QTR-1A Reflectance Sensor power supply issues

I’m a 3rd year mechanical engineering student and I’m just recently getting introduced to robotics. I’m trying to use the QTR-1A Reflectance Sensors with an arduino uno r3 to pick up a white line in a red surface. I have been able to make the sensors identify the difference between red and white, but to do so, I need to supply at least 7 volts to the sensors. There will be 5 of the sensors in parallel. The problem we are running into is that when we attached this a power supply unit, it worked fine. When we tried to implement 9-volt batteries, it drained the batteries so quickly. Do we just need more batteries or better batteries? Any help will be appreciated.


You have an interesting approach to this problem. However, I do see a couple of additional issues with your setup other than your battery draining quickly:

  1. The 9V battery is a very poor power source for this kind of application. You might consider using a AA battery pack instead. (For more information on why, you can read this blog.)

  2. This sensor has an intended operating voltage of 5V; by increasing the voltage to over 5V, you risk burning out the IR LEDs.

  3. The output of this sensor can be as high as your supply voltage, by using a supply over 5V, you risk damaging your Arduino’s I/O pins.

You might have already considered these things; I just wanted to be sure you were aware of these additional risks.