Trim with QTR-3A reflective sensors - analog - Pololu 2456*

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

Listwa z czujnikami odbiciowymiSpecification:

  • Number of sensors: 3
  • Supply voltage: 5 V
  • Current consumption: 50 mA
  • Outputs: analogue  signal (0 - 5 V)
  • 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 is an analog voltage which can be read using any microcontroller with an A/C converter, including Arduino.

Czujniki line follower  

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.



There are several solutions that allows to read data from the sensors QTR-3A

  • Connecting the outputs to microcontroller with analog to digital converter, for example, of the analog Arduino pins
  • Connecting to the digital inputs via analog comparator, to determine the threshold between white and black
  • Connecting directly to the digital pins, using built-in microcontroller internal comparator

The product is compatible with Arduino

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


The optimal distance from the surface to the sensors is 3 mm, the maximum, at which the sensor functions, is 6 mm. To picture the situation, we present the oscilograms, showing the detection of black lines on a white background at different distances from the surface.


The analog signal after the detection of black lines on white surgace at a distance of 3 mm on the left, and 9 mm on the right side.



Each of phototransistors has pulling-up external resistor, allowing direct connection of the outputs to the microcontroller and the read of the voltage from the range 0 - 5 V that is appropriate for the color and distance from surface.


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-3A.



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.