remove this post

 var myLight : GameObject;
 var t : float;
 var threshold : float = 0.5f;
 
 function Update() {
      t += Time.deltaTime;
      if(t >= threshold) {
           t = 0.0f;
           if(myLight.enabled == true) {
                myLight.GetComponent(Light).enabled = false;
           }
           else {
                myLight.GetComponent(Light).enabled = true;
           }
      }
 }

You can also change the light.intensity instead.

There are also parameters to do it automatically with particle systems