var efecto_ap_velocidad=40;
//var efecto_ap_color = 0;
//var efecto_ap_suma = 10;
var efecto_ap_color = -10;
var efecto_ap_suma = 10;
function aparecer(){
//alert(efecto_ap_color);alert(efecto_ap_suma);
var obj = document.getElementById('formulario_aj');
obj.style.display = "block";
efecto_ap_color += efecto_ap_suma;
if (!(efecto_ap_color>=110)){
obj.style.filter = 'alpha(opacity='+efecto_ap_color+')';
			 obj.style.opacity = efecto_ap_color /100;
			 obj.style.MozOpacity = efecto_ap_color /100;
			 obj.style.KHTMLOpacity = efecto_ap_color /100;
		window.setTimeout ("aparecer();", efecto_ap_velocidad);
}
}
function desvanecer() {
var obj2 = document.getElementById('formulario_aj');
		efecto_ap_color -= efecto_ap_suma;
	if (!(efecto_ap_color <=-10)){
	obj2.style.filter = 'alpha(opacity='+efecto_ap_color+')';
			 obj2.style.opacity = efecto_ap_color /100;
			 obj2.style.MozOpacity = efecto_ap_color /100;
			 obj2.style.KHTMLOpacity = efecto_ap_color /100;
		window.setTimeout ("desvanecer();", efecto_ap_velocidad);
	}
	else 
		obj2.style.display = "none";
	//window.setTimeout ("obj2.style.display = 'none'", 1000);
	}
	
function llama(){
if (efecto_ap_color<=0){
  aparecer();
}
else {
  desvanecer();
}
}