Hey guys, I’ve got 10 1 meter 60 LED strips with WS2812B LEDS. Would anyone have a clue why I could be experiencing flickering on my last 4 strips. If there are unlit or dim LEDS Random LEDS will flash random colors at random intervals. If they are all lit and bright then they function as expected.
Without seeing or understanding how you have the strips connected, my best guess is a power problem.
How have you connected power to the strips?
My recommendation is to inject power at both ends of each meter of the strip. . You can test the power issue by attaching power to the end of the strip too.
@Michael_Sharnet here is a quick sketch of my wiring. the lines connecting the strips represent the data lines. Let me know if its to messy to decipher and I’ll make a better sketch when i get home: http://oi61.tinypic.com/2ro5lqh.jpg
I’ll give injecting power at the end of each strip a try, could you possibly elaborate on the reasoning behind that.
Power problems are common with 5v LED strips. The voltage drop on 5 meters is about 30%. So that means the starting LEDs get 5v and the LEDs at the far end get 3.33v or less. And one way around that is to connect power (and ground) at multiple places along the strip.
I’ve got 10 1 meter strips though and each strip has its own 5v and ground connection
What wire gauge and length are you using from the power supply to the strips? Does each strip connect directly back to the power supply or multiple wires?
Also is have you considered grounding the data line at the far end (I put a 20Kohm resistor to ground on the the far end data line on my longer installations).
I’m using a computer power supply, I’m not sure what gauge those wires are but they’re less than a foot long. I’ve soldered about 4 feet of 22 gauge wire to them to use as a power strip. The led strips have short wires comming off of them and are connected directly to the 22 gauge wire.
As far as grounding the data line you mean only the one on the last strip, right?
Yes the resistor to ground on the data line is just the very last LED.
Ok you have 10 X 60 leds = 600 @ 5V DC rated for 0.06 amp per led based on 20mA - red, 20mA green, and 20mA blue (please confirm my numbers).
So that means when all of your leds are on full white the 22 gauge wire needs to support 36 amps. And a single pair of 22 awg wires will not support 36 amps over 4 feet.
The voltage drop of four feet long, 22 awg wire running 18 amps is over 40%. That means your 5v DC at the start of the wire is down to 3 volts at the end of the wire. Remember these LEDs start doing funny things with less than 3.3 volts.
AWG 22 gauge is rated for 7 amps max for inside cabinet wiring.
Is your power supply capable of providing 36 amps on the 5V DC rails?
My calculations do not take into consideration the additional voltage drop that occurs down each strip which could be why you are seeing the problems as you get farther away from the power supply.
My recommendations:
Confirm your power supply is up to the task (I would want it to be able to handle 18 amp) you can argue for 12 amps if your brightness settings are low enough.
If available, consider using more than one 5v rail from your power supply. (Remember to bring everything to a common ground if you use more than one rail on the power supply).
Use 16awg (or better) as your power rail or use multiple smaller power rails. (16awg is rated for 22 amps max in cabinet wiring)
Continue to using 22awg to wire from the power rails to the strips
This is the power supply I’m using:http://www.newegg.com/Product/Product.aspx?Item=N82E16817170016
According to the package it can handle 36 amps on the 5v rail. I cut about 2 feet off of my current power strips and that didnt fix my problem so I just ordered some 14 awg wire. I am using 2 separate wires to power 5 strips each however, they are connected to the same 5v rail since there is only one. For future reference is there any reason not to use a smaller gauge wire if I have it available.
Thank you for your help.
@Aleks_Azen , check the voltage at the end of your 22 gauge “power bus”. My guess is that’s not nearly thick enough.
check power and grounding. your controller should share the same ground as your LED.
Your power supply looks like it should be able to handle the load as long as you watch the brightness when going with full white.
To determine the base size of wire, I use an AWG ampacity chart - here is one: https://www.eol.ucar.edu/rtf/facilities/isff/LOCAL_access_only/Wire_Size.htm
And to determine if my base wire selection is large enough, I use a voltage drop calculator like this one: http://www.calculator.net/voltage-drop-calculator.html
I just stripped the very end of my power strip and measured voltage there and I was getting 4.9 volts on my longer one and 4.95 on the shorter one. Maybe wire gauge isnt my problem?
@Aleks_Azen When you measure the voltage are the LEDs connected and running or is this reading without the LEDs?
@Michael_Sharnet I was a bit grogy this morning and yes I did measure them without the LEDS on. Stupid me, with them on its 3 volts at the end
@Aleks_Azen I ran into multiple problems trying to power LEDs when I first started. I had to bring out my old college electronics book and review voltage drop, ohms law and such (its been 25 years). This group is a great place to get help and share your knowledge. I learn from every post I read.
@Michael_Sharnet quick question, do I need to rewire the ground strip or is that fine with 22 awg
@Aleks_Azen Yes, you need the same gauge wire on the positive and negative for your power leads. (The same amount of current flows on both wires).