Description:  XH-A105 digital power amplifier board with high fidelity and two-channel stereo sound quality; input voltage is DC 12~24V, audio input supports Bluetooth, TF card, AUX 3.5mm audio line input, can be directly connected to mobile phone, MP3, etc.; power amplifier board It also comes with a volume adjustment function, which rotates the chirp potentiometer clockwise to zoom in and counterclockwise to decrease.     Specification:  Product Name: Two-channel Bluetooth 5.0 power amplifier board.  Input voltage: DC12-24V.  Current: more than 3A.  Output power: 100W*2.  Audio input: Bluetooth, TF card, AUX.  Number of channels: two channels.  Size: 92*85*20MM.  Installation aperture: 3MM.  Installation hole distance: 85*5*78.5MM.    Bluetooth operation instructions:  When the power amplifier board is connected to the power supply and the Bluetooth is not connected, the Bluetooth indicator will flash rapidly. When the Bluetooth connection is successful, the Bluetooth indicator will stop flashing. When the song is played, the Bluetooth indicator will flash slowly.     Note:  1. Connect the power input to the DC12-24V power supply. When the power is on, the power indicator will light red and the blue light will flash blue.  2. Connect the audio input to the audio source, such as MP3, mobile phone, computer, TF card, etc.  3. Connect the audio output to the speaker, paying attention to the positive and negative.     Bluetooth / TF card volume hole:  When the audio input uses Bluetooth or TF card, you can connect the power cord to the '+ VOL -' three holes to adjust the volume and switch songs.  1. '+' and 'VOL' connection:  increase the volume.  2. '-' and 'VOL' connection: reduce the volume.  About choose Audio Input : The Board will Automatic Selection the last audio input .If you use the Bluetooth Audio input ,and then connect the AUX ,so the board will Automatic choose the AUX Audio input       Package included:  1 x Amplifier Board