$(document).ready(function(){
	var img_str = "/media/images/{n}.jpg";	
    var seconds = 10;
    var range = 8;
    var el = $('#switch');
	
	timer();
	
	function timer()
	{
	    setTimeout(
	        function(){
	            switchImage(el);
	        },
	    seconds*1000);
	}
	
    function switchImage(el)
    {
        var random = Math.floor(Math.random()*(range+1));
        var src = img_str.replace('{n}', random);

        el.attr('src', src);
        
        timer();
    } 
});