I built a portable speaker out of wood with internal parts from Adafruit and Aliexpress. When powered on, with no music playing or at low volume there is an annoying electronic hum. When I disconnect the Digital BT player, and only amp is connected - the awful hum is gone. I have a conversation going with the Chinese via Aliexpress regarding the media player and they say it is because the Power Supply (+12V, 3s 18650 LIon with BMS charging) is too close to their "decoder" they call it. I'd like to find a way to get rid of the noise and have a clean signal (how do small BT speakers work when PS and source are closer- maybe shielding? Isolator? Any ideas or links? (I'd include a video of the problem but I don't see a suitable option for me through the media function).
Parts:
https://www.aliexpress.com/item/1005002835141520.html (Audio player BT, USB, aux etc)
https://www.adafruit.com/product/1752 (Max 9744 20W amp)
https://www.adafruit.com/product/1732 (20W speakers, nothing special)
Parts:
https://www.aliexpress.com/item/1005002835141520.html (Audio player BT, USB, aux etc)
https://www.adafruit.com/product/1752 (Max 9744 20W amp)
https://www.adafruit.com/product/1732 (20W speakers, nothing special)
Connect the output of the BT module to another amp and see if the noise is still there.
This boombox has an external power supply doesn't it, does it still do it running on the battery's?
This boombox has an external power supply doesn't it, does it still do it running on the battery's?
I run it mainly on the batteries though it does run off a 12V plug in wall charging unit. Both plug in and batteries are connected to a BMS module to balance charge the 18650 cells (plug in) or discharge cells (during play). Plugging in to a wall makes no difference to the hum sound.