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Noise on guitar from Neopixels
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Noise on guitar from Neopixels

by Yags on Tue Jan 09, 2018 3:10 pm

I'm in a band, and have added some neopixel strips to my costume for shows. Problem is, whenever I turn on the LEDs, there is a loud hum that comes from my electric guitar! The strip and arduino are powered by a USB battery pack, and are not electrically connected to the guitar in any way. It happens even when the LEDs are a foot or more away from the guitar.

I'm thinking it's some magnetic fields set up by the cycle time of the LEDs, that's registering on the guitar pickups. Any ideas for how to stop it???

Yags
 
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Re: Noise on guitar from Neopixels

by franklin97355 on Tue Jan 09, 2018 3:23 pm

You could test it by powering it from a battery pack of 4 AA NiMH cells and see if the noise is coming from the power pack or the Arduino/pixels.

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Re: Noise on guitar from Neopixels

by adafruit_support_bill on Tue Jan 09, 2018 3:38 pm

You have two possible sources of noise there: The USB power pack probably has a voltage boost circuit inside. These use high-frequency switching to boost the voltage and the switching noise can couple inductively with nearby circuits.

The Neopixels themselves use PWM switching to control power to the LEDs. The power and ground traces on the strip can act as antennae to broadcast this switching noise to sensitive circuits (like guitar pickups) nearby.

As Franklin suggests, swapping the USB pack for an AA pack will help determine if the USB pack is a noise source.

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Re: Noise on guitar from Neopixels

by KJEN on Fri Jan 12, 2018 8:17 pm

Would a common ground/earth be a solution?

Sorry to but in =)

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Re: Noise on guitar from Neopixels

by wwaver on Thu Jan 18, 2018 12:21 pm

Just curious. What type of guitar are you using and what type of Pickups?

Do you have active pickups or non-active?

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Please be positive and constructive with your questions and comments.