What is does:
It searches for the brightest light source like the sun.
Step 1: How it works
How it works:
I’d made a sensor of 4 LDRs with sheets between them
The withe stips are the LDRs

the four LDRs get the same amount of light on them.
Example1 when the light is left on top:
right-top, right-down, left-down are in the shadow
and left-top get the most light
Example2 when the light is on top
left and right down are in the shadow and top is in the light
Step 2: Parts List
- 2 x servo’s
- 4 x lightdepending resistors (ldr)
- 4 x resistors 10K
- 1 x Arduino
- 2 x potentiometers 10k (value doesn’t matter)
Step 3: The set-up
Just hot glue it together!!!
Step 4: The circuitry
Step 5: The Code
you can download the code down this page
#include <Servo.h> // include Servo library
Servo horizontal; // horizontal servo
int servoh = 90; // stand horizontal servo
Servo vertical; // vertical servo
int servov = 90; // stand vertical servo
// LDR pin connections
// name = analogpin;
int ldrlt = 0; //LDR top left
int ldrrt = 1; //LDR top rigt
int ldrld = 2; //LDR down left
int ldrrd = 3; //ldr down rigt
void setup()
{
Serial.begin(9600);
// servo connections
// name.attacht(pin);
horizontal.attach(9);
vertical.attach(10);
}
void loop()
{
int lt = analogRead(ldrlt); // top left
int rt = analogRead(ldrrt); // top right
int ld = analogRead(ldrld); // down left
int rd = analogRead(ldrrd); // down rigt
int dtime = analogRead(4)/20; // read potentiometers
int tol = analogRead(5)/4;
int avt = (lt + rt) / 2; // average value top
int avd = (ld + rd) / 2; // average value down
int avl = (lt + ld) / 2; // average value left
int avr = (rt + rd) / 2; // average value right
int dvert = avt – avd; // check the diffirence of up and down
int dhoriz = avl – avr;// check the diffirence og left and rig
if (-1*tol > dvert || dvert > tol) // check if the diffirence is in the tolerance else change vertical angle
{
if (avt > avd)
{
servov = ++servov;
if (servov > 180)
{
servov = 180;
}
}
else if (avt < avd)
{
servov= –servov;
if (servov < 0)
{
servov = 0;
}
}
vertical.write(servov);
}
Read more: Arduino Solar Tracker