Line follower sensor - TCRT500 module, analog and digital output

Linefollowers are small, yet simple and popular robots. They are built to follow line drawn on ground. Line usually is black, placed on white background. Most common sensor used to build line follower robot is reflective sensor. This sensor is used to detect how dark ground is. Placing few sensors in line will create line edge detection module. Robot drives to keep edge in the middle of sensor array, thus will follow the line.

This small module (PCB have just 31 x 14 mm) has TCRT5000 optical sensor and support circuit on it. It has two outputs - digital (1/0 depending on if sensor is over the line or not) and analog output. Analog output has voltage proportional to degree of darkness of ground. You may it use that output in less standard designs.

While analog output provides most information then digital is easier to use. This module has one feature very usefull if You want to use digital output - sensitivity regulation with potentiometer. Depending on material used to create line (printed on paper, built with black tape or other) You may need different level when sensor changes it’s output. You can adjust each sensor individually to current lighting and used material for line.

TCRT5000 works in infrared range (wavelength 950 nm) but (from few tests we performed) is affected slightly with changes in lighting. Sensitivity regulation will help with that too.

LED showing digital output state is very handy when You need to check if sensor works correctly in given lighting conditions.

Specification:

• Sensor: TCRT5000
• Power supply (Vcc): 3.3V-5.5V
• Output voltage range - 0V - Vcc
• Size
  • PCB: 31 x 14 mm (w/o goldpins)
  • Sensors head over PCB: 11 mm
  • Total height (from sensor head to potentiometer): 17 mm
• Mount hole 1x3 mm
• Two green LEDs - one for power second for digital output state