var position = 1;

//vars
var delay = 4000;
var speed = 600;

//initiate
function start(_delay, _speed) {
	
	if (_delay !== undefined) { delay =  _delay;}
	if (_speed !== undefined) { speed =  _speed;} 

	setTimeout(_fadeOut, delay);
	$('a#banner_1').css('display', 'block');
}

function _fadeOut() {
	$('a#banner_' + position).fadeOut(speed, function() {
		
		if (position < 4) {
			position++;
		} else {
			position= 1;
		}
		
		_fadeIn()
	});
}

function _fadeIn() {
	$('a#banner_' + position).fadeIn(speed, function() {
		setTimeout(_fadeOut, delay);
	});
}