E8T Miniature Optical Kit Encoder

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  • Push-on hub - spring loaded collet design
  • Minimum shaft length of .295"
  • Fits shaft diameters of .118" to .375"
  • 180 to 720 cycles per revolution (CPR)
  • 720 to 2,880 pulses per revolution (PPR)
  • Single +5V supply

The E8T transmissive optical encoder is designed to provide digital quadrature encoder feedback for high volume, compact space applications. The E8T is designed to be a drop in replacement for the E7P/E8P that...

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Product Specifications

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

± 12
± 7

Shock, 6 millisecond, half-sine 75 G
Vibration (20Hz to 2kHz, sinusoidal) 20 G


Max. Shaft Axial Play ± .010 in.
Max. Shaft Runout (TIR) .002 in.
Max. Acceleration 250000 rad/sec²

Maximum RPM (1)
e.x. CPR = 500, max. rpm = 12000
e.x. CPR = 200, max. rpm = 30000

minimum value of
and (60000)
Codewheel Moment of Inertia 1.789 x 10^-6 oz-in-s²
Mounting Screw Size
Default (D-option), 1.28" base (G-option)
Metric (M-option)

#4-40, length 0.188"
M2.5, length 5mm
Screw Bolt Circle Diameter
Default (D-option), Metric (M-option)
1.28" base (G-option)

.75 ±.005
1.28 ±.005

Minimum Shaft Length (2) .295 in.
Maximum Shaft Length (2) .400 (D option) /
no limit (H option) 
Mounting Screw Torque 2-3 in-lbs
Technical Bulletin TB1001 - Shaft and Bore Tolerances Download

(1) 60000 RPM is the maximum rpm due to mechanical considerations. The maximum RPM due to the module's 100kHz maximum output frequency is (6000000/CPR).

(2) Including axial play.


Supply Voltage 4.5 5.0 5.5 V  
Supply Current   25 30 mA no load
Low-level Output     0.4 V IOL = 8 mA
  0.035   V no load
High-level Output 2.4     V IOH = -8 mA
  4.0   V no load
Output Rise Time   100   ns no load
Output Fall Time   50   ns no load
Supply Voltage 4.5 5.0 5.5 V  
Supply Current   27 32 mA no load
Differential Output Voltage High 4.75 5.0   V Min. @ 25mA load, Typ. @ no load
Differential  Output Voltage Low   0.25 0.60 V Typ. @ no load, Max. @ 4.5mA load
Differential Output Voltage 3.0 3.8   V RL = 100 ohm
Differential Output Rise/Fall Time     20 ns


Symmetry, S 105 180 255 electrical degrees
Quadrature Delay, Q 30 90 150 electrical degrees

(1) A leads B for clockwise shaft rotation, B leads A for counter clockwise shaft rotation viewed from the cover 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.

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

H-option (Hole In Cover)

The H-option adds a 0.425" diameter hole in the cover for the shaft to pass through.

M-option (Metric Mounting Screws with Default base)

Provides metric M2.5, length 5mm screws. When M-option is NOT specified the default is #4-40, length 0.188" screws. The mounting bolt circle diameter is 0.75" 

G-option (1.28" diameter bolt circle mount)

Provides 1.28" diameter bolt circle mount in addition to 0.75" diameter bolt circle mount. Screws are #4-40, length 0.188"

1. Centering Tool*

Part #: CTOOL - (Shaft Diameter)
Description: This reusable tool is used to accurately center the E8T base on the shaft.

2. Spacer Tool*

Part #: SPACER-E8T
Description: This reusable tool is used to properly gap the codewheel from the encoder sensor.


*Both the CTOOL and SPACER-E8T tools are included with all packaging options.

Updated PCB on the US Digital E8T - PCN 6514 5/16/2018 This notice is to inform our customers of a PCB design change that is being implemented for the entire E8T product line. As part of our continuous improvement objective, the new PCB will improve overall product performance and enhance robustness of this product line. The new PCB has two mounting holes that mate with the base plate instead of one hole and one slot. This change has no impact on form, fit or function for the E8T. Download
E4T, S4T and E8T Laser Markings - PCN 6227 8/8/2017 This notification is to inform our customers of a change to product markings for the E4T, E8T, and S4T series of encoders. The new marking will be utilized across all three product lines. We are making this change to improve readability for our customers and to provide consistency across the product lines.

Product Description

Restriction of Hazardous Substances

The E8T transmissive optical encoder is designed to provide digital quadrature encoder feedback for high volume, compact space applications. The E8T is designed to be a drop in replacement for the E7P/E8P that offers higher maximum speed and increased output drive. The E8T utilizes an innovative, push-on codewheel which accepts shaft diameters of .118" to .375".

The E8T default encoder base provides mounting holes for two #4-40, length 0.188" or two M2.5, length 5mm screws on a 0.75" bolt circle diameter. A 1.28" diameter bolt circle mount is also available, only with #4-40, length 0.188" screws. The encoder cover is easily snapped onto the base and is marked with the connector pin-out.      

The single-ended output version is connected using a 4-conductor, high retention, polarized, 1.25mm pitch connector. The differential output version uses a similiar 6-pin connector. Mating cables and connectors (see the Cables / Connectors web page) are not included, and are available separately.    


Cable/connector assembly not included and must be ordered separately.

Related Products & Accessories

Product Configuration

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1. CPR
2. Bore
3. Output

4. Cover

5. Base

6. Packaging

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For purchasing or volume discounts, please use the above part number and contact us at:

sales@usdigital.com or

800.736.0194 (Toll Free)
360.260.2468 (Local)