 // pin for mosfet
 const int mosfetA = 16; //A1
 const int mosfetB = 17; //A2
+
+//SD_PULSE regulates the duration of the shaking pulse 
+const int MIN_SD_PULSE = 5; //in seconds
 const int MAX_SD_PULSE = 20; //in seconds
+
+//SD_PAUSE regulates the pause between pulses
+const int MIN_SD_PAUSE = 1; //in minutes
 const int MAX_SD_PAUSE = 7; //in minutes
 
 

  {
    SD_vibrate = true;
    SD_A = now();
    SD_AB = random (5, MAX_SD_PULSE);
    next_action = now() + SD_AB;

    lcd.setCursor(13,0);

  {
    SD_vibrate = false;
    SD_B = now();
    SD_BC = random (MIN_SD_PAUSE, MAX_SD_PAUSE ) * 60; 
    next_action = now() + SD_BC;

    lcd.setCursor(13,0);
