var how_many_ads = 7;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
url="faleconosco.shtml";
alt="";
banner="ran/v01.gif";
width="138";
height="140";
}

if (ad==2) {
url="c_inter2.shtml";
alt="";
banner="ran/v05.gif";
width="138";
height="140";
}
if (ad==3) {
url="c_dina_inter.shtml";
alt="";
banner="ran/v09.gif";
width="138";
height="140";
}
if (ad==4) {
url="c_infancia.shtml";
alt="";
banner="ran/v13.gif";
width="138";
height="140";
}
if (ad==5) {
url="c_eletiva.shtml";
alt="";
banner="ran/v17.gif";
width="138";
height="140";
}
if (ad==6) {
url="c_historia.shtml";
alt="";
banner="ran/v21.gif";
width="138";
height="140";
}
if (ad==7) {
url="c_astrocartografia.shtml";
alt="";
banner="ran/v25.gif";
width="138";
height="140";
}