MH-M18 / M28 / M38 is a power-low Bluetooth design solution that supports the latest Bluetooth 4.2 transmission, two-channel stereo lossless playback, and Bluetooth wireless transmission when the module is connected to Bluetooth, which is very convenient  .  In an open environment, the Bluetooth connection distance can be up to 20 meters.
Widely used in a variety of Bluetooth audio reception, a variety of audio DIY modification.

For your different needs, we offer 3 versions for you to choose from:

Function Description:

Bluetooth V4.2 version, supports Bluetooth automatic connection technology, supports WAV/WMA/FLAC/APE/MP3 lossless decoding, stereo dual channel output.
After the module is powered on, the mobile phone searches for the Bluetooth name MH- M18/MH-M28/MH-M38, and can play music after connecting Bluetooth.

Module blue indicator light:
When the Bluetooth is not connected, the indicator light flashes quickly;
When the Bluetooth connection is on, the indicator light is always on;
When the Bluetooth is playing, the indicator light flashes slowly.

MH-M18:
MUTE mute control terminal: used to control the power amplifier board. When muting, MUTE outputs a high level of 3.3V, and outputs a low level during playback.

KEY button control: This function requires additional connection of resistors and buttons .

Volume power off function: The default output is 100% volume.  Press the button to control the volume increase and decrease. If the control volume is less than 15%, the volume output will be 15% after re-powering; if the control volume is greater than 15%, the original volume will remain unchanged after power-on.

MH-M28:

1. Power supply: You can directly use the MICRO USB Android cable 5V for direct power supply, or you can also connect 5V power supply or 3.7V lithium battery. 

 Note that the 5V and 3.7V power supply interfaces are different. The 5V voltage is connected to 5V and GND, and the 3.7V lithium battery is connected to VBAT and GND.

2. Audio output: The earphone can be directly connected to the 3.5mm audio interface, or it can be wired for the audio input of the power amplifier board (interface L/R/AGND can be directly wired)

MH-M38:
1. Power supply: You can directly use the MICRO USB Android cable 5V for direct power supply, or you can also connect 5V power supply or 3.7V lithium battery. 
Note that the 5V and 3.7V power supply interfaces are different . The 5V voltage is connected to 5V and GND, and the 3.7V lithium battery is connected to VBAT and GND.

2. Audio output: The earphone can be directly connected to the 3.5mm audio interface, or it can be wired for the audio input of the power amplifier board (interface L/R/AGND can be directly wired).

1. Power supply: You can directly use the MICRO USB Android cable 5V for direct power supply, or you can also connect 5V power supply or 3.7V lithium battery.  Note that the 5V and 3.7V power supply interfaces are different. 5V is connected to 5V and GND, and the 3.7V lithium battery is connected to VBAT and GND.

The maximum operating current is 5V2A. It is recommended to use a regulated power supply of 5V2A for better sound quality.

2. Support USB sound card, free drive (plug and play).  Connect the module to the computer with the USB cable, and the computer can play music through the module amplifier output.

3. Audio output: output left and right channel stereo audio signals, can be connected to two 2- 8 euro, 3-5W speakers, push 4 O 5W speakers.

4. This product has its own dual 5W power amplifier circuit, and must not be connected to another amplifier!  The outputs of the two amplifiers cannot be connected in parallel or the negative poles are connected together, otherwise the power amplifier chip is damaged.