Arduino humming noise

[Grumpy_Mike]

@theboot

said toggled to reference that it will be switching between high and low for the duration of the second

Yes but you are wrong about that.
Take this simple code:-

void setup() {
analogWrite(11, 255);
}

void loop() {
}

This is the waveform it produces on an oscilloscope:-

Do you see any form of toggling

at all?
The answer is no, it doesn't toggle.

If you change the code to:-

void setup() {
analogWrite(11, 128);
}

void loop() {
}

Then you see this, look it is toggling.

So to claim the output toggles with a value of 255 IS 100% WRONG

@theboot

So 255 the pin will be toggled high the whole second.

[theboot]

But when you set it to 255, how does it get to 255, it toggles to 255

But yes a poor choice of words for 255.

Lets say 254 then it will toggle on and off with a duty cycle of 99.6%

[asaroli]

After reading these answers it seems like most people agree it is just the sound of the PWM as the humming disappears when i disconnect the motors

[asaroli]

and now that I think about it the humming only started when i added the pwm feature

[paulpaulson]

"What shall we do with the ........."

[theboot]

@asaroli

and now that I think about it the humming only started when i added the pwm feature

So change the frequency of the pwm pins to a higher frequency. See this link

https://domoticx.com/arduino-pwm-frequency-and-timers/

[TomGeorge]

Hi,
This is one of two projects in the forum with basically the same problem AND using 9V PP3 batteries.

Buzzing sound when low Arduino PWM used

Hello there. At the moment I have been testing a motor with relay attached to it. I use analogWrite() function together with PWM pins both for Arduino and I298N relay to control the speed of the motor. The problem is that when the argument (0-255) is less than 100, sometimes, I hear a continous buzzing sound (motor stops rotating) which disappears when I stop the motor or pass some higher values to analogWrite() function. Thus, I can't assign very slow speed for the motor. Would you, please, tel…

Tom..