var top_update_time = 60;
var bottom_update_time = 60;
var sidebar_update_time = 60;

function set_timers(elm, uTime){
    if(!uTime) return;
    if(!elm) return;
    
    uTime+= Math.floor(Math.random()*11);
    uTime = uTime * 1000;
    
    setInterval(function() { 
        elm.src = elm.src;    
    }, uTime);
}

var tBegun = document.getElementById('begun_top');
var bBegun = document.getElementById('begun_bottom');
var sBegun = document.getElementById('begun_sidebar');

set_timers(tBegun, top_update_time);
set_timers(bBegun, bottom_update_time);
set_timers(sBegun, sidebar_update_time);