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Technical Specifications
Last Updated: 2026-10-08| Identity | |
| Brand |  |
| Product Number | HD-3688HB |
| Category | Hobby |
| Discontinued | Yes |
| Performance | |
| Torque |
6.0V
38.89 oz-in
2.80 kg-cm
0.3 N-m
4.8V
27.78 oz-in
2.00 kg-cm
0.2 N-m
|
| Speed |
6.0V
0.07 sec/60°
857.1 deg/s
142.9 RPM
4.8V
0.08 sec/60°
750.0 deg/s
125.0 RPM
|
| Physical | |
| Weight | 0.88 oz25.0 gAverage |
| Dimensions |
L 1.378 in W 0.591 in H 1.181 in L 35.0 mm W 15.0 mm H 30.0 mm |
| Drivetrain | |
| Motor Type | 3-pole |
| Gears | Metal |
| Gear Spline/Teeth | 25 T estimate |
| Rotation/Support | Dual Bearings |
| Control & Signal | |
| Modulation | Digital |
| Rotational Range | 154° |
| Pulse Cycle | 3 ms |
| Pulse Width | 800-2200 µs |
| Connectivity | |
| Connector | JR (Universal) |
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.
Class Comparison
| Weight | Average Lighter than 57% of 466 Digital Mini servos |
Performance Analysis
| Shaft Power | 0.64–1.03 W |
| Power Density | 1.068 W/in³ More power-dense than 22% of 440 Digital Mini servos |
| Torque Density | 1.1112 oz-in/g |
| Torque-to-Volume Ratio | 28.88 oz-in/in³ |
| Speed-to-Weight | 0.50000 (1/sec·g) |
| Speed-Torque Trade-off | 2.22 |
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Reviews (7)
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Arnold_NL
August 20, 2013Application(s): Tail servo for 450 Pro
Comments: Used and still using this servo on my 2 year old CX450 Pro with a Spartan-RC DS760 gyro without any problems. Running on 4.8V
gyro set to 1520usec/333Hz with 0.07usec/60degreesManuel
July 31, 2013Application(s): HK 450 Pro
Comments: Me duro unos 15 vuelos, después se me rompió sin aviso ninguno, suerte que fue a 15 cms del suelo. Se calentaba un montón y no me fiaba un pelo, no lo recomiendo para nada...
450ProGuy
July 3, 2013Application(s): Tail servo for 450 Pro.
Comments: Died in flight, luckily just on lift off so no damage... Worked fantastically before that, but alas...
Morad
April 11, 2012Application(s): Trex 450 Tail Servo - used with Detrum GY48v Gyro
Comments: I have this installed on 6 helis. On two so far I have experience failures, luckinly not in flight. Just like every said above, they work great and all of a sudden then start acting up and die. Nice package and nice looks but frankly for teh price (not cheap at $25!) they are not worth it.
Steve
September 24, 2011Application(s): Tail rotor servo in an EXI 450.
Comments: Performed perfectly up until the point where it mysteriously died for no reason. Was running at 6V, died after about 30 flights or so. Still powers up and holds center, but will not accept signal inputs.
Elms
September 18, 2011Application(s): 500 heli tail servo.
Comments: Also died in flight without warning sinse 6 flights. Caused bad crash. Until death works perfect. :(((
Sun Valley
June 15, 2011Application(s): 450 Pro Helicopter
Comments: Used this servo on the tail of my 450 Pro Heli. Worked great for about two months and died in flight without warning. Running 4.8volts. I cannot recommend this servo. Beware!