QTR-8A 8-Channel Reflectance Sensor Array Module 


The QTR-8A reflectance sensor array is intended as a line sensor, but it can be used as a general-purpose proximity or reflectance sensor. The array module is a convenient carrier for eight IR emitter and receiver (phototransistor) pairs evenly spaced at intervals of 0.375″ (9.525mm). Each phototransistor is connected to a pull-up resistor to form a voltage divider that produces an analog voltage output between 0V and VIN (which is typically 5V) as a function of the reflected IR. The lower output voltage is an indication of greater reflection


  • No analog-to-digital converter (ADC) is required
  • Improved sensitivity over voltage-divider analog output
  • Parallel reading of multiple sensors is possible with most microcontrollers
  • Parallel reading allows optimized use of LED power to enable the option
  • Operating voltage: 3.3-5.0 V
  • Supply current: 100 mA
  • Output format: 8 digital I/O-compatible signals that can be read as a timed high pulse
  • Optimal sensing distance: 0.125″ (3 mm)
  • Maximum recommended sensing distance: 0.375″ (9.5 mm)



Dimensions2.95″ x 0.5″ x 0.125″ (without header pins installed)
Operating voltage3.3-5.0V
Supply current100mA
Output format8 digital I/O-compatible signals that can be read as a timed high pulse
Optimal sensing distance0.125″ (3mm)
Maximum recommended sensing distance0.375″ (9.5mm)
Weight without header pins0.11oz (3.09g)


  • Line following robots: Detects lines or tracks for navigation and path following.
  • Obstacle detection: Identifies obstacles or objects in front of the sensor array.
  • Edge detection: Detects the edges of objects or surfaces for positioning or proximity sensing.
  • Surface quality inspection: Measures reflectance to assess the quality or condition of surfaces.
  • Material identification: Differentiates between materials based on their reflectance properties.


Download the Datasheet of QTR-8A reflectance sensor from the link given below.