M38 HIFI Stereo Wireless Bluetooth Receiver with 5W Output

Features:
M28 and M38 support micro power supply,M28 provides audio earphone interface,and M38 contains internal power amplifier.All of them are powered by lithium battery.
Only M18 includes volume adjustment and memory,MUTE silent interface and button extender.
Bluetooth version V4.2,newly bluetooth version and provides you perfect using experience.,support automatic bluetooth connection technique,support WAV/WMA/FLAC/APE/MP3 lossless decode,3D double dual track output.
When module powers on,searching bluetooth name MH-M18/MH-M28/MH-M38 on your phone,and connect with bluetooth,then playing music.
Blue indicator module: 1.Not connected: flash;2.Connecting: Steady light;3.Playing: slow flash.

M38:
1. Power supply: it can be directly used for power supply with MICRO USB android cable 5V, or connected with 5V power supply or 3.7v lithium battery. Note that the power supply interface of 5V and 3.7v is different. 5V is connected to 5V and GND, and 3.7v lithium battery is connected to VBAT and GND. The maximum operating current is 5V2A. It is recommended to use a 5V2A regulated power supply for better sound quality.
2. Support USB sound card, free of drive (plug and play). Connect the module with the computer with USB data cable, and the computer can output power through the module by playing music.
3. Audio output: the stereo audio signals of left and right sound channels can be output, which can be connected to two speakers of 2-8 euros and 3-5w respectively, and the speakers of 4-5w can be used for pushing storage.
4. This product has its own dual 5W power amplifier circuit, it must not be used with another power amplifier! The outputs of the two power amplifiers cannot be connected in parallel or the negative terminals can be connected together, otherwise the power amplifier chip will be damaged.
module only,other accessories demo in the picture are not included!

Caution:
Signal interference: bluetooth antenna is extremely vulnerable to high frequency or strong electromagnetic signal interference, as far as possible away from the location of sending wireless equipment. 
And the board can not be close to the metal objects, maintain a certain distance.
If there is a current sound in the power amplifier board, it is caused by the interference of ground wire. 
It is suggested that the output end of bluetooth module should not use plug-in wire, and welding wire is necessary, especially the ground wire. Moreover, the wire should not be too long, the shorter the better, and it should be thicker as far as possible. 
The problem of audio ground at the junction of the power amplifier board must be connected at the ground of the power amplifier audio input. This junction can be tried to be welded at different positions to achieve the lowest current sound. 
It is suggested that the power supply of bluetooth and power amplifier board should be separated.
As this product is designed for the bare board, try not to touch the components on the board with your hands, which may easily lead to static electricity killing the chip and burning it.