The apparatus, shown in the picture below, automatically rotates the photovoltaic cell (PV) to track the sun.
The PV cell is placed on this padding in the picture below, which is a close-up of the upper right corner in the photo above. This is also where the photo-resistor sensors are located. At the bottom of this platform, there are two photoresistors that look like two small circles separated by a wooden wall. The purpose of this wall is to ensure that the PV cell is facing directly at the sun. If it is not, then it casts a shadow on one of the sensors. As I explained in a previous blog post, the sensors have different resistance values depending on how much light they are exposed to. This idea is the basis for the C++ code. If one resistor value is smaller than the other, than the Arduino outputs to the motor to turn one direction. If the other resistor value is smaller, than the Arduino outputs to the motor to turn in the opposite direction. This process will continue to take place until both sensors are receiving the same amount of light and no shadows are cast on them.
The last main piece to the apparatus is the servo motor. The motor is connected to the bottom of the black wheel shown below. On either side of the wheel is a track that allows the wheel to move left and right. This allows the wheel to be pushed up against the lazy susan (which is barely shown on the right hand side of the picture). As the motor turns, the black wheel turns and when it is pushed up against the lazy susan, that turns as well. This is what rotates the PV cell in the phi direction.
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