<div class="detailmodule_html"><div class="detail-desc-decorate-richtext"><div><span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><strong>Product Introduction:</strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> This product MH-M18/M28/M38 is a low-power Bluetooth design solution that supports new Bluetooth 4.2 transmission and lossless stereo playback. After the module is connected to Bluetooth, it can quickly achieve Bluetooth wireless transmission, which is very convenient. In an open environment, the Bluetooth connection distance can reach up to 20 meters.<br /> Widely used in various Bluetooth audio receivers, DIY modification of various audio systems, etc.</span></span><br /> <br /> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><strong>Function Description:</strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> Bluetooth V4.2 version, supports Bluetooth automatic reconnection technology, supports WAV/WMA/FLAC/APE/MP3 lossless decoding, and stereo dual channel output.<br /> After the module is powered on, the phone searches for the Bluetooth name MH-M18/MH-M28/MH-M38, and once connected to Bluetooth, music can be played;<br /> Module blue indicator light:<br /> When Bluetooth is not connected, the indicator light flashes rapidly;<br /> When Bluetooth is connected, the indicator light stays on;<br /> When Bluetooth is playing, the indicator light flashes slowly.</span></span><br /> <br /> <span style="font-size:20px"><span style="font-family:Arial, Helvetica, sans-serif"><strong><span style="background-color:rgb(241, 196, 15)">MH-M18 description:</span></strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> KEY: Key control terminal (4 key functions, additional resistors required)<br /> MUTE: Mute control terminal (outputs high level 3.3V during mute and low level during playback)<br /> VCC: Positive power supply 5V (lithium battery 3.7V power supply requires short-circuit diode)<br /> GND: Negative pole of power supply<br /> L: Left channel output<br /> R: Right channel output<br /> <br /> MUTE mute control terminal: used to control the power amplifier board, MUTE outputs a high level 3.3V during mute and a low level during playback.<br /> KEY button control: This function requires additional connection of resistors and buttons to achieve.<br /> Volume power-off hold function: default output volume. Control the volume increase and decrease through buttons. If the volume is controlled to be less than 15%, the volume output will be 15% after powering on again; If the volume is controlled to be greater than 15%, the original volume will remain unchanged after powering on again.</span></span></div> <p style="margin:0px;margin-bottom:0px;margin-top:0px;margin-left:0px;margin-right:0px;display:block;width:100%"></p> <div><br /> <br /> <span style="font-size:22px"><span style="font-family:Arial, Helvetica, sans-serif"><strong><span style="background-color:rgb(241, 196, 15)">MH-M28 description:</span></strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> 5V: Positive pole of power supply 5V<br /> GND: Negative pole of power supply<br /> VBAT: Lithium battery positive electrode 3.7-4.2V<br /> L: Left channel output<br /> R: Right channel output<br /> AGND: Audio Ground<br /> <br /> 1. Power supply: It can be directly powered by a MICRO USB Android cable with 5V, or it can be connected to a 5V power supply or a 3.7V lithium battery separately. Note that the power supply interfaces for 5V and 3.7V are different. The 5V voltage is connected to 5V and GND, while the 3.7V lithium battery is connected to VBAT and GND.<br /> 2. Audio output: The headphones can be directly connected to the 3.5mm audio interface, or wired for audio input on the amplifier board (interface L/R/AGND can be directly wired).</span></span></div> <p style="margin:0px;margin-bottom:0px;margin-top:0px;margin-left:0px;margin-right:0px;display:block;width:100%"></p> <div><br /> <br /> <span style="font-size:22px"><span style="font-family:Arial, Helvetica, sans-serif"><strong><span style="background-color:rgb(241, 196, 15)">MH-M38 description:</span></strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> 5V: Positive pole of power supply 5V<br /> GND: Negative pole of power supply<br /> VBAT: Lithium battery positive electrode 3.7-4.2V<br /> L+/L -: Left channel output (directly connected to speaker)<br /> R+/R -: Right channel output (directly connected to speaker)<br /> 1. Power supply: It can be directly powered by a MICRO USB Android cable with 5V, or it can be connected to a 5V power supply or a 3.7V lithium battery separately. 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.<br /> The working current is 5V2A. It is recommended to use a 5V2A regulated power supply for better sound quality.<br /> 2. Supports USB sound card, driver free (plug and play). Connect the module to the computer using a USB cable, and the computer can play music through the amplifier output of this module<br /> 3. Audio output: Output stereo audio signals for left and right channels, which can be connected to two 2-8 ohm and 3-5W speakers respectively. Use 4-ohm and 5W speakers for push storage.<br /> 4. This product comes with a dual 5W amplifier circuit, and must not be connected to another amplifier for use! The outputs of two amplifiers cannot be connected in parallel or the negative terminals cannot be connected together, otherwise the amplifier chip will be damaged.</span></span></div> <p style="margin:0px;margin-bottom:0px;margin-top:0px;margin-left:0px;margin-right:0px;display:block;width:100%"></p> <div><span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"></span></span><br /> <br /> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><strong>Matters needing attention:</strong></span></span> <span style="font-size:18px"><span style="font-family:Arial, Helvetica, sans-serif"><br /> Signal interference: Bluetooth antennas are extremely susceptible to high-frequency or strong electromagnetic signal interference, so they should be placed as far away as possible from transmitting wireless devices. And the board should not be in close proximity to metal objects, maintaining a certain distance.<br /> If there is a current sound when connecting to the power amplifier board, it is caused by ground wire interference. It is recommended that the output end of the Bluetooth module should not be plugged in, and must be soldered, especially for the ground wire. The wire should not be too long, the shorter the better, and it should be thicker as much as possible. The issue of the audio ground being connected to the grounding point of the amplifier board requires it to be connected to the ground at the audio input end of the amplifier. This grounding point can be welded at different positions to achieve the desired current and sound. Suggest separate power supply for Bluetooth and amplifier board, isolating Bluetooth ground and amplifier ground.<br /> Due to the bare board design of this product, try not to touch the components on the board with your hands as it may cause static electricity to kill the chip and burn it out.<br /> Warning: The charging interface of this product is limited to 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 legitimate manufacturers. If any losses are caused due to improper use, our company will not be held responsible!<br /> Additionally, when using MH-M18, the following two points should be noted:<br /> Power supply: default 5V power supply. If you need to use a 3.7V lithium battery for power supply, you need to replace the diode with a 0-ohm resistor of 0603, or simply short-circuit the two ends of the solder pad.<br /> The Bluetooth audio module has very high requirements for power supply, which can affect the quality of audio. It is recommended to add LC filtering circuit, especially switch power supply (such as mobile phone charger, etc.).<br /> MUTE Mute Port: This module outputs a high level of 3.3V when muted and a low level of 0V when played. If the mute high level of the 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</span></span></div> <p style="margin:0px;margin-bottom:0px;margin-top:0px;margin-left:0px;margin-right:0px;display:block;width:100%"></p> <p>&nbsp;</p> </div></div>