Low power Bluetooth amplifier DIV

1. Introduction to project functions

Design a low-power Bluetooth amplifier and make a small speaker.

This design draws on (1) part of the Bluetooth module design of Chai Gong’s TPA3116+M18 Bluetooth digital amplifier https://oshwhub.com/winton/d-lei-shuo-zi-gong-fang;

(2) Mogong’s PAM8407 simple application circuit in the fourth episode of PCB design explanation in the 2021 Lichuang summer training camp live broadcast.

Currently, both wired input and Bluetooth input are available.

It is recommended to use Bluetooth input. There is basically no noise in Bluetooth input, but there is some noise in wired input. It is initially judged that there is a problem with the pin connection of the headphone interface.

Can switch between wired and Bluetooth modes.

The shutdown circuit is set. You can use the toggle switch to turn the power on or off when connecting to the power supply. There is a small light-emitting diode as an indicator light.

You can use a touch switch on the board to control the volume increase or decrease.

In Bluetooth mode, you can use the buttons to switch between the previous and next songs, turn off or on Bluetooth, and pause or start song playback.

2. Project attributes

It is published for the first time and is original. The project refers to TPA3116+M18 Bluetooth digital amplifier https://oshwhub.com/winton/d-lei-shuo-zi-gong-fang.

Make major changes to the circuit according to your actual situation.

Because what we want to do is a low-power audio power amplifier, and based on cost considerations, we do not use TPA3116 and use PAM8407 instead.

* 3. Open source agreement

GPL3.0 open source agreement

*4. Hardware part

The main audio power amplifier chip is PAM8407. This chip is not commonly used, but it is relatively cheap. The amplification circuit basically uses the simple application circuit in the data sheet of the chip.

The Bluetooth module used was purchased directly online. The model is M18. The Bluetooth module circuit uses the M18 application circuit, but there are some changes. The 100mH inductor is not used to filter the power supply because there is already a capacitor filter.

The voltage input adopts 5V miniUSB input, which can be used directly with a computer, power bank, etc., which is more convenient.

The 100μF capacitor package in the power filter part should be replaced with a direct plug, but I forgot when drawing the schematic, so the PCB is a patch capacitor. I used a 10μF chip capacitor instead, using the 5V power supply voltage transmitted by miniUSB, and using a small A small l filter capacitor has little effect on filtering.

5. Software part

none

6. BOM list

Please enter content...

In addition to the BOM list, there is an 8Ω 3W small speaker and an M18 Bluetooth module.

Note: BOM list involved in the project. Please upload a screenshot of the BOM at this location. Please upload the list details in PDF format to the attachment. Suggestions include model, brand, name, packaging, procurement channels, usage, etc. The specific content and form should be based on clearly expressing the project composition.

*7. Contest LOGO verification

Please upload a project picture containing the competition logo. The logo will be printed on the PCB in the form of silk screen printing.

Click the zip to download the competition logo! (Contest logo).zip

* 8. Demonstrate your project and record it as a video for uploading

Video requirements: Please shoot horizontally, with a resolution of no less than 1280×720, in Mp4/Mov format, and the size of a single video is limited to 100M;

Video title: Lichuang Electric Competition: {Project Name}-{Video Module Name}; such as Lichuang Electric Competition: "Autonomous Driving" - Team Introduction.

More details: https://diy.szlcsc.com/posts/06c94d90c2c447dfbd9ed7339ff4a5b1