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DIY Pocket PiGRRL Raspberry Pi w Pi Zero
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DIY Pocket PiGRRL Raspberry Pi w Pi Zero

by vanwilder on Fri Aug 16, 2019 1:56 pm

Hi everyone,

I'm looking forward to being a part of the community.
And I was wondering if anyone can help with an issue I'm experiencing.
Recently I bought Pigrrl pocket kit.
And I really enjoyed building it.
For my build, I used Raspberry Pi Zero W.
For audio, I used this guide ... io-outputs .
I put in the RC filter and connected it to GPIO 19 and then to the amp.
Audio works but I am getting this background sound that sounds like flying saucer.
I tried changing the audio pin from GPIO 19 to GPIO 18 with the same result.
Also, I moved button UP form GPIO 18 to GPIO 26.
The sound starts as soon as the display starts showing text.
I tried playing sounds with display disconnected and the sound disappears in that case.
I also cut the GPIO 18 pin so that it does not go through the display board, but sadly that did not help either.
Currently, I am without ideas.

If you have any suggestions it would be much appreciated.

Thank you in advance.

Best regards,

Posts: 5
Joined: Sat Aug 10, 2019 8:31 pm

Re: DIY Pocket PiGRRL Raspberry Pi w Pi Zero

by adafruit_support_mike on Fri Aug 16, 2019 11:23 pm

From your description, it sounds like the data signals are creating a small amount of signal in the battery. Anything with current flowing through it acts like an antenna, and fast-moving signals create radio waves strong enough to pick up a few centimeters away.

Adding a shield will probably improve things. Start with a piece of copper wire a few inches long, and strip about 1" of insulation off the end. Cut a piece of aluminum foil a bit larger than the LiPo, lay the bare wire on the foil, then cover the whole thing with painter's tape (or any other self-adhesive sheet material). Then flip the whole thing over and cover the other side of the foil with another piece of tape. When you're done, you should have a package of tape that completely covers the foil, and has the insulated end of the wire sticking out.

Solder the free end of the wire to one of the PowerBoost's GND pins. That will hold the foil at 0V, which makes it act like a mirror for radio signals.

Put the shield between the LiPo and the RasPi, and see if that helps with the noise.

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Please be positive and constructive with your questions and comments.