NeoPixel strip powered by Arduino Uno not staying on

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BBennett
 
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NeoPixel strip powered by Arduino Uno not staying on

Post by BBennett »

Hello, I'm trying to power a small strip of 12 NeoPixels with an Arduino Uno and having mixed luck. I assumed the small number of pixels in the strip would allow for me to power directly off the Uno without a secondary power supply. Is this safe to say?

Everything was working just find with a momentary switch to change color modes but then a problem started. The switch will cycle to the first color which will stay on for one second and then cycle back to the default mode (all LEDs off). The time that the LEDs stay in the second mode is constant and will not cycle beyond the second mode, just return to the first mode (all LEDs off).

I have a resistor connected to the data pin but no capacitor connected to the power pins since I'm connected directly to the Uno. Am I taking too much for granted with the Uno supplying power? What would be the max number of neopixels to power off the Uno without sacrificing brightness?

Thanks!

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Re: NeoPixel strip powered by Arduino Uno not staying on

Post by adafruit_support_bill »

What would be the max number of neopixels to power off the Uno
That depends on what you average pixel intensity is and how you are powering the Arduino.

12 pixels at full intensity is about 720mA. That is enough to overload a USB power supply or overheat the on-board regulator. If powering from an external supply, higher supply voltages mean less current capability for powering pixels.

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BBennett
 
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Re: NeoPixel strip powered by Arduino Uno not staying on

Post by BBennett »

I was powering with 4 AA rechargeable batteries. I tried a 9V and that seems to have fixed the issue. Do I need to worry about overloading the Uno?

Thanks!

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Re: NeoPixel strip powered by Arduino Uno not staying on

Post by adafruit_support_bill »

I was powering with 4 AA rechargeable batteries. I tried a 9V and that seems to have fixed the issue. Do I need to worry about overloading the Uno?
NiMH rechargeables are usually pretty good into high-current loads. Were they freshly charged?
With a 9v supply and 12 pixels, you be OK with 12 pixels as long as you don't try to drive the pixels at full-intensity white for extended periods of time.

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BBennett
 
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Re: NeoPixel strip powered by Arduino Uno not staying on

Post by BBennett »

I'm trying to get a few hours out of the pixels and would prefer to use rechargeable AA if possible. I'll try lowering the brightness a bit and see if that works. Thanks!

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hdtbill
 
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Re: NeoPixel strip powered by Arduino Uno not staying on

Post by hdtbill »

I had the same problem last nite, turned out I forgot to make the batt-to-Arduino ground connection. So the ring worked but very poorly. Now it's looking great on the Standtest. I do have the resistor and the capacitor. Be sure to check out the wiring diagram which is given in the Arduino section of the Uberguide.

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