var max=250; 

function count(f) {
	var txt=f.metin.value;
	var nb=txt.length;
	if (nb>max) { 
		alert("Maximum "+max+" Karakter Girisi Yapabilirsiniz !");
		f.metin.value=txt.substring(0,max);
		nb=max;
	}
	f.nbcar.value=nb;
	document.forms["mebcoll"].nbcar_rest.value = 250-document.forms["mebcoll"].nbcar.value;
}

function timer() {
	count(document.forms["mebcoll"]);
	setTimeout("timer()",100);
}