PWM Fan Speed Controller v1.1

Added A/C signal/supply wire (untested)
Arduino sketch (without A/c):
int potPin = A0;
int motorPin = 9;
int potValue = 0;
int motorValue = 255;
void setup() {
// Serial.begin(9600);
analogWrite (motorPin, motorValue);
delay(5000);
}
void loop() {
potValue = analogRead(potPin);
motorValue = map(potValue, 0, 1023, 20, 255);
analogWrite(motorPin, motorValue);
// Serial.print("pot = " );
// Serial.print(potValue);
// Serial.print(" motor = ");
// Serial.println(motorValue);
// delay(2);
}