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Topic: tone() is distorted while other pins have high power output (Read 481 times) previous topic - next topic

whirligig231

Hello,

I'm currently using my Uno R3 to power a neopixel strip and a speaker. The neopixels draw a large amount of current, and I'm finding that while the strip is powered (i.e. when the LEDs are showing colors and not black), any tones played through the speaker using tone() come out sounding distorted. In addition, sometimes there is a clicking noise when the neopixels are shining brightly even if no tone is being output to the speaker.

I suspect the issue here is that the voltage across the output pins is being intermittently brought down from 5V slightly by the high current draw, and since the speaker is an analog device this change is audible (there's not a visible change in brightness on the LEDs though). Is there anything I can do to mitigate this issue?

larryd

No technical PMs.
The last thing you did is where you should start looking.

whirligig231

I understand that the neopixels are supposed to have a separate power supply, but I've had no trouble with using the Arduino itself provided I don't make them too bright. I'm guessing that there's no other way to stabilize the voltage on the other pins though?

DVDdoug

Quote
but I've had no trouble with using the Arduino itself provided I don't make them too bright.
Dimming with PWM reduces the average  current, but it does not reduce the peak current.  The amount of current you can get out of the Arduino's 5V supply depends on how much voltage you are dropping across the voltage regulator, and the temperature.

And of course, the amount of (peak) current you are drawing depends on the number of LEDs that are on at any instant.

Grumpy_Mike

Quote
but I've had no trouble with using the Arduino itself provided I don't make them too bright
Which is another way of saying "I am having trouble when the LEDs are bright".

The lack of an adequate power supply and large smoothing is the cause of this problem. Just because on low brightness you have not noticed any problems does not mean you do not have any. In fact you do have problems which is why you started the thread in the first place.

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