FEETECH FT90R Digital Micro Continuous Rotation Servo

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Pololu item #: 2817
Brand: FEETECH
RoHS 3 compliant


The FT90R is a digital micro servo that has been built by FEETECH specifically for continuous rotation, offering an inexpensive and easy way to get your small turret spinning or miniature robot moving, especially when paired with our 60×8mm wheels designed specifically for this servo. This servo can work with both 5 V and 3.3 V servo signals.

Key specs at 6 V: 135 RPM (no-load), 21 oz-in (1.5 kg-cm), 9 g, CCW rotation for pulse widths above the rest point.

Compare all products in Continuous Rotation Servos or FEETECH Servos.

Pictures

FEETECH FT90R Digital Micro Continuous Rotation Servo.

FEETECH FS90R micro continuous rotation servo with a LEGO Minifigure as a size reference.

An example of hardware included with the FEETECH FS90 and FS90R micro servos. Actual hardware might vary.

60 mm and 40 mm Pololu Wheels for Micro Servo Splines on FEETECH’s FT90R and FS90R micro continuous rotation servos.

FEETECH FT90R Digital Micro Continuous Rotation Servo and FS90R (analog) Micro Continuous Rotation Servo.

Continuous rotation servo size comparison. From left to right: SpringRC SM-S4303R, Power HD AR-3606HB, FEETECH FS5106R, Parallax Feedback 360°, Parallax (Futaba S148), and FEETECH FS90R.




Overview

The FT90R is a micro-sized digital servo that has been built by FEETECH (formerly known as Fitec) specifically for continuous rotation. At 6 V, it has a maximum rotation speed of around 135 RPM (no-load) and can produce up to 21 oz-in (1.5 kg-cm) of torque. The servo can be controlled using a direct connection to a single microcontroller I/O line without any additional electronics, which makes it a great miniature actuator for beginner robotics projects; just throw on a pair of wheels and your robot is ready to roll!

The FT90R continuous rotation servo converts standard RC servo position pulses into continuous rotation speed. The rest point (sometimes called neutral position) is set to 1.5 ms. Pulse widths above the rest point result in counterclockwise rotation, with speed increasing as the pulse width increases; pulse widths below the rest point result in clockwise rotation, with speed increasing as the pulse width decreases.

The servo has a 10″ (250 mm) lead that is terminated with a JR-style connector and includes additional servo horns and mounting hardware. The following picture shows an example of the hardware that might be included (actual hardware could vary):

This robotics servo, which is a digital version of the FEETECH FS90 continuous rotation servo, is compatible with our servo controllers. If you are looking for a similar servo that is capable of limited-range position control as opposed to continuous rotation speed control, consider the FS90, which has identical dimensions, or the Power HD micro servo HD-1900A, which has almost the same weight, speed, and torque as the FS90.

You can find more information about this servo in its datasheet (110k pdf).

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

Wheels

If you want to use this servo as an actuator for your miniature robot, you will need a wheel to go with it. Fortunately, we carry compatible servo wheels for micro servos (21T, 4.8 mm spline):

60 mm and 40 mm Pololu Wheels for Micro Servo Splines on FEETECH’s FT90R and FS90R micro continuous rotation servos.

The 60×8mm wheel allows for a top speed of around 42 cm/s (1.3 ft/s) at 6 V.

Continuous rotation servo comparison

Continuous rotation servo size comparison. From left to right: SpringRC SM-S4303R, Power HD AR-3606HB, FEETECH FS5106R, Parallax Feedback 360°, Parallax (Futaba S148), and FEETECH FS90R.

6 V 4.8 V Weight (g) Size (mm) Direction
vs pulse
(1ms → 2ms)		 Digital? Feed­back? Price
Max speed
(RPM)		 Stall torque
(oz·in)		 Max speed
(RPM)		 Stall torque
(oz·in)
SpringRC SM-S4303R 54 71 43 46 41  41.3 × 20.7 × 40.2  CW→CCW $14.95
SURPLUS SpringRC SM-S4303R 2-Pack 54 71 43 46 41  41.3 × 20.7 × 40.2  CCW→CW $19.95 for a pair of servos
FEETECH FS5106R 95 83 75 67 43  40.8 × 20.1 × 38.0  CW→CCW $15.95
Parallax Feedback 360° 140 35 – – 41  40.0 × 20.0 × 37.2  CW→CCW yes yes $27.99
FEETECH FT90R 135 21 108 18 9  22.9 × 12.1 × 26.5  CW→CCW yes $8.95
FEETECH FS90R 130 21 100 18 9  22.5 × 12.1 × 23.4  CW→CCW $5.95

Dimensions

Size: 22.9 × 12.1 × 26.5 mm
Weight: 9 g

General specifications

Digital?: Y
No-load current @ 6V: 120 mA
Stall current @ 6V: 800 mA1
Speed @ 6V: 135 rpm
Stall torque @ 6V: 21 oz·in1
Speed @ 4.8V: 108 rpm
Stall torque @ 4.8V: 18 oz·in1
Hardware included?: Y
Lead length: 10 in

Notes:

1
Stalling should generally be avoided as it can damage the motor and gears.

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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