Bluetooth Stereo Amplifier Board 3.7‑5V BT 5.0 Lossless Sound Quality Car Speaker Amplifier for DIY with LED Indicator                       Feature:     1. Decoding format is WAV+APE+FLAC+MP3 lossless decoding, stereo output. With the basic functions of BT 5.0, 15m / 49ft transmission (barrier free), lossless sound quality, Bluetooth 5.0 is backward compatible with Bluetooth 4.2, 4.1, 4.0.      2.   This product has the function of charge and discharge, and can be powered by USB power. Note: If the USB is suddenly disconnected during charging and playback, the Bluetooth will auto restart, auto connect and maintain the previous playback state      3. When a single USB is powered, the red light flashes for normal power supply; When a single battery is powered, the yellow light is always on for normal power supply; Flashing light for charging, and always on red light for fully charged.      4. After connecting to Bluetooth, turn on the call mode in the Bluetooth settings. If there is a call coming in, you can answer/hang up through the PLAY/STOP button. (Note: this module does not have a microphone)       5. When using a computer sound card, tin the pads of the two boxes corresponding to the sound card on the back of the module, then connect it to the computer USB port through a USB cable, then it can be used as a sound card. The sound played by this computer is output through the interface of the module.             Specification:             Item Type: Bluetooth Stereo Amplifier Board  Material: PCB  Color: Red  Bluetooth Version: V5.0 (Chip: JL6925A)  Transmission Distance: About 15m / 49ft  Power Supply: USB Power Supply (universal Micro USB 5V power supply), 3.7-5V power supply pad (to realize external 3.7-5V lithium battery power supply modification)  3.5mm Stereo Interface: Standard 3.5mm interface, output stereo sound source, can be inserted into headphones, connected to power amplifiers and other equipment  Transmission Protocol: A2DP/AVCTP/AVDTP/HFP  SNR: 90dB  Total Harmonic Distortion +Noise: -70dB  Crosstalk: -86dB  DNR: 91dB  Pairing Instructions: Connect the power supply, the blue indicator light flashes, and enter the Bluetooth mode; when you hear the voice broadcast "The Bluetooth device is to pair", it means entering the Bluetooth mode and waiting for pairing; after the mobile phone Bluetooth searches for "JH-BT", Click Connect. When you hear the voice broadcast "The Bluetooth device is connected successfully",  It means that the decoder board is successfully connected to the mobile phone, the blue indicator light is long on, and the music can be played, and the blue indicator light is flashing at this time.                    Package List:     1 x Bluetooth Stereo Amplifier Board