Shy Little Car

Summary: 

A small toy car that moves. The car is attached by embroidery floss to a DC motor that will reel the car in when the string is pulled taut by the motion of the motor. Motion is turned on and off by input to a photocell: the motor is activated when the photocell registers lower light values or is covered by a hand. The photocell can be kept separate from the car for use as a controller, or taped to the back of the car to make a "shy car" that moves away from the hand that is reaching for it.

Materials:

Embroidery Floss

1 Toy Car

Tape

1 photocell

1 solderless breadboard

1 Tip120 transistor

1 diode

1k ohm resistor

220k ohm resistor

1 Battery Case (2 AA Batteries)

1 DC Motor

Jumperwires

1 Arduino Uno

Code: 

/*

Photocell input is used to turn the motor on and off. 

If a hand is placed over the photocell, the car will move forward.

 */

int photocellPin = 0;   // select the input pin for the potentiometer

int motorPin = 9; // select the pin for the Motor

int val = 0;      // variable to store the value coming from the sensor

void setup() {

  Serial.begin(9600);

}

void loop() {

  val = analogRead(photocellPin);    // read the value from the sensor, between 0 - 1024

  Serial.println(val);

  if (val <= 0){ //photocell is covered

  analogWrite(motorPin, 100); 

  }

  else{

     analogWrite(motorPin, 0);

  }

}