Saturday, December 28, 2013

Electronic Circuit Schematic Line Sensor using Light Dependent Resistor (LDR)

Robometricschool. - One main part when we want to make or building Line Follower Robot (LFR) is LINE SENSOR. Beside we can design line sensor using infra red LED, we also can design line sensor using light sensor that called Light Dependent Resistor (LDR). 

In this time we will give you simple electronic circuit schematic that named line sensor using LDR that can used as the line sensor for line follower robotic. And you can try to build and test this schematic easily.

Circuit Schematic

Figure 1. Line Sensor using Light Dependent Resistor (LDR) (Drawing by Circuitstoday)

Component List
  1. R1, R2 : 220 ohm
  2. R3, R6 : 2K2 ohm
  3. D1, D2 : LED
  4. R4, R7 : LDR
  5. R5, R8 : 2K2 ohm


Electronic circuit schematic of Line Sensor using LDR like in figure 1 above show as that we will use left and right line detection. 
  1. The light came from LED D1 and LED D2 after get current and voltage follow from R1 and R2.
  2. The light from LED will influence the resistance of LDR R4 and R7, It is will make change the voltage in point A and B.
  3. We know that the changing voltage because it is the voltage divider that connected LDR with R3, R6 and also R5, R8. 
  4. The value of the voltage changing came from the strong and weak the LED lighting that reflected from the line. 


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