Feetech ST-3009 7.4V 11.5kg Dual-Shaft TTL Serial Bus Servo

The Feetech ST-3009 is a compact smart servo with a brushless motor, metal gearbox and dual output shafts, built for robot joints, grippers and small actuation mechanisms where a standard PWM servo gives no feedback. It runs on the half-duplex TTL serial bus, so several servos daisy-chain on one line and each reports its own state back to the controller.

Key features

• Brushless motor with metal gears and ball bearings for long life under repeated motion
• 12-bit magnetic encoder: 4096 positions over 360°, with no mechanical angle limit
• Position control anywhere in 0-360°, plus continuous multi-turn rotation
• Feedback of position, speed, load, input voltage, current and temperature, with overload and over-current protection
• Aluminium alloy case and only 45g, light enough for multi-joint arms

Specifications

• Model: ST-3009-C001
• Operating voltage: 4.8-8.4V (7.4V nominal)
• Peak stall torque: 11.5kg.cm at 7.4V
• Rated torque: 3.8kg.cm at 7.4V
• No-load speed: 0.1 s/60° (100 RPM) at 7.4V
• Current: 390mA no-load and 2.8A stall at 7.4V; 6mA idle at 6V
• Interface: half-duplex asynchronous serial (TTL), digital packet
• Horn spline: 25T, 5.9mm OD
• Lead length: 200mm
• Dimensions: 20 x 30 x 36.5mm
• Weight: 45g (±1g)
• Operating temperature: -15 to 70°C

The 4.8-8.4V window takes a 2S LiPo or a regulated 7.4V supply directly; size the supply for 2.8A per servo at stall. Driving it from a PC or microcontroller needs a half-duplex TTL bus adapter, or a UART wired for half-duplex operation.