A potentiometer is a simple knob that provides a variable resistance, which we can read into the Arduino board as an analog value. In this example, that value controls the rate at which an LED blinks. 

 In this circuit, you’ll be using a photoresistor, which changes resistance based on how much light the sensor receives. The Photoresistor will output a high voltage when it is getting a lot of light and a low voltage when little or no light is present. 

Servos are ideal for embedded electronics applications because they can move to a position accurately. By varying the pulse of voltage a servo receives, we were able to move a servo to a specific position. In this circuit, I used PWM (pulse width modulation) to control and rotate a servo. 

For this circuit I am using a small DC motor. In order for the motor to function properly we needed to incorporate a transistor, which can switch larger amounts of current that the Arduino can. Once the circuit is up and running in Arduino I used the serial port provided in the Arduino IDE to control the output of motor. 

In this circuit I am using a shift register to create an integrated circuit. The shift register gives the Arduino an additional eight outputs at the expense of using only three digital inputs. The circuit itself performs a function similar to that of the dancing LED’s (circuit 4). When the circuit is running the eight LED’s on the bread board will light up starting with the first one and moving all the way up to the eighth one. Each LED turns on and then off in succession with the one on either side of it.