEDs draw. Many years ago when I was a teen. The most common current draw was more like 10mA at about 1.2volts. Now that was for a common red LED. We didn't even have blue LEDs yet. A few years later they came out with a blue LED and I was about 19 or 20 years old. Now days we LEDs that go all the way up to what, 50 Watts at 12 volts, or about 4 amps.

 

With google or your favorite web search engine, one should be able to put some info like LED 5050 and come up with the spec sheet that tells you the max current rating. Find out what LED those bullets are Scott and do a search on them. Then select a few of those web sites and find a spec sheet.

[Crazydave]

I found this spec sheet:

http://www.superbrightleds.com/moreinfo/component-leds/rgb-5050-smd-led-120-degree-viewing-angle/322/

[Max-Paul]

Ok, as you noticed Crazydave. There was a continuous forward current, which was 3X20mA. And then there is the peak forward current rated at 3 x 100mA. But this would be like swipeing a wire across a terminal.

 

As you and others can see. When I call out 60mA as a white aka full on load. I am giving some good poop.