Spin Motor Spin (CIRC-03)

Purpose

The purpose of this circuit experiment is to integrate the usage of transistors and motors.

Equipment

• 1 x Transistor P2N2222AG
• 1 x Diode
• 1 x 10k Ohm Resistor
• 1 x Toy Motor
• 7 x Wires
• 1 x Arduino Uno
• 1 x Breadboard
• 1 x Breadboard Sheet

Program Details

     With the new pieces, combination of small and big ones, it is a bit of a hassle connecting them as they overlap, but it isn't hard. Again, just as the resistors are specific to the direction in which they are connected, the diode, transistor and motor is as well. This was our first problem, both our diode and transistor was wired wrong. After rewiring and programming, it worked. See the image below.

Assembled and functional motor.

     Assembly takes around 5-10 minutes. The coding corresponds directly to what happens in the circuit. The main loop consists of three segments: turning the motor on and off, setting the motor to a specific speed while on, then bringing the speed down to a specific level and turning it off, and finally, accelerating and decelerating the motor. The programming within these categories are basic, using variables such as 'delaytime' and 'onspeed' for the different numerical values in the program. To turn the motor on and off, use HIGH and LOW. For the acceleration and deceleration, the speed limits are stated then the program counts up or down, using the same format as that used for repeating a code. Note that in the 'void loop()' two segments are commented out. This means they don't run.

Results

     As mentioned earlier after rewiring certain components, and uploading the provided code, the motor worked perfectly. First we didn't realized that the motor was programmed to function in three different ways, we only noticed that it'd pause or stop working sometimes. However after analyzing the code, we understood perfectly. If you hold your finger to the motor, as shown below, you can feel the motor work.

Hold your finger to the motor to feel it work.

     Tips

     To make sure you understand whats going on with the motor, analyze the program before uploading it. This time with the assembly, attach the smaller parts, in the right direction, then attach the wires overhead. This will make it easier and faster to work on the small breadboard. Also, right after attaching a part, check to make sure it is attached in the correct direction instead of checking amidst all the other parts. 


Next Steps & Associated Program Modifications


     There are small modifications that can be made to the already existing program to make it do more than it does. This is because two segments of code with different functions are already commented out. By getting rid of the slashes, the 'void loop()' will run those segments as well. One can also change the numerical values of the variables. See the program sequence with two segments now. The code in orange is essentially not needed for this program (not copied and pasted).



int motorPin=9;


void setup()
{
  pinMode(motorPin, OUTPUT);
}


void loop() //the program runs the following segment repeatedly no matter what
{
  motorOnThenoff(); //this turns the motor on for a certain time, then off
  motorOnThenoffwithSpeed(); //turns the motor on with a particular speed, then off
  //motorAcceleration(); this segment will not run for the program
}


void motorOnThenoff()
{
  int onTime=2500; //how long the motor will be on for
  int offTime=1000; //how long the motor will be off for
  digitalwrite (motorPin, HIGH); //turns the motor on
  delay(onTime); //function above is active for the duration of 2500ms
  digitalwrite(motorPin, LOW); //turns the motof off
  delay(offtime); //function above is active for the duration of 1000ms
}


void motorOnThenoffwithSpeed()
{
  int onSpeed=2000; //what speed the motor will be when it is on
  int onTime=2500;//how long it will stay on
  int offSpeed=50;//what speed signals that the motor is off
  int offTime=1000;//how long it will be off
  analogWrite (motorPin, onSpeed);//turns the motor on to the set speed
  delay(ontime);//keeps the motor on for 2500ms
  analogWrite(motorPin,offSpeed);//turns the motor off
  delay(offtime);//keeps the motor off for 1000ms
}


void motorAcceleration();
{
  int delaytime=50;
  for (int i=0; i<256; i++);
  {
    analogWrite(motorPin,i);
    delay(delaytime);
  }
  for (int i=255; i>=0; i--);
  {
    analogWrite(motorPin, i);
    delay (delayTime);
  }
}  



Reference


The Sparkfun Inventor's Guide