DIY Mini Bluetooth Speaker for Clear Audio

If your desktop power supply is too complicated and the 12V integrated power supply is overloaded with a dozen devices, the audio signal extracted from HDMI and connected to external active speakers results in annoying noise that barely allows you to hear faint useful sounds. If that's the case, why not DIY a mini Bluetooth speaker?

This M01 mini Bluetooth amplifier from the Desktop Sound series adopts a built-in isolated power supply to avoid external power interference.

Input voltage: 12-24V-DCIN/TYPEC built-in 12V decoy. 12V input can basically run at full power, and the higher the voltage, the greater the power margin. Output power: PAM8407DR - 2x2.4W D class.

Audio source connection: default Bluetooth audio source connection when starting up, and switch to 3.5mm-LIN input by pressing a button.

Appearance size: PCB=43*45mm, whole machine= length 47.4 (including baffle) * width 45 * height 18.5mm.

Built-in Bluetooth (a few yuan for integration and free shipping on a certain platform) is said to be 5.0. This project uses the JL AC22BP, which seems to have removed USB. The previous AC20BP had USB, but the circuit is different. That's it, with this speaker you can listen to music and even dance to it with 5W output power. For general desktop use, it only consumes about 0.3W and is very power-saving. If the volume is too high, it may become too noisy.

Version 2.0 released on March 6, 2023 added a circuit to eliminate switching and shutdown noise, added a Bluetooth always-on jumper, and is compatible with two types of decoy chips.

EPC-13S - 1:1 isolation transformer.