/*

pin assignments:

10   - base of npn transistor #1 2n2222 (either one)

11  - base of npn transistor #2 2n2222 (the other one…)

*/

int t1 = 10;

int t2 = 11;

int speedValue;

void setup(){

pinMode(t1, OUTPUT);

pinMode(t2, OUTPUT);

off();

delay(5000);

}

void loop(){

forward();

delay(3000);

reverse();

delay(3000);

off();

delay(3000);

}

void forward() {

digitalWrite(t1, LOW);

  // ramp in from min to max in increments of 5 points:

  for(int speedValue = 0 ; speedValue <= 255; speedValue +=5) { 

    // sets the value (range from 0 to 255):

    analogWrite(t2, speedValue);         

    // wait for 30 milliseconds to see the effect    

    delay(30);                            

  } 

  // ramp out from max to min in increments of 5 points:

  for(int speedValue = 255 ; speedValue >= 0; speedValue -=5) { 

    // sets the value (range from 0 to 255):

    analogWrite(t2, speedValue);         

    // wait for 30 milliseconds to see the effect    

    delay(30);                            

  } 

}

void reverse(){

digitalWrite(t2, LOW);

  // ramp in from min to max in increments of 5 points:

  for(int speedValue = 0 ; speedValue <= 255; speedValue +=5) { 

    // sets the value (range from 0 to 255):

    analogWrite(t1, speedValue);         

    // wait for 30 milliseconds to see the effect    

    delay(30);                            

  } 

  // ramp out from max to min in increments of 5 points:

  for(int speedValue = 255 ; speedValue >= 0; speedValue -=5) { 

    // sets the value (range from 0 to 255):

    analogWrite(t1, speedValue);         

    // wait for 30 milliseconds to see the effect    

    delay(30);                            

  } 

}

void off() {

analogWrite(t1, 0);

digitalWrite(t2, HIGH);

}