LewanSoul RC Digital Servo Tester 1 Channels Motor Servo Controller Centering Tool with Over-Current Protection & 2 Control Modes for RC Car Airplane Robots Tester Tool

You can use the knob to adjust the position manually or use the servo to return to the middle position Show the voltage of power supply Dimension: 50mm*35mm(1.96in*1.38in) Weight: 13.8g(0.03lb) How to use: 1)Connect the power to the tester 2)Plug the servo to the servo interface.+ is positive pole , - is negative pole, S is signal port, 3)The servo will rotate synchronously when you turn the knob 4)You can use the button below the knob to switch the mode to return to the middle position or knob control How to wire: 1)Connect the charging port of the 7.4v lithium battery to the white terminal directly 2)Or connect the power supply to the blue terminal, positive voltage 5~8.4v available.Package Content: 1 x Servo Tester'