Note that the product has been upgraded to a new model, adding a sliding switch to switch the working mode Product model: HF69BBluetooth power amplifier board, low standby heat, good stereo sound quality, suitable for small Bluetooth speakersOutput power 6W+6W dual channel stereoApplicable speaker impedance: 6 ohms, 8 ohms (the speaker impedance is too small, the volume will be turned on and the sound will be cut off)Power supply voltage: 5VDC or 3.7 volt lithium battery (the wiring is too long in use, the battery has no power, the voltage is too low, and the volume will be slightly turned on and the sound will be broken)Power supply current: more than 1A of full power (the power supply current is not enough and the volume will be broken when the volume is turned on)Charging interface: In the case of using lithium battery power supply, the charging interface 5 volt power supply or mobile phone charger can charge a single cell lithium battery (The charging management circuit limits the maximum voltage of the battery to 4.2VDC) Friendly reminder: when the slide switch is ON, the Micro USB port is a charging port, which can be operated by the lithium battery power supply; when the slide switch is OFF, the Micro USB port is the power supply port, you can work without connecting the lithium battery. When the product is in use, a large volume is turned on, and the speaker is disconnected. Please check the power supply. If the output current of the power supply is not enough, an intermittent sound will appear. Users who do not understand should not buy it. It is not recommended to use speakers with low impedance.