Pololu 3438 FEETECH Sub-Micro Servo FS0403-FB with Position Feedback
Pololu 3438 FEETECH Sub-Micro Servo FS0403-FB with Position Feedback
Pololu 3438 FEETECH Sub-Micro Servo FS0403-FB with Position Feedback
The Pololu 3438 FEETECH Sub-Micro Servo FS0403-FB is a compact, lightweight servo motor featuring integrated position feedback capability, delivering precise angular control in applications where space and weight are critical constraints. Professional roboticists, drone manufacturers, and precision automation engineers rely on this servo for its exceptional torque-to-weight ratio and analog feedback output that enables closed-loop position verification. This servo solves the fundamental problem of confirming actual servo position in real-time without relying solely on command signals, ensuring accuracy in demanding applications like robotic limbs, camera gimbals, and autonomous systems.
Product Overview
The FEETECH FS0403-FB sub-micro servo combines a high-speed brushed DC motor with a precision gearbox and integrated potentiometric feedback circuit, all housed in a ultra-compact aluminum chassis weighing just 9 grams. The servo operates on standard PWM control signals compatible with microcontrollers and servo controllers, while the analog feedback pin outputs a voltage proportional to the servo shaft position, enabling engineers to implement sophisticated position verification algorithms and closed-loop control systems. The 4.3mm servo arm and multiple mounting holes provide versatile integration options for miniaturized robotic platforms and precision instrumentation.
What distinguishes the FS0403-FB from standard servos is its integrated feedback circuit that continuously monitors the potentiometer wiper position, delivering real-time position data without additional sensors. This architecture eliminates the need for external position encoders or limit switches in many applications, reducing system complexity and cost. The servo's 4.8-6V operating range ensures compatibility with standard battery packs and regulated power supplies used in portable robotics and embedded systems, while the fast response time of approximately 0.12 seconds per 60 degrees makes it suitable for dynamic applications requiring rapid positional adjustments.
Key Specifications
| Specification | Details |
| Product Type | Sub-Micro Servo Motor with Position Feedback |
| Brand | FEETECH by Pololu |
| Origin | Original/Authentic |
| Warranty | 7 days on manufacturing defects |
| Shipping | 1-5 days from Bengaluru |
| Delivery | 7-8 days across India |
| Support | 24/7 via Email and WhatsApp |
| Operating Voltage | 4.8V to 6V DC |
| Stall Torque | 1.3 kg-cm at 4.8V, 1.6 kg-cm at 6V |
| Speed | 0.12 seconds per 60 degrees at 4.8V |
| Weight | 9 grams |
| Feedback Output | Analog voltage proportional to position |
| Control Signal | Standard PWM servo control 1-2ms pulse width |
| Dimensions | 23 x 12 x 29mm |
| Servo Arm | 4.3mm standard connector |
Key Features
- Integrated Position Feedback Circuit delivering analog voltage output proportional to shaft position for real-time closed-loop control without external encoders
- Lightweight Design at 9 grams with compact 23x12x29mm footprint enabling integration into space-constrained robotic platforms and aerial systems
- High Speed Response of 0.12 seconds per 60 degrees providing rapid positional adjustments for dynamic applications requiring quick servo repositioning
- Dual Voltage Compatibility operating from 4.8V to 6V DC allowing flexible power supply options and battery configurations in portable applications
- Standard PWM Control Interface compatible with Arduino, Raspberry Pi, and commercial servo controllers requiring no specialized driver electronics
- Aluminum Chassis Construction providing structural rigidity and thermal dissipation while maintaining minimal weight for weight-critical applications
Applications and Use Cases
- Robotic Arm Joints where position feedback enables precise limb positioning and collision detection in collaborative robotic systems and mechanical hands
- Autonomous Quadcopter Camera Gimbals requiring stabilized camera orientation with feedback verification to maintain framing accuracy during flight maneuvers
- Precision Instrumentation Control such as automated microscope stages, laboratory equipment positioning, and optical alignment systems demanding repeatable positioning
- Miniaturized Humanoid Robots where multiple sub-micro servos with feedback create articulated joints with verified position confirmation for coordinated movement
- RC Model Aircraft Control Surfaces using feedback to verify aileron, elevator, and rudder positions ensuring flight control system integrity
- Medical Device Actuation in portable diagnostic equipment and robotic surgical assistants requiring compact, feedback-enabled motion control
How to Use
The Pololu 3438 FEETECH FS0403-FB connects to your microcontroller using three primary connections: power supply positive and negative rails, and a PWM control signal input typically on a GPIO pin. Standard servo control applies PWM pulses between 1-2 milliseconds at 50Hz frequency, where 1.5ms centers the servo and shorter/longer pulses rotate counterclockwise/clockwise respectively. The analog feedback pin outputs a voltage between 0-5V proportional to the servo position, which you read using your microcontroller's analog-to-digital converter to verify actual position and implement feedback control loops.
To implement position feedback control, configure your microcontroller's ADC to continuously sample the feedback pin while sending PWM commands to the control input. Create a control loop that compares the desired position setpoint against the feedback voltage reading, adjusting the PWM pulse width until the feedback voltage matches your target. This closed-loop approach compensates for load variations, voltage fluctuations, and mechanical friction, ensuring the servo maintains commanded positions even under changing load conditions. Always include current-limiting resistors on the feedback line and decouple the power supply with a 0.1uF ceramic capacitor near the servo power pins to prevent control instability from power supply noise.
Frequently Asked Questions
What is the difference between this servo and standard servos without feedback?
Standard servos rely on command signal timing to estimate position, but cannot verify actual shaft location. The FS0403-FB includes an integrated potentiometer connected to the output shaft that continuously outputs an analog voltage representing true position. This enables closed-loop control where your microcontroller reads the feedback voltage and adjusts the control signal until the servo reaches the commanded position, providing position verification, load compensation, and improved accuracy in demanding applications.
Can I use this servo with Arduino and other microcontroller boards?
Yes, the FS0403-FB is fully compatible with Arduino, Raspberry Pi, and other microcontroller platforms. Connect the power and ground pins to your power supply, the PWM control pin to any GPIO pin configured for PWM output, and the feedback pin to an analog input pin. Use the Servo library for PWM generation and the analogRead function to sample the feedback voltage. The servo operates on 4.8-6V, so use a regulated power supply or battery pack within this range and ensure your microcontroller shares the same ground reference.
How do I convert the feedback voltage to actual servo position in degrees?
The feedback voltage is typically linear across the servo's operating range. First, calibrate by moving the servo to its minimum position and recording the ADC reading, then move to maximum position and record that reading. Calculate the voltage-to-degrees conversion using linear interpolation: degrees = min_degrees + (ADC_reading - min_ADC) * (max_degrees - min_degrees) / (max_ADC - min_ADC). For the FS0403-FB with approximately 180 degrees of travel, typical feedback ranges from 0.5V at minimum to 4.5V at maximum, though you should calibrate for your specific unit.
What is the maximum continuous load this servo can handle?
The FS0403-FB provides 1.3 kg-cm stall torque at 4.8V and 1.6 kg-cm at 6V. For continuous operation, use approximately 50-60 percent of stall torque to avoid motor burnout and excessive current draw. This translates to roughly 0.8 kg-cm continuous torque, suitable for light-duty applications. Exceeding continuous torque limits causes motor overheating, reduced servo lifespan, and potential control instability. Always calculate your load torque accounting for lever arm length and verify it stays within safe continuous limits.
When will I receive my order?
Orders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.
What is your return and warranty policy?
We offer a 7-day return policy on manufacturing defects only. Contact support within 7 days of receipt for free replacement or full refund. Not applicable for user damage or misuse.
Are bulk discounts available?
Yes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.
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- Returns: 7-day return policy on manufacturing defects only
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