Pololu QTR-8A Reflectance Sensor Array

Overview:

The QTR-8A reflectance sensor array is a highly efficient module designed for line-following robots and general-purpose proximity or reflectance sensing. It features 8 IR LED/phototransistor pairs mounted on a 0.375″ pitch. The LEDs are arranged in pairs to reduce current consumption, and a built-in MOSFET allows for the LEDs to be switched off, providing power-saving options. Each sensor outputs a separate analog voltage, which can be easily interfaced with microcontrollers for various applications.

Key Features:

• Analog Voltage Output: Each sensor produces an analog voltage between 0 V and VIN, corresponding to the amount of reflected IR, making it easy to measure reflectance.
• Power Efficiency: LEDs can be turned off using the onboard MOSFET to conserve power, with current-limiting resistors adjustable for 3.3V and 5V operation.
• Flexible Interfacing: The sensor outputs can be read directly by a microcontroller’s ADC, or through a comparator to generate digital signals.
• Breakable Design: The module can be split into two smaller, independent sensor arrays if space is limited or fewer sensors are needed.

Specifications:

• Dimensions: 2.95″ x 0.5″ x 0.125″ (without header pins)
• Operating Voltage: 3.3-5.0 V
• Supply Current: 100 mA
• Output Format: 8 analog voltages
• Output Voltage Range: 0 V to supplied voltage
• Optimal Sensing Distance: 0.125″ (3 mm)
• Maximum Sensing Distance: 0.25″ (6 mm)
• Weight: 0.11 oz (3.09 g)

Interfacing Options:

• Microcontroller ADC: Directly measure the analog voltage outputs.
• Comparator: Convert analog voltages into digital signals for microcontroller I/O.
• Digital I/O with Comparator: Use the microcontroller’s internal comparator for simple digital signal interfacing.

Applications:

• Line-following robots
• Reflectance sensing
• Proximity detection in robotics and automation

Additional Information:

• Compatible with Pololu AVR library and Arduino library for seamless integration.
• Ships with a 25-pin 0.1″ header strip and a 100 Ohm through-hole resistor.

Included Components:

• 25-pin 0.1″ header strip
• 100 Ohm through-hole resistor

The QTR-8A reflectance sensor array provides a flexible and efficient solution for a variety of sensing needs, making it an excellent choice for robotics enthusiasts and developers.