Catwalker

So I received a question some time ago (sorry to whomever posted it):

What pin do I hook up a motor to?

The short answer: you don't, not directly.

A direct current, or DC, motor is the most common type of motor. DC motors 

normally have just two leads, one positive and one negative. If you connect these

two leads directly to a battery, the motor will rotate. If you switch the leads, the

motor will rotate in the opposite direction.

The Arduino can only provide 40mA at 5V on its digital pins. Most motors require

 more current and/or voltage to operate. A transistor can act as a digital switch,

enabling the Arduino to control loads with higher electrical requirements. The 

transistor in this example completes the motor's circuit to ground. Arduinos are

great to direct drive an led or two, but a DC motor will draw too much current, and

will probably fry the Arduino. Here is the circuit to drive the motor:

(In this case, the transistor I'm using is a P2N2222AG, not much different

from a standard 2N2222 - it's what I had within reach when I made the video.)

Now, if you watch the

video,  you will see that

this circuit differs from

the one I show in the video,

in that there is an extra 330

Ohm resistor in parallel to

the 10 K Ohm resistor, this

is because the 10 K resistor

was too high a value, the

voltage to turn on the transistor

was dropped too much, and the transistor would not turn on. With the

330 Ohm and 10K ohm in parallel, the circuit works just fine.

Here is the breadboard layout created in Fritzing:

Here is the video:

Here is the Sketch:

int motorPin = 9; // DC motor is  connected to this pin

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

void loop() {
  motorOnThenOff();
}

/*******************************************************/
/* MotorOnTheOff turns the motor on, then off          */
/* Code is more-or-less the same as turning an LED     */
/* on and off                                          */
/*******************************************************/

void motorOnThenOff(){
  int onTime = 1000;    // How long does it run?
  int offTime = 2000;   // Turn it off
  digitalWrite(motorPin, HIGH);   // This command turns the motor on
  delay(onTime);                  // run for this many milliseconds
  digitalWrite(motorPin, LOW);    // We're done? Turn motor off
  delay(offTime);                 // Wait for offtime to complete
}

Have fun!

じゃまた