DC4.8-6V 3 Modes Digital Servo Tester / SG90 Servo Motor Gear For RC Helicopter

Mini SG90 Servo. PPM signal: A PPM signal test function is available. On the display, the input PPM signal changes while the input PPM signal is synchronised to the servo power-up and automatically enters manual mode (20us 50h) to simulate the servo signal cycle with a frequency of 50 Hz.

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