FEETECH Sub-Micro Servo FS0403-FB with Position Feedback

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Pololu item #: 3438
Brand: FEETECH
RoHS 3 compliant


This version of the FS0403 sub-micro servo from FEETECH is specially modified to provide access to the feedback potentiometer through a fourth (green) wire, allowing you to directly measure the position of the output. This extra information enables more complex robotics applications, such as determining when the servo has reached its target, detecting when the output is blocked, or implementing your own higher-level closed-loop position control.

Key specs at 6 V: 0.08 sec/60°, 10 oz-in (0.7 kg-cm), 6 g.

Pictures

FEETECH Sub-Micro Servo FS0403-FB with Position Feedback.

FEETECH FS0403 Sub-Micro Servo with a LEGO Minifigure as a size reference.

An example of hardware included with the FEETECH FS0403 sub-micro servo. Actual hardware might vary.

Servo and feedback connectors on the FEETECH servos with position feedback.




Overview

The FS0403-FB is a specially modified version of FEETECH’s FS0403 sub-micro analog servo that provides access to the feedback potentiometer through a fourth (green) wire, which makes it possible to directly measure the output angle. With this extra information, you can determine when the servo has reached its target position (or detect if something is interfering with its ability to get there). This feedback also enables more complex closed-loop control of the servo from your main controller.

Like the FS0403, the FS0403-FB works with standard RC servo pulses, providing an operating angle of approximately 120° over a servo pulse range of 900 µs to 2100 µs. The feedback voltage varies linearly over this range by a couple of volts. As with most servos, the pulse range can be expanded to achieve an expanded operating angle, but the limits of this are not specified by FEETECH. (In our tests, we were able to get an expanded range of approximately 180° over a pulse range of 650 µs to 2500 µs, but as this is not part of FEETECH’s official specifications, it is possible different units will behave differently in this regard.)

The servo signal, power, and ground are provided through a 3-wire servo cable that is terminated with a standard JR-style connector, which is Futaba-compatible. The feedback is accessible through a separate green wire that is terminated like our female premium jumper wires and works with standard 0.1″ male header pins. These cables are approximately 6″ (15 cm) long.

Servo and feedback connectors on the FEETECH servos with position feedback.

For more information about this servo, see the FS0403 datasheet (97k pdf) (please note that this is the datasheet for the standard FS0403 sub-micro servo, so it does not include any information about the special feedback modification).

An example of hardware included with the FEETECH FS0403 sub-micro servo. Actual hardware might vary.

Note that, as with most hobby servos, stalling or back-driving this servo can damage it.

Dimensions

Size: 20.0 × 8.3 × 19.3 mm
Weight: 6 g

General specifications

Digital?: N
Speed @ 6V: 0.08 sec/60°
Stall torque @ 6V: 0.7 kg·cm
Speed @ 4.8V: 0.09 sec/60°
Stall torque @ 4.8V: 0.6 kg·cm
Hardware included?: Y
Lead length: 6 in

File downloads

Frequently-asked questions

What are the wires coming out of my servo?

Most standard radio control (RC) servos have three wires, each a different color. Usually, they are either black, red, and white, or they are brown, red, and orange/yellow:

  • brown or black = ground (GND, battery negative terminal)
  • red = servo power (Vservo, battery positive terminal)
  • orange, yellow, white, or blue = servo control signal line

Please check the specs for your servo to determine the proper power supply voltage, and please take care to plug the servo into your device in the proper orientation (plugging it in backwards could break the servo or your device).

Note: Some of the servos we carry also have an optional fourth green wire that is separate from the three standard ones. This wire provides access to the feedback potentiometer, allowing you to directly measure the position of the output. The servos with this extra wire have "with Position Feedback" at the ends of their product names. The picture below is an example of such a servo.

FEETECH Sub-Micro Servo FS0403-FB with Position Feedback.

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