Trim with QTR-3RC reflective sensors - digital - Pololu 2457*

Compact bar with three reflective sensors with the size of 32 x 8 mm. It has analog outputs, it is powered with the voltage of 5 V.

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Price 19,90 zł


  • Number of sensors: 3
  • Supply voltage: 5 V
  • Current consumption: 50 mA
  • Outputs: digital - frequency signal
  • The optimum distance for measurement: 3 mm
  • The maximum distance for measurement: 6 mm
  • Dimensions 32 x 8 x 3 mm
  • Weight: 0.6 g
The kit includes one module with sensors and two goldpin straps: straight and corner for self-soldering.


Strap is used in robots like line follower, as sensors, detecting the track as a black line on a white background. The module consists of three reflective sensors that contain the IR transmitting LED and receiver in the form of phototransistor. The output are the digital signals which can be read using any microcontroller with an A/C converter, including Arduino.


Between the sensors left is 9.5 mm space so that a strap was reliable on the tracks applied with the standard insulating tape with the width of 19 mm.



Strap QTR-3RC, similarly to the QTR-8RC module, has digital outputs. Reading the measurement data, is carried out by charging the capacitor (the indication of high status), and measuring the time of discharge of it through phototransistor. This option has the following advantages:

  • It does not require an analog-to-digital converter
  • Gives the possibility of parallel read of the values of three sensors

A typical sequence of the reading of sensor's values:

  1. Setting the I/O pins of the microcontroller as outputs and the creation of the high status
  2. Waiting a few micro seconds - charging the capacitor of 2.2 NF
  3. The setting of the I/O pins as input (high impedance status)
  4. Measuring the discharge time of the capacitor by waiting till the I/O lines come to low status
With a high intensity of the reflected signal, the measured time will be oscilating within a few microseconds. A small amount of reflected light will be discharging the capacitor for a few milliseconds. The exact time depends on characteristics of the pins of the microcontroller.

The product is compatible with Arduino

For users of AVR microcontrollers and modules of Arduino, the manufacturer has prepared special libraries facilitating the convenient operation of sensors: the AVR library, the Arduino library.



Each of phototransistors uses a capacitor and an auxiliary circuit that can read data from the sensors by measuring the time of discharge.


Current to each transmitting LED was set to 17 mA, what at powering with the voltage of 5 V makes that the average current consumption of the whole module is about 50 mA.



Diagram of the module QTR-3RC.



Posting the payment for the order on our account on a business day up to 13:00 means sending the goods on the same day!


The time of payment depends on the hours of ELIXIR session of the sender's bank and the recipient of the transfer (more information on this subject, for example on the website


The table presents available forms of delivery in Poland


Carrier and

Bank wire

by cash


Poczta Polska

terms of service

9,90 PLN17,90 PLN1-3 days

Kurier GLS

terms of service

14,90 PLN22,90 PLN

1-2 days

Paczkomaty 24/7 

terms of service

12,90 PLN-1-3 days

If the amount to pay for products exceeds 500 PLN
Delivery is for free!


  • Free delivery of orders over 500 PLN does not apply to parcels addressed outside of Poland.
  • Free delivery does not apply when changing orders.
  • The delivery period is counted in working days from the date of dispatch of the order.