Trouble getting enough power to LED strip

[Schlogdawg]

Hi all,
My project is trying to get an adafruit neopixel strip (9 leds) to light up red. I have tested this strip using jumper cables connected to the arduino uno r3 and the leds work as expected. I then soldered about 12 feet of 16 gauge wire in between the arduino and the leds and now the led strip is lighting up green.
I read on another forum that the voltage drop across the wire is too much and the red requires more power and thus doesnt get through. In that same forum it recommended to use a lower data rate. Originally I was using the NEO_KHZ800 but dropping it to NEO_KHZ400 caused the LEDs to turn white.

Attached a pic of the basic setup.

Im assuming I need to somehow increase the voltage getting to the LEDs?

I dont know if this issue is against the 5V going to the LEDs, or the data out PIN from the arduino. Is this something I could use a pull-up resistor with? If so, Im not sure how to implement it.

Thanks in advance!!

 

[Bluejets]

Cannot see your pdf for some reason.... maybe it's my phone. However do you realise Arduino pin is only good for around 20ma?

 

[Schlogdawg]

Cannot see your pdf for some reason.... maybe it's my phone. However do you realise Arduino pin is only good for around 20ma?

Hrmm, it works pulling it up on my computer... But that would make sense why Im having issues sending data across the long lines, correct?

My knowledge around electronics is somewhat basic. But reading:
https://forum.automationdirect.com/.../897-0-20ma-and-4-20ma-signals-vs-wire-length

It looks like in my case theres not even an ohm of resistance across the ~12 feet of wire. So the voltage drop would be minor.

If the voltage drop is negligible and resistance is negligible wouldn't the current at 20mA be consistent across the entire wire length? Thus, there not being an issue at the LED strip?

 

[BobK]

16 gauge wire is more like overkill for the current required by 9 RGB LEDs (max 1/2 A).

The problem is probably the signal. Try terminating the data line at the LED strip with a 100Ω resistor to ground to make it less susceptible to interference.

Bob

 

[Schlogdawg]

16 gauge wire is more like overkill for the current required by 9 RGB LEDs (max 1/2 A).

The problem is probably the signal. Try terminating the data line at the LED strip with a 100Ω resistor to ground to make it less susceptible to interference.

Bob

You were spot on! That cleared things up. What about more wire adds interference to the signal?

 

[(*steve*)]

There is also a limit on how much current you can draw from the 5V of the Arduino.

What is powering the Arduino? What voltage?

 

[Schlogdawg]

There is also a limit on how much current you can draw from the 5V of the Arduino.

What is powering the Arduino? What voltage?

Its powered via the usb jack which I believe is 5V.

Eventually it will be powered through the barrel jack at about 12V, probably more like 11.5 though. I think theres a voltage regulator on the barrel jack that drops it down to 5V though.

 

[(*steve*)]

Check the specs of your Arduino carefully. Your USB port is possibly limited to 500mA, the regulator on the Arduino can almost certainly supply LESS. Remember that both also have to power stuff other than your LED strip.

What current is rewired by your LED strip? Can you point us to a description of this strip?

 

[BobK]

You were spot on! That cleared things up. What about more wire adds interference to the signal?

A long wire is an antenna. It picks up RF noise, varying the voltage at the end of the wire. But that voltage cannot supply much current, so a low resistance at the end will knock it down.

Bob

 

[Schlogdawg]

Check the specs of your Arduino carefully. Your USB port is possibly limited to 500mA, the regulator on the Arduino can almost certainly supply LESS. Remember that both also have to power stuff other than your LED strip.

What current is rewired by your LED strip? Can you point us to a description of this strip?

Okay, thats something I'll have to look into.

If I'm reading it correctly, it looks like 20mA.
https://cdn.sparkfun.com/datasheets/Components/LED/WS2812.pdf

 

[Schlogdawg]

A long wire is an antenna. It picks up RF noise, varying the voltage at the end of the wire. But that voltage cannot supply much current, so a low resistance at the end will knock it down.

Bob

Ahh okay great, thats good to know. Thanks for the information.

 

[CDRIVE]

A long wire is an antenna. It picks up RF noise, varying the voltage at the end of the wire. But that voltage cannot supply much current, so a low resistance at the end will knock it down.

Bob

Ahh okay great, thats good to know. Thanks for the information.

You were fortunate to find EP. While Automation Direct is undoubtedly the most popular manufacturer of HSM VFD's, I doubt that their forum is geared for the level of electronics knowledge found here. If I ever get the bug to replace the original motor in my SB Heavy10 with a Baldor 3PH it will be controlled by an Automation Direct VFD. It's the most bang for the buck!

Blue Chips!
Chris

 

[(*steve*)]

Okay, thats something I'll have to look into.

If I'm reading it correctly, it looks like 20mA.
https://cdn.sparkfun.com/datasheets/Components/LED/WS2812.pdf

Each package can draw up to 60mA, 20mA for each of red, green, and blue.

A string of 9 of them can draw up to 540mA.

But what I was referring to was the amount of current the Arduino can supply from it's 5V output. It's likely to be far less than 540mA