Comparison table
| Unit | Price | Torque | Speed | Weight | Status |
|---|---|---|---|---|---|
| TowerPro SG90 | $2 – $5 | 0.18 N·m | 0.10 s/60° at 4.8 V | 9 g | Available |
| TowerPro MG90S | $3 – $5 | 0.18 N·m | 0.10 s/60° at 4.8 V | 13.4 g | Available |
| EMAX ES08MA II | $11.94 | 0.16 N·m | 0.12 s/60° at 4.8 V | 12 g | Available |
| TowerPro MG996R | $4 – $8 | 0.92 N·m | 0.19 s/60° at 4.8 V | 55 g | Available |
| DSServo DS3218 (20 kg) | $12 – $25 | 1.86 N·m | 0.16 s/60° at 5 V | 60 g | Available |
| Hitec HS-422 Deluxe | $20.99 | 0.32 N·m | 0.21 s/60° at 4.8 V | 45.5 g | Available |
| Hitec HS-645MG | $43.99 | 0.76 N·m | 0.24 s/60° at 4.8 V | 55.2 g | Available |
| Hitec HSR-8498HB | about $26 | 0.73 N·m | 0.20 s/60° at 6 V | 54.7 g | Discontinued |
| Futaba S3003 | $11 | 0.31 N·m | 0.23 s/60° at 4.8 V | 37 g | Discontinued |
| Savox SC-1256TG | $85 – $99 | 1.57 N·m | 0.18 s/60° at 4.8 V | 52.4 g per ServoCity. Savox's… | Available |
| goBILDA 2000 Series Dual Mode Servo (25-2, Torque) | $36.99 | 1.69 N·m | 0.25 s/60° | 60 g | Available |
| FEETECH FS90R (continuous rotation) | $9.82 | 0.13 N·m | 100 rpm no load at 4.8 V | 9 g | Available |
| Petoi P1S alloy servo (and Lite plastic servo) | $119.99 – $179.00 per 10-servo set | 0.29 N·m | 0.07 s/60° | 14 g | Available |
TowerPro SG90
Typical per-unit price in multi-packs on Amazon US, October 2026 check (e.g. 4 for $7.98, 10 for $19.99, 2 for $4.99). Most of these listings are unbranded clones, not Tower Pro units. Tower Pro's own site lists no price.
The 9 g blue micro servo is the most common actuator in hobby robotics and the reference point every other micro servo is compared to. Tower Pro still makes it, but the name has become generic and most units sold online are clones whose torque, centering and dead band differ from the datasheet. Tower Pro's current product page labels it a digital servo, but the original version sold for years, and most clones, are analog.
- Torque
- 0.18 N·m (1.8 kg·cm) stall at 4.8 V
- Speed
- 0.10 s/60° at 4.8 V
- Weight
- 9 g
- Size
- 23 × 12.2 × 29 mm
- Voltage
- 4.8 V per Tower Pro. Clone datasheets commonly list 4.8–6 V (unconfirmed).
- Current
- about 0.5–2 A operating (Tower Pro figure, given in a Q&A reply on the product page)
- Gearing
- POM (acetal plastic) gear set
- Motor
- brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM (50 Hz pulse), JR-style 3-pin plug (fits JR and Futaba), 25 cm lead
- Range
- about 180° (not stated by Tower Pro, unconfirmed)
- Other
- dead band 1 µs (maker figure). Operating temperature 0–55 °C.
Very light loads, learning PWM control, pan-tilt heads and small 3D-printed builds where a stripped gear costs only a couple of dollars to replace.
Walking robots that carry real weight or any joint that gets back-driven, since the plastic gears strip easily and clone quality varies widely.
Robots in the guide that use it
The default servo of countless Arduino starter kits, pan-tilt camera mounts, small 3D-printed arms and grippers.
Sources Tower Pro SG90 product page ↗ · Amazon US search (clone listings) ↗
Buying Amazon US Prime listings deliver in 1–2 days. AliExpress and similar sellers take 1–3 weeks (unconfirmed).
TowerPro MG90S
Typical per-unit price in packs on Amazon US, October 2026 check (2 for $8.88, 4 for $13.88, 10 for $28.99). Most listings are clones. Vorpal Robotics sells a Tower Pro-made 'Vorpal MG90' for $9.99 (unconfirmed).
The metal-gear version of the SG90 in the same 9 g class footprint, and the usual upgrade when SG90 gears strip. It powers the 12 legs of the Vorpal hexapod and the eight legs of the open-source Sesame walker. Like the SG90, the name is widely cloned and quality ranges from close to the datasheet to noticeably weaker.
- Torque
- 0.18 N·m (1.8 kg·cm) stall at 4.8 V, 0.22 N·m (2.2 kg·cm) at 6.6 V
- Speed
- 0.10 s/60° at 4.8 V, 0.08 s/60° at 6 V
- Weight
- 13.4 g
- Size
- 22.8 × 12.2 × 28.5 mm
- Voltage
- 4.8 V nominal per Tower Pro, with a torque figure given at 6.6 V
- Gearing
- metal (aluminum 6061-T6 gears and shaft per maker)
- Motor
- brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM (50 Hz pulse), JR-style 3-pin plug, 25 cm lead
- Range
- about 180° (not stated by Tower Pro, unconfirmed)
- Other
- dead band 1 µs (maker figure). Same footprint as the SG90, so it drops into SG90 mounts. Tower Pro's page also labels it a digital servo.
Small legged robots and arms that need an SG90-sized servo which survives shock loads and being pushed by hand.
Precise or quiet motion, since clones often jitter and have loose centering, and torque is still only about 2 kg·cm.
Robots in the guide that use it
Also common in small 3D-printed hexapods and quadrupeds, robot grippers and many Arduino arm kits.
Sources Tower Pro MG90S product page ↗ · Vorpal Combat Hexapod (Hackaday.io, lists 12 × MG90S) ↗ · Amazon US search (clone listings) ↗
Buying Amazon US Prime listings deliver in 1–2 days. AliExpress 1–3 weeks (unconfirmed).
EMAX ES08MA II
EMAX official store, October 2026 check. RaceDayQuads lists it at $13.49. GetFPV and TotsRC also stock it (prices unconfirmed).
EMAX's 12 g metal-gear analog micro servo, slightly heavier than an MG90S with similar torque. It is popular because EMAX is a known brand with consistent quality, and it sells for only a little more than generic MG90S units. EMAX also makes a digital sibling, the ES08MD II.
- Torque
- 0.16 N·m (1.6 kg·cm) at 4.8 V, 0.20 N·m (2.0 kg·cm) at 6 V
- Speed
- 0.12 s/60° at 4.8 V, 0.10 s/60° at 6 V
- Weight
- 12 g
- Size
- 23 × 11.5 × 24 mm
- Voltage
- 4.8–6 V
- Current
- 200 mA working (reseller spec table)
- Gearing
- metal gears
- Motor
- brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM, analog, Futaba/JR universal plug, 25 cm lead
- Other
- Sold in normal and reverse-rotation versions. A digital ES08MD II also exists. An HV version (ES08MA II HV) is reported (unconfirmed).
Small robots and grippers that want metal gears from a branded maker with consistent quality, unlike most unbranded clones.
Higher loads or 2S LiPo power without a regulator, since it is rated only up to 6 V and about 2 kg·cm.
A common branded alternative to MG90S clones in small robot arms, grippers and RC aircraft.
Sources EMAX official store ↗ · RaceDayQuads listing (spec table) ↗
Buying Sold by US FPV shops (RaceDayQuads, GetFPV, TotsRC) that ship domestically. EMAX's own store shipping time unconfirmed.
TowerPro MG996R
Typical per-unit price in packs on Amazon US, October 2026 check (6 for $21.99, 4 for $18.99, 2 for $13.98). Nearly all are clones (Deegoo-FPV, Aideepen and unbranded). Tower Pro's own site lists no price.
The default cheap standard-size metal-gear servo, the successor to the MG995. It is everywhere in budget robot arm kits, but its reputation is mixed because most units sold are clones with sloppy centering, a wide dead band and inconsistent torque. Builders of legged robots usually move up to 20 kg-class servos such as the DS3218.
- Torque
- 0.92 N·m (9.4 kg·cm) stall at 4.8 V, 1.08 N·m (11 kg·cm) at 6 V
- Speed
- 0.19 s/60° at 4.8 V, 0.15 s/60° at 6 V
- Weight
- 55 g
- Size
- 40.7 × 19.7 × 42.9 mm
- Voltage
- 4.8–6.6 V
- Current
- idle 10 mA, no-load 170 mA, stall 1.4 A
- Gearing
- metal gears
- Motor
- brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM (50 Hz pulse), JR-style 3-pin plug (fits JR and Futaba), 32 cm lead
- Range
- about 180° (not stated by Tower Pro, unconfirmed)
- Other
- dead band 1 µs (maker figure). Standard-size servo with 25-tooth output spline (unconfirmed).
Cheap standard-size joints in arms and kits where a few kg·cm is enough and units can be swapped when one fails.
Legged robots that need consistent torque and holding precision, since clone units vary widely, buzz under load and often fall short of the rated torque.
The standard servo in the SpotMicroAI quadruped parts list (12 per robot, with the CLS6336HV as the suggested upgrade). Very common in cheap 6-DOF aluminum arm kits, pan-tilt brackets and student robots.
Sources Tower Pro MG996R product page ↗ · SpotMicroAI parts list (12 × MG996R) ↗ · Amazon US search (clone listings) ↗
Buying Amazon US Prime listings deliver in 1–2 days. AliExpress 1–3 weeks (unconfirmed).
DSServo DS3218 (20 kg)
October 2026 check. Amazon US single and multi-pack DS3218-type listings work out to roughly $12–$14 each, RCDrone lists the DSServo unit at $24.81. The faster DS3218 PRO is about $18 (ItGresa, unconfirmed).
The DS3218 is a widely used budget high-torque servo, giving roughly twice the torque of an MG996R in the same standard case for a similar or slightly higher price. Its metal gears and aluminum case make it the usual upgrade for SpotMicro-style quadrupeds. The design is sold under many brand names, so quality varies by seller. DSServo also makes a faster DS3218 PRO.
- Torque
- 1.86 N·m (19 kg·cm) stall at 5 V, 2.11 N·m (21.5 kg·cm) at 6.8 V
- Speed
- 0.16 s/60° at 5 V, 0.14 s/60° at 6.8 V
- Weight
- 60 g
- Size
- 40 × 20 × 40.5 mm
- Voltage
- 4.8–6.8 V
- Current
- idle 4 mA at 5 V and 5 mA at 6.8 V, stall about 2.2 A at 6.8 V (unconfirmed)
- Gearing
- copper and aluminum (metal) gears
- Motor
- brushed DC (iron-core)
- Feedback
- none to the controller, internal potentiometer only
- Interface
- digital RC PWM, 1520 µs center, up to 333 Hz frame rate, 25T output spline
- Range
- 180° or 270° versions
- Other
- aluminum middle case, IP66 water resistance claimed, dead band 3 µs. DS3218 PRO version rated 21/23.5 kg·cm and 0.12/0.10 s/60° at 5/6.8 V.
Budget legged robots and arms that need about 20 kg·cm per joint for $12–$25 a servo.
Robots that need position feedback or smooth compliant motion, and setups without a stout 5–7 V supply, since a dozen of them can pull well over 20 A when stalled.
Widely used in community SpotMicro builds and other 3D-printed quadrupeds, robot arms and RC crawlers (unconfirmed for any specific official design).
Sources DSServo official DS3218 product page (specs as images) ↗ · DSServo DS3218 datasheet download page ↗ · RCDrone DSServo DS3218 listing (spec table) ↗ · Servo Database DS3218 PRO ↗ · Amazon US search ↗
Buying Amazon US Prime listings deliver in 1–2 days. RCDrone and AliExpress ship from China in 1–3 weeks (unconfirmed).
Hitec HS-422 Deluxe
Hitec RCD USA store, October 2026 check. Replacement nylon gear set (shared with the HS-425BB) $5.47 on Hitec's gear-set page.
One of Hitec's oldest and most familiar standard servos, still sold new by Hitec with spare gear and case sets. It is a plain analog servo with nylon gears, so its value today is consistency and spare-part availability rather than performance. Cheap 20 kg digital servos now beat it on torque for the same price.
- Torque
- 0.32 N·m (3.3 kg·cm) at 4.8 V, 0.40 N·m (4.1 kg·cm) at 6 V
- Speed
- 0.21 s/60° at 4.8 V, 0.16 s/60° at 6 V
- Weight
- 45.5 g
- Size
- 40.6 × 19.8 × 36.6 mm
- Voltage
- 4.8–6 V
- Current
- idle 8 mA, no-load 150 mA, stall 800 mA
- Gearing
- nylon gears, dual Oilite bushings, 24T output spline
- Motor
- 3-pole ferrite brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM, analog circuit (HT7003)
- Other
- dead band 8 µs. Plastic case. Two-year limited warranty.
Light standard-size joints where a known, consistent brand matters more than torque, such as pan-tilt heads and small arm wrists.
Loaded legs or shoulders, since it has nylon gears and only about 4 kg·cm.
A long-time default in Lynxmotion arm and hexapod kits and many university robotics courses (unconfirmed).
Sources Hitec RCD HS-422 product page ↗ · Hitec RCD gear sets (HS-422 / HS-425BB nylon gear set) ↗
Buying Hitec RCD sells direct from its US store, and US hobby retailers stock it. Shipping times not stated (unconfirmed).
Hitec HS-645MG
Hitec RCD USA store, October 2026 check. Replacement metal gear set $21.97 on Hitec's gear-set page.
Hitec calls the HS-645MG its most popular servo, and it was the workhorse of hobby robot arms and hexapods through the 2000s and 2010s. It is still an analog servo with modest torque by today's standards, but it remains in production with replacement gear and case sets. Hitec sells the same servo with a 25-tooth spline as the HS-648MG.
- Torque
- 0.76 N·m (7.7 kg·cm) at 4.8 V, 0.94 N·m (9.6 kg·cm) at 6 V
- Speed
- 0.24 s/60° at 4.8 V, 0.20 s/60° at 6 V
- Weight
- 55.2 g
- Size
- 40.6 × 19.8 × 37.8 mm
- Voltage
- 3.5–6.8 V (2S LiFe)
- Gearing
- 1 metal-plastic hybrid plus 3 metal gears, dual ball bearings, 24T spline
- Motor
- cored (iron-core) brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM, analog
Standard-size robot joints that need metal gears, ball bearings and a well-documented brand with spare parts.
Budget builds, since DS3218-class servos offer about twice the torque for under half the price, and anything needing position feedback.
Long used in Lynxmotion arms and hexapods and many research and hobby legged robots (unconfirmed).
Sources Hitec RCD HS-645MG product page ↗ · Hitec RCD gear sets, page 2 (HS-645MG metal gear set) ↗
Buying Hitec RCD sells direct from its US store, and US hobby retailers stock it. Shipping times not stated (unconfirmed).
Hitec HSR-8498HB
No longer sold by Hitec RCD USA (October 2026 check). An AliExpress listing showed about $25.80 (unconfirmed). Electrokit (Sweden) marks it as a product that has left its range.
Hitec made the HSR-8498HB specifically for the ROBONOVA-I, one of the first affordable kit humanoids, in the mid-2000s. Beyond normal PWM control it spoke Hitec's HMI protocol, which let the controller read back joint positions so poses could be taught by moving the robot by hand. It was an early step from plain hobby servos toward today's smart serial servos.
- Torque
- 0.73 N·m (7.4 kg·cm) stall at 6 V (Hitec datasheet). 0.88 N·m (9.0 kg·cm) at 7.4 V per Servo Database, a voltage Hitec's datasheet does not list.
- Speed
- 0.20 s/60° at 6 V (Hitec datasheet). 0.18 s/60° at 7.4 V per Servo Database.
- Weight
- 54.7 g
- Size
- 40 × 20 × 37 mm (Hitec datasheet)
- Voltage
- 6 V (Hitec datasheet). Electrokit and Servo Database list 6–7.4 V.
- Current
- idle 8 mA, no-load 200 mA, stall 1.2 A at 6 V
- Gearing
- Karbonite (heavy-duty resin) gears, dual MR106 ball bearings, 24-segment output spline
- Motor
- cored brushed DC (3-pole per Servo Database)
- Feedback
- position readback over Hitec's HMI serial protocol (unconfirmed, not described in the datasheet)
- Interface
- standard RC PWM, 1500 µs neutral, 400 mm 22 AWG lead. Hitec's HMI protocol for position feedback and settings (unconfirmed).
- Range
- Hitec's datasheet gives 45° ± 5° of travel each side of center for standard pulses. Electrokit lists 180°, and some users report about 120° with plain RC pulses (unconfirmed).
- Other
- programmable digital amplifier with MOSFET drive, dead band 5 µs, operating temperature −20 to +60 °C, bottom axial mounting hole
Repairing or restoring a ROBONOVA-I or similar humanoid of that era.
New designs, since it is discontinued and modern serial bus servos offer feedback, higher torque and daisy-chained wiring for less money.
Built for Hitec's ROBONOVA-I humanoid (16 servos per robot). Also used in other small humanoids of the mid-2000s (unconfirmed).
Sources Hitec HSR-8498HB datasheet (PDF, May 2005, hosted by Electrokit) ↗ · Servo Database HSR-8498HB (specs, discontinued) ↗ · The Old Robots, Hitec ROBONOVA-I ↗ · Electrokit listing (product left the range) ↗
Buying Not sold new by Hitec. Remaining stock appears on AliExpress (1–3 weeks) and eBay (unconfirmed).
Futaba S3003
October 2026 check. Tower Hobbies lists the S3003 as discontinued. Esprit Model lists it at $11.00 but shows it as 'coming soon' rather than in stock. Futaba USA's own site was unreachable during the check (its listing was reported as discontinued, unconfirmed). Used and new units on eBay go for about $10.50 (unconfirmed).
The S3003 was Futaba's basic standard servo and shipped in radio sets for decades, which made its 40 × 20 mm case the de facto standard size that brackets and kits are designed around. US distributors now list it as discontinued, though remaining stock and the near-identical clones it inspired are still easy to find.
- Torque
- 0.31 N·m (3.2 kg·cm, 44 oz·in) at 4.8 V, 0.40 N·m (4.1 kg·cm, 57 oz·in) at 6 V
- Speed
- 0.23 s/60° at 4.8 V, 0.19 s/60° at 6 V
- Weight
- 37 g (1.3 oz)
- Size
- 40 × 20 × 36 mm
- Voltage
- 4.8–6 V
- Gearing
- all-nylon gears, plastic bushing (unconfirmed)
- Motor
- brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- standard RC PWM, analog
Replacing a worn S3003 in an existing model or kit with the exact same part.
New robots, since its nylon gears and 4 kg·cm are outclassed by cheaper modern servos.
For decades a default servo in RC kits, Boe-Bot-era school robots and countless pan-tilt brackets (which are still sold labeled for 'MG996R S3003').
Sources Tower Hobbies S3003 listing (marked discontinued) ↗ · Esprit Model S3003 listing (specs, $11.00) ↗
Buying Remaining stock from US hobby shops and eBay, availability spotty (unconfirmed).
Savox SC-1256TG
October 2026 check. ServoCity $98.99 (SC1256TGP). Savox's own European store lists the SC-1256TG+ at €74.95 including VAT (about $88). RC Superstore $88.99 and AMain Hobbies $84.99 at an earlier check (unconfirmed). Savox USA's own store showed 'store unavailable'.
A long-running high-end hobby servo, sold since about 2010 (unconfirmed), combining a coreless motor, titanium gears and an aluminum case. It shows what the top of the plain PWM servo market looks like, offering similar torque to a DS3218 but with faster response, better gears and tighter quality control. The current version is the SC-1256TG+, and a Black Edition has also been sold (unconfirmed).
- Torque
- 1.57 N·m (16.0 kg·cm) stall at 4.8 V, 1.96 N·m (20.0 kg·cm) at 6 V
- Speed
- 0.18 s/60° at 4.8 V, 0.15 s/60° at 6 V
- Weight
- 52.4 g per ServoCity. Savox's own page for the TG+ lists 64 g.
- Size
- 40.3 × 20.2 × 37.4 mm (Savox)
- Voltage
- 4.8–6 V
- Current
- idle 5 mA, no-load 100–120 mA, stall 4.0 A at 4.8 V and 5.0 A at 6 V
- Gearing
- titanium gears, dual ball bearings, 25T output spline
- Motor
- coreless brushed DC
- Feedback
- none to the controller, internal potentiometer only
- Interface
- digital RC PWM, 800–2200 µs, 1520 µs center (unconfirmed)
- Range
- 160° max (ServoCity figure)
- Other
- aluminum and composite case (heat sinking), water and dust resistant per Savox. The TG+ revision added soft start and Sanwa SSR compatibility (per Servo Database).
Robots that need a durable, fast standard-size PWM servo with a coreless motor and titanium gears that hold up to shock loads.
Multi-joint robots on a budget, since a dozen cost over $1,000, and no feedback is available at that price where smart servos offer it.
Mostly used in RC cars, crawlers and aircraft. Appears in hobby robot arms and legged builds where a higher-grade PWM servo is wanted (unconfirmed).
Sources Savox official SC-1256TG+ product page ↗ · ServoCity SC1256TGP listing (full spec table) ↗ · Servo Database SC-1256TG+ ↗
Buying ServoCity ships from Kansas, US (unconfirmed), and RC Superstore/AMain stock it in the US. Typical delivery times unconfirmed.
goBILDA 2000 Series Dual Mode Servo (25-2, Torque)
goBILDA store, October 2026 check (SKU 2000-0025-0002).
goBILDA's 2000 Series servo is a staple in FTC robots, valued for its 300° range and the option to reprogram it into a continuous-rotation motor. The 25-2 revision added a steel gear train, more torque and a new top case over the earlier 2000-0025-0001. It fits goBILDA's own ecosystem of servo hubs, brackets and channels.
- Torque
- 1.69 N·m (17.2 kg·cm) stall at 4.8 V, 2.12 N·m (21.6 kg·cm, 300 oz·in) at 6 V, 2.47 N·m (25.2 kg·cm) at 7.4 V
- Speed
- 0.25 s/60° (40 rpm) at 4.8 V, 0.20 s/60° (50 rpm) at 6 V, 0.17 s/60° (60 rpm) at 7.4 V, no load
- Weight
- 60 g
- Voltage
- 4.8–7.4 V
- Current
- no-load 150 mA at 4.8 V to 200 mA at 7.4 V, stall 2.0 A at 4.8 V, 2.5 A at 6 V, 3.0 A at 7.4 V
- Gearing
- 300:1 steel gear train, 25T output spline
- Motor
- brushed DC
- Feedback
- none to the controller, internal 5 kΩ potentiometer only
- Interface
- RC PWM, 500–2500 µs in position mode (900–2100 µs in continuous mode), 3-pin TJC8 connector, 300 mm 22 AWG lead
- Range
- 300° in standard mode, continuous rotation after switching with the goBILDA programmer
- Other
- dead band 4 µs. Switching between position and continuous mode needs the goBILDA 3102 Series Dual Mode Servo Programmer.
Competition and education robots that need a strong servo with a wide 300° range, steel gears and a US supplier with matching brackets and horns.
Lightweight or compact builds, and anything that needs position feedback.
Standard servo of many FIRST Tech Challenge (FTC) robots for claws, wrists and intakes (unconfirmed).
Sources goBILDA 2000 Series Dual Mode Servo (25-2) product page ↗ · goBILDA shipping information ↗
Buying goBILDA ships within the US by FedEx and USPS after 1–2 business days of handling, with USPS Ground Advantage taking 5–10 business days and FedEx next-day or 2-day options available. Ships from Kansas (unconfirmed).
FEETECH FS90R (continuous rotation)
Pololu, October 2026 check (single unit, $9.23 at 5+, $8.16 each at 100+).
A continuous-rotation servo is a hobby servo with the position feedback removed, so the pulse width sets speed and direction instead of angle. The FS90R does this in the SG90 footprint and is sold with matching 21T-spline wheels. It is the simplest way to drive two wheels from a microcontroller, with the trade-off of no speed feedback.
- Torque
- 0.13 N·m (18 oz·in, about 1.3 kg·cm) stall at 4.8 V, 0.15 N·m (21 oz·in, 1.5 kg·cm) at 6 V
- Speed
- 100 rpm no load at 4.8 V, 130 rpm at 6 V
- Weight
- 9 g
- Size
- 22.5 × 12.1 × 23.4 mm
- Voltage
- 4.8–6 V (Pololu rates it at 4.8 V and 6 V). Accepts 3.3 V or 5 V logic-level control signals.
- Current
- no-load 130 mA, stall 800 mA at 6 V
- Motor
- brushed DC
- Feedback
- none, speed and direction are open-loop
- Interface
- RC PWM, 1.5 ms rest point (trim potentiometer), longer pulses turn CCW and shorter pulses turn CW, JR-style plug, 250 mm lead
- Range
- continuous rotation
- Other
- 21T, 4.8 mm output spline. Pololu warns that stalling can damage the motor and gears.
Driving small wheels from a plain servo signal with no separate motor driver, in tiny rovers and classroom robots.
Precise driving or odometry, since there is no encoder and the stop point drifts until the trim pot is adjusted.
Drive wheels for small Arduino and micro:bit rovers and classroom robots.
Sources Pololu FS90R product page ↗ · Pololu FS90R spec table ↗
Buying Pololu ships from its Las Vegas, Nevada headquarters and advertises same-day shipping (delivery times unconfirmed). Also sold on Amazon US (unconfirmed).
Petoi P1S alloy servo (and Lite plastic servo)
Petoi official store, October 2026 check. Alloy set $119.99 without feedback (marked down from $150) or $179.00 with feedback control. Plastic-geared Lite set $84.00 without feedback (marked down from $120) or $144.00 with feedback.
Petoi designed the slim, coreless P1S for the Bittle robot dog, launched on Indiegogo in 2020, where nine of them drive the eight leg joints and the head. It is not a bus servo at all. It takes ordinary PWM like a hobby servo, and only the optional feedback versions add a position line so poses can be taught by moving joints by hand. Brush wear limits life, so Petoi sells 10-servo sets as spares.
- Torque
- 0.29 N·m (3 kg·cm) stall (P1S, voltage not stated, 6–8.4 V range)
- Speed
- 0.07 s/60° (about 143 rpm) (P1S, voltage not stated)
- Weight
- 14 g
- Size
- 30 × 24 × 12 mm
- Voltage
- 6.0–8.4 V
- Current
- 200 mA idle, 1.5 A stall
- Gearing
- P1S metal (alloy) gears. Lite version plastic gears with a mechanical lock-release that slips under excess force
- Motor
- Coreless (brushed)
- Feedback
- Potentiometer. 'With feedback control' versions let the controller read joint position
- Interface
- Ordinary RC-style PWM (500–2500 µs, dead band 2 µs or less), not a serial bus. No ID, no daisy-chaining
- Range
- 270°
- Other
- One ball bearing, 25T spline. Petoi rates life at more than 100 hours of continuous walking
Spares and upgrades for Bittle-class robots, and other tiny legged robots that need fast, slim 270° servos.
Bus-wired multi-joint builds, since it is a plain PWM servo with no ID or daisy-chaining, and its 3 kg·cm torque suits only palm-sized robots.
Robots in the guide that use it
Also used in Petoi's Bittle X and Nybble Q and the Bittle robotic arm extension. The original Nybble is not compatible.
Sources Petoi alloy servo set (P1S specs) ↗ · Petoi Lite servo set ↗
Buying Petoi store lists $5.99 delivery to the US on orders under $200 (free above), estimated 4–7 business days. RobotShop sells the feedback set as an on-demand item (unconfirmed). Dispatch location unconfirmed.