FT5121M High-Torque, High-Voltage Digital Servo
The FT5121M is a standard-size digital servo from FEETECH that can deliver over three times the torque of our standard-size servos with plastic gears thanks to its powerful coreless motor and all-metal gear train (if you need even more torque than this, check out the larger FT5335M giant servo, which can deliver 550 oz-in at 7.4 V, and if you need more speed in a servo with the same dimensions as the FT5121M, consider the FT5313M). The output shaft is supported by two ball bearings for reduced friction.
The FT5121M works with standard RC servo pulses, providing a running angle of approximately 120° over a servo pulse range of 900 µs to 2100 µs. Many hobby servos can be operated beyond their standard ranges by using a wider pulse range, but please note that in our tests, we were not able to expand the range of the FT5121M significantly beyond 120° (the servo did not respond to pulses below around 800 µs or above around 2100 µs, providing an approximate expanded range of 135°).
This servo has a 10″ (25 cm) cable that is terminated with a standard JR-style connector, which is Futaba-compatible. Unlike typical hobby servos, the FT5121M has an operating voltage of 6 V to 7.4 V.
The picture below shows the all-metal gear train that helps the servo deliver such high torque:
Note that, as with most hobby servos, stalling or back-driving this servo can damage it. This servo can draw bursts of current in excess of 5 A at 7.4 V, so please make sure you have an appropriate power supply. For comparison, a typical standard-size servo might draw around an amp when straining.