S4 Miniature Optical Shaft Encoder

S4 Features

  • Miniature size
  • Low High retention snap-in polarized connector
  • Tracks from 0 to 30,000 cycles/sec
  • Ball bearing option tracks up to 10,000 RPM
  • Wide operating temperatures
  • 100 to 360 cycles per revolution (CPR)
  • 400 to 1,440 pulses per revolution (PPR)
  • 2 channel quadrature TTL squarewave outputs

See more info below

Configure the S4

The S4 has reached its End of Life (EOL) and is no longer available for purchase. See S4T for replacement product information.

The S4 is no longer available for purchase.

The S4 is no longer available for purchase, and has been replaced by our recently released S4T Miniature Optical Shaft Encoder. The S4T is a redesigned, enhanced version of the S4, and is already available for purchase.

S4 Product Description

Restriction of Hazardous Substances

On January 16, 2012, the S4 part number was modified. The S4 optical encoder is now offered with a differential output option; as a result, the S4 part number was changed to accommodate either the single ended or differential output options. The S4 part number also has a place holder added for a possible future index option. The index option is currently not available and there is not a projected date at which it will be made available. The current "Power" option for the S4 was also removed from the part number. The power option is very rarely selected and therefore is being eliminated from the S4 part number.

The S4 miniature optical shaft encoder is a non-contacting rotary to digital converter. Useful for position feedback or manual interface, the encoder converts real-time shaft angle, speed, and direction into TTL-compatible quadrature outputs without index. The encoder utilizes a mylar disk, metal shaft, and bushing or bearing. It operates from a single +5VDC supply.  

The S4 encoder is available with ball bearings for motion control applications, or static drag to feel like a potentiometer for front-panel manual interface.

The reflective sensor incorporates an LED light source and a monolithic photo detector with signal shaping electronics, providing two channel bounceless quadrature TTL outputs.

The S4 can be connected by using a high retention 4 conductor snap-in polarized 1.25mm pitch connector. The mating connector is polarized and should attach smoothly to the encoder; do not force. See below for Cables & Connectors.   

Product Specifications

View here or download the specifications


Vibration (5Hz to 2kHz) 20 G
Operating Temperature -20 to 100 C
Electrostatic Discharge, IEC 61000-4-2
Single-ended (S-option)
Differential (D-option)

± 3
± 15



SpecificationSleeve BushingBall Bearing
Max. Acceleration 10000 rad/sec² 250000 rad/sec²
Max. Shaft Speed 100 rpm 15000 rpm
Max. Shaft Torque 0.5 ±0.2 in-oz (D-option)
0.3 in-oz (N-option)
0.05 in-oz
Max. Shaft Loading 2 lbs. dynamic
20 lbs. static
1 lb.
Bearing Life > 1,000,000 revolutions L10 = (22/Fr)³ *
Where L10 = bearing life in millions of revs, and
Fr = radial shaft loading in pounds
Weight 0.46 oz. 0.42 oz.
Max. Shaft Total Indicated Runout 0.0015 in. 0.0015 in.
Max. Panel Nut Tightening Torque 20 in-lbs 20 in-lbs
Technical Bulletin TB1001 - Shaft and Bore Tolerances Download

* only valid with negligible axial shaft loading.

Phase Relationship


Symmetry, S 180 ± 16 180 ± 75 electrical degrees
Quadrature Delay, Q 90 ± 10 90 ± 60 electrical degrees

(1) B leads A for clockwise shaft rotation, and A leads B for counterclockwise rotation viewed from the shaft side of the encoder.

(2) Typical values represent the encoder performance at typical mounting alignment, whereas the maximum values represent the encoder performance across the range of recommended mounting tolerance.

Single-ended Electrical

Supply Voltage 4.5 5.0 5.5 V  
Supply Current   21 27 mA no load
Low-level Output     0.4 V IOL = 6 mA
High-level Output 2.4     V IOH = -1 mA
Rise Time   500   ns CL = 25 pF, RL = 2.7 kΩ
Fall Time   100   ns

Differential Electrical

Supply Voltage 4.5 5.0 5.5 V  
Supply Current   23 29 mA no load
Differential Output Voltage 3.0 3.8   V RL = 100 ohm
Differential Output Rise/Fall Time     20 ns


4-pin Single-ended (1)6-pin Differential (2)
1 +5VDC power 1 Ground
2 A channel 2 A channel
3 Ground 3 A- channel
4 B channel 4 +5VDC power
    5 B channel
    6 B- channel

(1) 4-pin single-ended mating connector is CON-MIC4
(2) 6-pin differential mating connector is CON-MIC6

Product Change Notifications

Title Date Description Download
E4, E4P, S4 - PCN 5741 05/09/2016 As part of our on-going product lifecycle management process, we have identified products that will be transitioned to an "End-of-Life" status. Products targeted for end-of-life may be available for a last time buy option prior to being made obsolete, however quantities are limited and special requirements may apply.  Download
E4 - E4P - S4 Update - PCN 1014 11/29/2011 We have modifed the E4, E4P and S4 product lines in order to improve the performance and durability of the encoder. Changes include new molds for the plastic base and cover parts with an over-molded bushing in the S4 base, a new SMT connector (compatible with current mating connector), and a modified PCB profile to accommodate the new connector and plastic part modifications. Download

Additional Information

Product Notes

  • For ordering information please see the Compatible Cables / Connectors section above.
  • US Digital® warrants its products against defects in materials and workmanship for two years. See complete warranty for details.

Downloads Available



3D Model Downloads

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    • SolidWorks format
    • IGES format
    • Parasolid format
    • STEP format

    Related Products & Accessories

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