HS-785HB Servo


The HS-785HB servo is unique due to its ability to rotate multiple turns while retaining positioning feedback.  While most servos are limited to approximately 180 degrees absolute max, the HS-785HB can rotate just over 8 turns given the proper PWM signal range.  With most hobby radio systems the HS-785HB servo range is likely to be just shy of 4 rotations (assuming a 1050-1950usec PWM signal) however when using the servo with a servo controller capable of sending a wider PWM range (Arduino, Raspberry Pi, Pololu Servo Controller, etc.), the servo is able to be driven further without any modifications necessary.  This large scale servo has wear resistant Karbonite gears and an output shaft supported by two ball bearings to ensure years of reliable service. 

How Far Will This Servo Rotate?

The answer to this question is partially dependent on what you are using to control the servo.
Click for a quick video explanation.

With an Average Radio System:
3.92 Turns
Your average transmitter and receiver will output a relatively narrow PWM signal range.

Radio System + Travel Tuner:
7.85 Turns
Adding a Servo Travel Tuner to your radio system setup will allow you to achieve wide PWM signal ranges.

Wide Signal Controllers:
7.85 Turns
Controllers such as the Servo Commander, Arduinos, and Raspberry Pi servo hats can usually send a wide signal.

Tech Tips


Output Shaft Style C24T Spline
Voltage Range 4.8V - 6.0V
No-Load Speed (4.8V) 1.68sec/360°
No-Load Speed (6.0V) 1.4sec/360°
Stall Torque (4.8V) 152.75 oz-in (11 kg.cm)
Stall Torque (6.0V) 183 oz-in (13.2 kg.cm)
Max PWM Signal Range 600-2400μsec
Travel per µs 1.570°
Max Rotation 2826°
Pulse Amplitude 3-5V
Operating Temperature -20°C to +60°C
Current Drain - idle (4.8V) 8mA
Current Drain - idle (6.0V) 8.7mA
Current Drain - no-load (4.8V) 230mA
Current Drain - no-load (6V) 285mA
Continuous Rotation Modifiable Yes
Direction w/ Increasing PWM Signal Clockwise
Deadband Width 8µs
Motor Type 3 Pole Ferrite
Feedback Style 5KΩ Potentiometer
Output Shaft Support Dual Ball Bearings
Gear Material Karbonite
Wire Length 11.81" (300mm)
Weight 3.88oz (110g)
Wire Gauge 22AWG
Servo Size Large

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