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Topic: Why does PWM creates noise? (Read 753 times) previous topic - next topic

Docedison

Normally I'd say isolate them... but unless your on board regulator (Arduino) is running hot... Just make sure of the grounds... try to use a star topology where Every Ground goes to one Common Point. Never Never daisy chain grounds or the Positive Supply runs. All wires including PC boards have Both resistance and worse inductance both of which will increase as your project changes and both of which are 1/2 of the primary offenders for producing noise. Obviously the other half is the various supply voltages however it is Very Common to think that ground is Ground. Short wiring and plenty of bypass caps... make the job work well.

Bob
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"The solution of every problem is another problem." -Johann Wolfgang von Goethe
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Nick Gammon

I think you can change the prescaler so that the modulation is at a higher frequency. The noise you hear is probably harmonics from the square wave. Just shove it out of human hearing range.

Docedison

Great Idea, just move them out of the passband of your amp so they don't get amplified. Even though you can't hear it doesn't mean that the amp can't amp it and that is wasted power and a possible source of distortion if any of the amp sources has any power in that range they might mix and cause noise. 

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Nick Gammon

Quote
Great Idea,  ...


Or not?

However audio amplifiers probably don't amplify in the megaherz range.

However that was just a suggestion. If you can eliminate the noise, all the better.

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