HC-05 and annoying pulsation

[vajo]

I'm using Arduino Uno + Hc05 within the guitar effects chain that is between guitar and amplifier. It happens that the blinking of the LED on HC05 is also transmitted to the output of the loudspeaker from which comes an annoying pulsation that I would like to eliminate.

In fact, if I power off the HC-05, the bluetooth switches off, the LED goes off and the pulse disappears.

I tried to put a 100 uF capacitor in parallel to the power of the HC05 but I did not solve anything and the pulsation remains.

Thanks !

 

[kellys_eye]

Remove the LED

 

[vajo]

I do not know if it can be taken off, it's tiny smd...and i need to see it flash in the moment of Arduino programming because I know I have to turn it off

 

[kellys_eye]

Further power supply capacitive decoupling would probably help but you'd need to get it close to the power pins of the device driving the LED and/or the LED itself. This would likely necessitate the use of additional surface-mount devices and if you're reluctant/incapable of removing the LED the adding such parts is also likely to be impossible.

 

[vajo]

I desolded the LED but the pulse remained.