Description

Specification:
MH-M38:
Number Pin Description
1 5V power supply positive 5V
2 GND power supply negative pole
3 VBAT lithium battery positive electrode 3.7-4.2V
4 L+/L-left channel output (directly connected to the speaker)
5 R+/R - Right channel output (directly connected to the speaker)
1. Power supply: You can directly use the MICRO USB Android cable 5V for power supply, or connect an additional 5V power supply or 3.7V lithium battery (as shown in the following figure). Note that the power supply interfaces for 5V and 3.7V are different. 5V is connected to 5V and GND, while 3.7V lithium batteries are connected to VBAT and GND. High working current 5V2A, it is recommended to use a 5V2A regulated power supply for power supply.
2. Supports USB sound card, driver free (plug and play). Connect the module to the computer using a USB data cable, and the computer can play music to output through the module amplifier
3. Audio output: Output left and right stereo audio signals, which can be connected to two 2-8 ohm and 3-5W speakers respectively, and use 4 ohm and 5W speakers for push and save.
4. This product already comes with a dual 5W power amplifier circuit, and cannot be used with another power amplifier! The outputs of two power amplifiers cannot be connected in parallel or the negative electrodes connected together, as it may damage the power amplifier chip.

Function description:
Bluetooth-Compatible V4.2 version, supports Bluetooth-Compatible automatic rewind technology, supports WAV/WMA/FLAC/APE/MP3 lossless decoding, and stereo dual channel output.
After the module is powered on, the phone searches for the Bluetooth-Compatible name MH-M18/MH-M28/MH-M38. After connecting to Bluetooth-Compatible, music can be played;
Module blue indicator light:
When Bluetooth-Compatible is not connected, the indicator light flashes quickly;
When Bluetooth-Compatible is connected, the indicator light remains on;
When Bluetooth-Compatible is playing, the indicator light flashes slowly.

Precautions:
Signal interference: Bluetooth-Compatible antennas are susceptible to high-frequency or strong electromagnetic signal interference and should be placed away from transmitting devices such as wireless devices. And the board should not be close to metal objects, maintain a certain distance.
If there is current noise on the power amplifier board, which is caused by ground wire interference, it is recommended that the output end of the Bluetooth-Compatible module not be plugged in, but soldered, especially if the ground wire needs to be soldered, and the wire should not be too long, the shorter the better, and try to be thicker. The issue with audio grounding on the power amplifier board should be connected to the ground of the audio input end of the power amplifier. This grounding point can be welded at different positions to achieve low current sound. It is recommended to separate the power supply for Bluetooth-Compatible and amplifier board, and isolate the Bluetooth-Compatible ground and amplifier ground.
Due to the bare board design of this product, it is recommended not to touch the components on the board with your hands, as it may cause static electricity to kill the chip and cause it to burn.
Warning: The charging interface of this product is in limited current charging mode and does not come with charging management! For the safety of your life and property, please be sure to use lithium batteries with protective plates produced by reputable manufacturers. If any losses are caused due to improper use, our company will not bear any responsibility!
Additionally, the following two points should be noted when using MH-M18:
Power supply: By default, 5V is used for power supply. If you need to use a 3.7V lithium battery for power supply, you need to replace the diode (as shown in the figure) with a 0 ohm resistor of 0603, or simply short circuit both ends of the solder pad.
The Bluetooth-Compatible audio module has very high requirements for power supply, which can affect the quality of the audio. It is recommended to add an LC filtering circuit, especially for switching power supply (such as mobile phone chargers).
MUTE mute port: This module outputs a high level 3.3V during mute and a low level 0V during playback. If the mute high level of the power amplifier board is effective, it can be directly connected. If the mute of the power amplifier board is controlled at a low level, a reverse circuit needs to be added.

Note:
Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you!
Please allow 1-2cm measuring deviation due to manual measurement.

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