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Technical Specifications
Last Updated: 2026-09-08Identity
Performance
Physical
Drivetrain
Control & Signal
Electrical & Environment
Connectivity
Origin
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| Identity | |
| Brand |  |
| Product Number | JRPS821 |
| Category | Hobby |
| Discontinued | Yes |
| Performance | |
| Torque |
6.0V
88.00 oz-in
6.34 kg-cm
0.6 N-m
4.8V
72.00 oz-in
5.18 kg-cm
0.5 N-m
|
| Speed |
6.0V
0.15 sec/60°
400.0 deg/s
66.7 RPM
4.8V
0.19 sec/60°
315.8 deg/s
52.6 RPM
|
| Running Current | (add) |
| Stall Current | 0.93–1.09 A930–1090 mA |
| Physical | |
| Weight | 1.50 oz42.5 g |
| Dimensions |
L 1.50 in W 0.74 in H 1.47 in L 38.1 mm W 18.8 mm H 37.3 mm |
| Case Material | Plastic |
| Drivetrain | |
| Motor Type | 3-pole |
| Motor Drive | (add) |
| Gears | Nylon |
| Gear Spline/Teeth | 23 T estimate |
| Shaft Size | (add) |
| Rotation Mode | Positional |
| Rotation/Support | Single Bearing |
| Backlash | (add) |
| Control & Signal | |
| Modulation | Digital |
| Direction | (add) |
| Rotational Range | (add) |
| Mechanical Limit | (add) |
| Pulse Cycle | (add) |
| Pulse Width | 1000-2000 µs |
| Neutral Position | 1500 µs |
| Dead Band | (add) |
| Refresh Rate | (add) |
| Angle Sensor | Potentiometer |
| Control System | PWM |
| Programmable | No |
| Signal Voltage | (add) |
| Electrical & Environment | |
| Operating Voltage | 4.8–6 V |
| Power Source | Direct |
| Regulator Type | Direct |
| Temperature | (add) |
| Water Rating | (add) |
| Certification | CE |
| Idle Current | (add) |
| Connectivity | |
| Connector | JR (Universal) |
| Wire Length | (add) |
| Origin | |
| Country of Origin | (add) |
Disclaimer: Most data is sourced from the manufacturer. Some data is sourced from our loyal community and with the help of AI. We aim for accuracy but are not responsible for inaccurate information.
Performance Analysis
| Shaft Power | 0.70–1.08 W |
| Torque Density | 1.6941 oz-in/g Stronger than 17% of the 831 Digital Standard servos in the database |
| Torque-to-Volume Ratio | 44.13 oz-in/in³ Denser torque than 13% of the 842 Digital Standard servos in the database |
| Power Density | 0.665 W/in³ More power-dense than 8% of the 1643 Digital Standard servos in the database |
| Speed-to-Weight | 0.12384 (1/sec·g) Faster than 54% of the 820 Digital Standard servos in the database |
| Speed-Torque Trade-off | 13.68 Better balanced than 25% of the 825 Digital Standard servos in the database |
| Current-per-Torque Ratio | 0.0151 A/oz-in More efficient than 52% of the 230 Digital Standard servos in the database |
| Torque Gain per Volt | 18.52%/V More voltage-responsive (torque) than 71% of the 672 Digital Standard servos in the database |
| Speed Gain per Volt | 22.22%/V More voltage-responsive (speed) than 87% of the 686 Digital Standard servos in the database |
| Voltage Range Width | 1.2 V Wider voltage range than 22% of the 1268 Digital Standard servos in the database |
| Dead-Band-to-Pulse-Width Ratio | 0.0000 1st-highest dead-band-to-pulse-width ratio of 326 Digital Standard servos |
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Reviews (6)
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Jaden Lobbia
June 7, 2021Application(s): Thunder Tiger Raptor 30 V2
Comments: Used as my cyclic servos, and for my collective. When rebuilding the output gear on the collective servo broke clean off. I don't know if it's user error or not.
Russ
May 3, 2019Application(s): Sig Kadet Mark II w/OS 46LA
Comments: I lost my plane on the 3rd flight , doing a Loop with a Snap Roll on Top ,, lost the Elevator 75% of the way thought the loop and it flow in to the ground .. Out put shaft of the DS821 snapped , I used NO lock Tight or any thing else on it Will never use a DS821 ever again
Joel
December 8, 2014Application(s): All around except throttle, OMP Yak
Comments: First servos I ever bought, six plus years now, sent them in a year ago and they all checked out fine. Recently bought more to replace Hitecs, my 5245 jammed and crashed my plane, no more Hitec for me.
Jimmy
November 22, 2014Application(s): Seagull Edge 540, OS120, throttle servo
Comments: I lost a nice Seagull edge 540 when the throttle servo
gears jamed and it pulled the battery voltage down
to 3.5v, causing the other servos to wander around
aimlessly. I wouldn't recomend this servo on anything.
I'm also switching to Hitec servos in the future.Duckby
January 4, 2012Application(s): Extra 330 68" span all EX rudder
Comments: good nice servo for the price NEVER USE THREAD LOCK it kills the gears. good sports servo not doing 3D so no need for silly fast speeds. done 50 flights with them now with no problems and still tight..
artgorgeous
March 3, 2010Application(s): for my invention
Comments: Very good servo. Powerful and fast.