arduino code for this: http://aaron-sherwood.com/blog/?p=1007

coil_wrapper_counter.ino

int sensorPin = A0;
int buttonPin = 2;
int ledPin = 12;
int sensorValue = 0;
int buttonValue = 0;
int count = 0;
int target_wraps = 10;
bool check = true;

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);  
}

void loop() {
  sensorValue = analogRead(sensorPin);
  buttonValue = digitalRead(buttonPin);
  
  if (sensorValue > 900 && check == true) {
     count++;
     check=false;
  } 
  if (sensorValue < 900) {
    check=true; 
  }
  if (buttonValue==1){
    digitalWrite(ledPin, LOW);
    count=0;
  }
  if (count>target_wraps-1) {
    digitalWrite(ledPin, HIGH);
  }
  Serial.println(sensorValue);                   
}