Adafruit Micro Lipo + Bluetooth + Amplifier

[eddie121]

Hey folks,

I've read that using a small DIY Bluetooth receiver board + digital amplifier board, all connected to the same power source (LiPo battery) will incur a ground loop.
Could you let me know your thoughts on that, if I were to use your Adafruit Micro Lipo product linked below?

Adafruit Micro Lipo w/MicroUSB Jack - USB LiIon/LiPoly charger
http://www.adafruit.com/products/1904

Stereo 2.8W Class D Audio Amplifier - TS2012 PRODUCT ID: 1552:
https://www.adafruit.com/products/1552

Bluetooth A2DP board (couldn't find anything on your site):
http://www.ebay.com/itm/2pcs-XS3868-Blu ... 4897.l4275

I plan to use a tiny 150+mAh LiPo battery as the single power source.

Thanks!

[eddie121]

I do already have this Bluetooth USB module though. I supposed I could remove it from the plastic casing and solder it to the battery that the amp is also connecting to?

https://www.adafruit.com/products/1327

[adafruit_support_mike]

Ground loops only happen through signal lines that allow DC voltage to pass through. If you send the audio signals into the amplifier through isolation capacitors, that can't happen.

[eddie121]

Ground loops only happen through signal lines that allow DC voltage to pass through. If you send the audio signals into the amplifier through isolation capacitors, that can't happen.

Interesting, thanks for the swift response!!
I had to Google this up since I've never used one before.
Do you think something like this would work?

1uF 10V DC Film Capacitor:
http://www.digikey.com/product-detail/e ... ND/4431988

[adafruit_support_mike]

Should do.. film capacitors have pretty good specs.

That's a 1206 SMT package, just so you know. Not all that hard to solder, but you do need some kind of PCB to hold it. Since the breakout has connection holes, you might want to look for a through-hole version.

[eddie121]

Should do.. film capacitors have pretty good specs.

That's a 1206 SMT package, just so you know. Not all that hard to solder, but you do need some kind of PCB to hold it. Since the breakout has connection holes, you might want to look for a through-hole version.

Thanks, Mike!
At least I can Google in the right direction now. :)
Have an awesome weekend!

[theboydidgood]

Hi Eddie,

Did you ever solve this issue?

I ask as I'm using the Adafruit 10+10w amplifier with a USB Bluetooth receiver which shares the same power supply (via a step-down converter) and I get all sorts of buzzes and whining. I've tried using two separate power supplies but the moment I connect the output from the bluetooth to the input on the amp I get the buzzing.

I think this isolation capacitor might be the answer but I'm pretty new to all this and don't entirely understand the problem or how th implement the solution. Any pictures of your setup or other advice would be a great help.

Many thanks
Marcus.