I am hearing a high-pitched noise originating from the PixelBlaze that seems to vary depending upon how “busy” the PixelBlaze is. I had not noticed this before, probably because I was testing it in an environment that had many cooling fans in PCs. Is there anything that can be done? Thanks…
Capacitors can have a piezoelectric effect, and can “ring” when excited. The only capacitors on a Pixelblaze are for stabilizing the power, so my guess is that your power supply is having some issues, causing oscillations on the power line, which are causing ringing on the capacitors. You might be running too many LEDs, overloading the power supply, or its internal power filtering capacitors may have failed.
I would try removing the LEDs and powering pixelblaze from a different power supply, like USB from a computer, and see if the noise goes away.
Thanks for the ideas! I knew that capacitors could do that, and I suspected the power supply of being noisy, so I changed from the power brick I was using (and had purchased just for this project) back to a nice USB “wall wart” and the noise vanished! I’m more than a bit annoyed as this is an Adafruit power brick they sell especially for working with LEDs. I have another new power brick around (from a different source) and might try using it later this eve.
@wizard - your diagnosis of the power supply was 100% correct. I knew that powering via USB worked fine with no noise, but powering from a “brick”-type 5V 10A power supply from Adafruit was the culprit. Too bad it is too old to return.
I had a different make/model “brick”-type 5V 15A power supply sitting around which worked just fine - I wish I could recall where I got this one and its two siblings from so that I could recommend them. 15A is complete overkill for this small 3x3 matrix of your 8x8 LED Matrix (SK6812) boards. I purchased these power supplies for other projects including powering the 4 meter spool of 60/m SK6812 (WS2812) RGBW LEDs that I got from you about a year ago…
Glad to hear you identified the problem and have something that works!
Sorry to hear the Adafruit power supply isn’t working right anymore. It never hurts to go a bit larger on the power supply that necessary.