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Topic: Double checking my power distribution for NeoPixel strips (Read 816 times) previous topic - next topic

elemenohpee

Attached is a diagram of my setup, hopefully it's clear. The strips work for a little bit running strandtest, then start blinking random pixels and colors, then stop working. The last time I think I even saw some smoke, but I unplugged it really quickly so I didn't see where it was coming from. I've read that the random pixels coming on can be an issue with the strips not being grounded to the Arduino, but I've done that, and I've double checked all the connections. Do I have the wiring for the power distribution correct? Is there something else that I'm doing wrong? Help! Thank you in advance!

Grumpy_Mike

I would add a seriese resistor in the data signal from the Arduino 220 to 510R. I would also connect the power and ground at the end of the strips as well as the beginning.

You should have no smoke with that unless the power supply is faulty or going a bit nuts because the large capacitor is not large enough. Check the output voltage under load, preferably with an oscilloscope to see if it is oscillating.

elemenohpee

Oops, I forgot to include it in the diagram, but the recommended resistor is in there too.

When you say connect the power and ground at the end, you mean wire all three powers together and all three grounds together, right? Connect those back to the power supply, or no?


Grumpy_Mike

Yes wire the power and ground to both ends of the strips.

CrossRoads

Maybe in the middle of the strips too, if they are long. How many LEDs are in each one?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

elemenohpee

48 LEDs per strip.

Could you help me understand what the issue was with my original setup and what connecting to both ends is accomplishing?

Grumpy_Mike

It makes for a better power distribution, that is it lowers the resistance of the wires so you do not lose so much voltage when large currents flow. The resistance of the foil tracks on a PCB are quite high when compared to normal wire.

elemenohpee

If voltage drop were the issue, wouldn't I just see some color shifting towards the end of the strip? Or could that also cause random LEDs to come on?

Grumpy_Mike

If voltage drop were the issue, wouldn't I just see some color shifting towards the end of the strip?
No.

Do you want help or not?

elemenohpee

I'm just trying to understand rather than follow instructions. I appreciate you taking the time to help.

Grumpy_Mike

Electronics work correctly when supplied with the voltage they were designed for. Anything else is bad. You asked if your circuit had the power distribution right. I offered ways to improve it. I don't see why this should take ten replies.

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