Halloween talking skull with face and mount animations

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drschlock
 
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Halloween talking skull with face and mount animations

Post by drschlock »

I started a project to build some sort of talking skull for Halloween where someone could speak into a microphone to make it say something. Ideally the eyes would move and the mouth would move in sync with the person speaking into the microphone.

I came across this electric demon costume with a waveshield voice-changer and face animations, which is a perfect place to start.

I set to work building a prototype using the waveshield and LED backpacks. Everything works great except that I cannot seem to run both the voice changer and the LED backpacks (eye & mouth animations) without very noticable noise being picked up over the microphone.

I am led to believe it comes from the I2C bus because if I disconnect the +5 volt power to the Led backpacks (effectively turning off the eyes & mouth), the voice changer works perfectly. I get no extra noise.

When I change the potentiometer that modifies the voice-changer pitch, the noise picked up also changes in pitch. I don’t quite understand how this noise can be picked up by the mic if only the LED Backpacks are running.

Any ideas on where this noise might be coming from? Do I need to add some sort of filters / capacitors to the circuit?

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adafruit_support_bill
 
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Re: Halloween talking skull with face and mount animations

Post by adafruit_support_bill »

It could be the i2c, or(more likely) switching noise from the multiplexed led display. Try to keep your audio wiring well separated from the display wiring. And some bypass caps between power and ground on the display may help.

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drschlock
 
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Re: Halloween talking skull with face and mount animations

Post by drschlock »

Hey Bill, thank you for the suggestions!

I tried adding capacitors (up to 1000uf) between +5 volts and ground for the I2C and between the Microphone's +3.3V and ground. It only seemed to reduce the noise by about 15%.

I also tried moving the +5 volts lead farther away but to no avail. Here is a picture of the board:
2015-10-05 21.21.03.jpg
2015-10-05 21.21.03.jpg (859.24 KiB) Viewed 415 times
. I don't see anything obvious with the wiring though.

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adafruit_support_bill
 
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Re: Halloween talking skull with face and mount animations

Post by adafruit_support_bill »

Another thing you can try is to use a separate power supply for the i2c matrix. Connect all the grounds back to the Arduino, but keep the 5v supply lines separate.

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drschlock
 
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Re: Halloween talking skull with face and mount animations

Post by drschlock »

That did it! Thank you Bill! I hooked up a separate 5V power supply to the LED backpack VCC rail and connected the ground to the other grounds for the Arduino UNO. The noise is reduced by about 90%. I can clearly speak through the voice changer now while having the face animations. Now on to tweaking the scary display. Thank you again for your help!

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Re: Halloween talking skull with face and mount animations

Post by adafruit_support_bill »

Great! Be sure to post pictures when you are done. :)

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