Counting the 5V blinks

Hi, I want to calculate the number of 5v output from the device. actually it was 12 volt coming from the device i used 7805 and give it to arduino. Now i want to calculate the number of times its output reaches HIGH.as it is reaching to high and LOW very fast and sometimes slow too. There have been issue with fast blinks as it miss some blinks. and with slow blinks as the output reaches HIGH and it remained high the count should not keep calculating(it should be counted as single HIGH count) but it keeps calculating. and want toshow it on LCD. Not very good with coding.here is my code

int Blink = 8;
int count = 0;


void setup() {

  Serial.begin(9600);

  pinMode(Blink, INPUT);
}

void loop() {
  // read the input pin:
  int BlinkState = digitalRead(Blink);
  // print out the state of the button:
  //Serial.println(BlinkState);
  if (BlinkState == 1)
{
  BlinkState =0;
  count++;
  Serial.println("COUNT = ");
  Serial.println(count);
}
  delay(10);        // delay in between reads for stability
}

Urgent help required Thanks

Have a look at the ButtonStateChange example.

Thanks JimboZ i will try this and let you know the results

i used 7805 and give it to arduino.

Noooooooooooo!

Do not do this.
Just use two resistors in a potential divider.

That is a power regulator chip and is not designed to do what you want. That is probably why it misses fast blinks, it is designed to hold up the voltage as much as possible.