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QDH20 Optical Rotary Encoder

  • Overview
  • Specifications
  • Info & Pricing

About QDH20 Optical Rotary Encoder

Quantum Devices, Inc. Model QDH20 Optical Rotary Encoder provides an improved feedback solution in applications typically using a standard size 20 package. The QDH20 provides encoder feedback in standard industrial mounting configurations with superb mechanical and environmental protection. Outputs consist of a quadrature A & B with reference pulse Z as a standard feature. The output can be configured with either the 5 to 26 volt OL7272 line driver or open collector outputs. The QDH20 features two heavy-duty bearings holding the output shaft, and two more bearings along with an integral flexible spring mount to isolate the working pieces of the encoder from mechanical stresses.

Design Features:

  • 500 kHz fundamental frequency response
  • High operating temperature (100°C)
  • Resolutions up to 5000 lines per revolution direct read
  • Flange and servo mount options
  • Solid shaft sizes up to 10 mm
  • Blind bore sizes up to 0.625″ diameter
  • High noise immunity


  • Motion control feedback
  • Machine control
  • Process control
  • Elevator controls
  • Agricultural machinery
  • Textile equipment
  • Robotics
  • Food processing
  • Conveyors
  • Material handling

Electrical Specifications

Input Voltage 4.75 to 26 VDC
Input Current Requirements 70mA typical @ 5 VDC plus interface loads
Input Ripple 2% peak to peak @ 5 VDC
Output Circuits OL7272 high voltage line driver:
VOL = 0.5 V max @ 20 mA sink
VOH = Vcc-0.8 V @ 20 mA source
RS-422 compatible @ 20 mA source
Open Collector Output Sink up to 100 mA
Incremental Output Format Quadrature outputs with index pulse
See waveform reference chart in spec sheet for timing and gating options
Accuracy ±1.0 arc minute
Max Operating Frequency 500 kHz
Symmetry 180° electrical ± 10% typical
Minimum Edge Separation 67° electrical at 100 kHz
Code Incremental
Rise Time Less than 1 µs
Electrical Protection Reverse protected to 0.6 A cont., 4 A for 1µs
OL7272 outputs over voltage and short circuit protected

Environmental Specifications

Storage Temperature -40 to 125°C
Operating Temperature -20 to 100°C typical
Humidity 98% non-condensing
Vibration 20 g's @ 50 to 500 CPS
Shock 50 g's @ 11 ms duration
IP Rating IP66 solid shaft, IP64 blind bore

Mechanical Specifications

Maximum Shaft Speed 8000 RPM
Blind Bore Diameter (Tolerance) 0.375", 0.500", 0.625" (+0.0006/-0.0000")
Solid Shaft Diameter (Tolerance) 0.250", 0.375", 10 mm (+0.0000"/-0.0004")
Allowable Shaft Runout 0.001" TIR
Bearings Precision ABEC double shielded
Shaft Material 303 stainless Steel
Bearing Life 1.5 X 10⁹ at rated load
Moment of Inertia 3.4 X 10⁻⁴ oz·in·s²
Acceleration 1 X 10⁵ radians/s²
Starting Torque 1.0 in·oz max
Radial Shaft Loading 40 lb for rated bearing life, 80 lb max
Axial Shaft Loading 40 lb for rated bearing life, 80 lb max
Housing Anodized aluminum
Weight 13 oz typical
Termination Radial Exit: 10, 7 & 6 pin MS, wire gland w/ 24" Cable
Axial Exit: 10, 7 & 6 pin MS, wire gland w/ 24" Cable
Mounting Flange w/ 1.181" female pilot
Flange w/ 1.250" male pilot
Servo w/ 1.181" female pilot
Servo w/ 1.250" male pilot
Size 25 flange and pilot
Size 25 servo and pilot
2.250" bolt circle flex mount
Info & Pricing

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Consult factory for configurations not shown (e.g. resolution, commutation, etc.).

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