

QTR-1RC Reflectance Sensor (2-Pack)
The QTR-1RC reflectance sensor carries a single infrared LED and phototransistor pair in an inexpensive, tiny 0.5" x 0.3" module that can be mounted almost anywhere and is great for edge detection and line following. The output is designed to be measured by a digital I/O line. This sensor is sold in packs of two units.
Note: The QTR-1RC reflectance sensor requires a digital I/O line to take readings. The similar QTR-1A reflectance sensor is available with an analog output.
![]() |
The Pololu QTR-1RC reflectance sensor carries a single infrared LED and phototransistor pair. The phototransistor uses a capacitor discharge circuit that allows a digital I/O line on a microcontroller to take an analog reading of reflected IR by measuring the discharge time of the capacitor. Shorter capacitor discharge time is an indication of greater reflection.
The LED current-limiting resistor is set to deliver approximately 17 mA to the LED when VIN is 5 V. The current requirement can be met by some microcontroller I/O lines, allowing the sensor to be powered up and down through an I/O line to conserve power.
This sensor was designed to be used with the board parallel to the surface being sensed. Because of its small size, multiple units can easily be arranged to fit various applications such as line sensing and proximity/edge detection.
For a line sensor with eight of these units arranged in a row, please see the QTR-8RC reflectance sensor array; for a similar array of three slightly different sensor components, see the QTR-3RC. For a similar, smaller sensor with longer range, and intended for use with the board perpendicular to the surface, please see the QTR-L-1RC reflectance sensor.
![]() |
QTR sensor size comparison. Clockwise from top left: QTR-3RC, QTR-1RC, QTR-L-1RC, QTR-8RC. |
---|
![]() |
QTR-1RC output (yellow) when 1/8" above a black line and microcontroller timing of that output (blue). |
---|
Like the Parallax QTI, the QTR-1RC module has sensor outputs that require a digital I/O line capable of first charging the output capacitor (by driving the line high) and then measuring the time for the capacitor to discharge through the phototransistor. This measurement approach has several advantages, especially when multiple units are used:
The typical sequence for reading a sensor is:
![]() |
These steps can typically be executed in parallel on multiple I/O lines.
With a strong reflectance, the discharge time can be as low as several dozen microseconds; with no reflectance, the discharge time can be up to a few milliseconds. The exact time of the discharge depends on your microcontroller’s I/O line characteristics. Meaningful results can be available within 1 ms in typical cases (i.e. when not trying to measure subtle differences in low-reflectance scenarios), allowing up to 1 kHz sampling.
Our Pololu AVR library provides functions that make it easy to use these sensors with our Orangutan robot controllers; please see the QTR Reflectance Sensors section of our library command reference for more information. We also have a Arduino library for these sensors.
This module has a single mounting hole intended for a #2 screw (not included); if this mounting hole is not needed, this portion of the PCB can be ground off to make the unit even smaller. Each pack of two reflectance sensors includes sets of straight male header strips and right-angle male header strips, which allow you to mount them in the orientation of your choice (note: the header pins might ship as 1×6 strips that you can break into two 1×3 pieces). You can also solder wires, such as ribbon cable, directly to the pads for the most compact installation.
|
|
![]() |
QTR-1A Reflectance Sensor (2-Pack) |
![]() |
Sharp GP2Y0A21YK0F Analog Distance Sensor 10-80cm |
![]() |
QTR-8RC Reflectance Sensor Array |
Data sheet
Manufacturer BTC Korporacja sp. z o. o. Lwowska 5 05-120 Legionowo Poland sprzedaz@kamami.pl 22 767 36 20
Responsible person BTC Korporacja sp. z o. o. Lwowska 5 05-120 Legionowo Poland sprzedaz@kamami.pl 22 767 36 20
Module with 15 QTR type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 50 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4215
Module with 13 QTRX type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4353
Module with 5 balancing sensors for Balboa 32U4 balancing robot. Pololu 3577
Module with 15 QTRX type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 50 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4315
Module with 1 QTRX type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 30 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4401
Module with 2 QTR type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 30 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4102
Module with 15 QTRX type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 50 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4415
No product available!
No product available!
Infrared sensor module with TCRT5000. Can be used to detect objects in close proximity or detect lines in "Line Follower" robots
Module with 6 QTR type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4246
Module with 5 QTR type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4105
Module with 1 optocoupler type QTRXL with RC (digital) output. It is supplied with the voltage from 2.9 to 5.5 V, detects objects at a distance of up to 80 mm. Pololu 4501
Module with 5 QTR type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4245
Module with 7 QTRX type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4307
Module with 3 QTRX type optocoupler with analog output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 30 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4403
Module with 6 QTRX type optocoupler with RC (digital) output. The module operates from 2.9 V to 5.5 V, detects objects at a distance of up to 40 mm. The sensor will be used in projects that require detection of changes in the ground, e.g. in linefollower robots. Pololu 4306
QTR-1RC Reflectance Sensor (2-Pack)