FEETECH Standart Servo FS5103-FB with Position Feedback

This version of the FS5103B standard 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: 0.16 sec/60°, 53 oz-in (3.8 kg-cm), 43 g.

The FS5103B-FB is a specially modified version of FEETECH’s FS5103B standard-size 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 FS5103B, the FS5103B-FB works with standard RC servo pulses, providing a running angle of approximately 180° over a servo pulse range of 600 µs to 2400 µs. The feedback voltage varies linearly over this range by a couple of volts.

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 12″ (30 cm) long.

For more information about this servo, see the FS5013B datasheet (133k pdf) (please note that this is the datasheet for the standard FS5103B, so it does not include any information about the special feedback modification).

An aluminum servo horn that works with this servo is available separately:

Power HD SR8 Aluminum 25T Servo Horn.

Compatibility warning: In November 2018 FEETECH changed the case of this servo, making it no longer compatible with our Mounting Bracket for Standard-Size Servos. They will be switching back to the original case style, which will resolve this problem for future batches, but at this time this servo might not work properly with our mounting bracket.

The modification changed the location of the wires coming out of the servo, so the bracket would no longer fit. It is possible to permanently modify the bracket to work by cutting a notch out of it with a rotary tool or a pair of diagonal cutters, but do so at your own risk as it could damage the bracket.

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

Comparison to the Power HD 3001HB servo

The FS5103B is a lower-cost alternative to the 3001HB from Power HD, which has nearly identical dimensions and similar performance. The two servos should be generally interchangeable for most applications. The picture below shows both the FS5103B and the 3001HB side by side:

General specifications

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