Magnetic Encoder Pair Kit (Side-Entry JST SH) for Micro Metal Gearmotors • 12 CPR • 2.7–18V

Upgrade your micro metal gearmotors into “smart motors” with real feedback. The Pololu 4761 kit adds quadrature encoders using a magnetic disc + Hall sensors—ideal for RPM control, distance tracking (odometry), and closed-loop robotics. This version uses a neat side-entry 6-pin JST SH connector so you can use removable cables (motors and cables sold separately).

Output-shaft counts per revolution = gear ratio × 12. (Example: 100:1 gearbox → 1200 counts per output rev.)

Compatibility (important)

Extended back shaft required (dual-shaft micro metal gearmotor version).
Fits within the motor’s 12 mm × 10 mm cross section on 3 sides; extends about 4.2 mm on the 4th side.
The assembled encoder extends about ~5 mm beyond the plastic motor end cap.

Install note: The encoder board is meant to be soldered to the back of the motor. Avoid prolonged heating of motor pins (to prevent deforming the motor’s plastic end cap/brushes). If you want “no-solder,” consider getting a motor that already includes an encoder.

Why/Benefits

Closed-loop ready: read speed + direction with quadrature A/B signals for PID control.
Wide voltage support: sensors run from 2.7V to 18V; A/B outputs are digital signals.
Cleaner wiring: JST SH connector lets you use removable cables (great for servicing and modular builds).
Reliable transitions: built-in hysteresis helps prevent spurious transitions when the motor stops near an edge.

Technical specifications

Model	Magnetic Encoder Pair Kit (Side-Entry JST SH)
Compatibility	Micro metal gearmotors with extended back shafts (required)
Encoder type	Dual-channel Hall sensors + 6-pole magnetic disc (quadrature)
Resolution	12 counts per revolution of motor shaft (counting both edges of both channels)
Output shaft CPR	Output CPR = (gear ratio) × 12
Operating voltage	2.7V to 18V
Connector	Side-entry, 6-pin male, JST SH-type
Size / weight	14.2 mm × 11.6 mm; 1.5 g (full set)
Kit contents	2× encoder boards + 2× magnetic discs (motors & cables not included)

Pinout & power notes

M1 / M2: motor leads (pass-through via the 6-pin cable).
VCC / GND: powers the sensors (2.7–18V).
A / B: quadrature outputs. Signals are driven low or pulled up to VCC through onboard 10k pull-ups.
Tip: For 3.3V microcontrollers (ESP32/RP2040), power VCC at 3.3V so A/B are 3.3V-safe.

FAQ

Will this work on standard micro metal gearmotors?

It requires the extended back shaft version (dual-shaft). It won’t fit standard single-shaft motors.
How do I compute counts per revolution at the gearbox output?

Multiply your gear ratio by 12. Example: 50:1 → 600 counts per output revolution.
Do cables come with the kit?

No—this kit is the encoder boards + magnetic discs only. Add a compatible 6-pin JST SH cable separately.

Magnetic Encoder Pair Kit with Side-Entry Connector for Micro Metal Gearmotors, 12 CPR, 2.7-18V

Name: Magnetic Encoder Pair Kit with Side-Entry Connector for Micro Metal Gearmotors, 12 CPR, 2.7-18V
Brand: circuitrocks
SKU: POL4761
Price: 669.0 PHP
Availability: InStock