function timeStart()
{
    var t=setTimeout("updateTime()",1000);
}

function setTime(hours,minutes,seconds,div,diff,calc)
{
    if(calc == 'min')
    {
        hours = hours - diff;
    }
    else
    {
        hours = (hours + diff);
    }

    if(hours > 24)
        hours = hours - 24;

    if(hours < 10)
        hours = '0'+hours;
    if(minutes < 10)
        minutes = '0'+minutes;
    if(seconds < 10)
        seconds = '0'+seconds;

    document.getElementById(div).innerHTML = hours + ':' + minutes + ':' + seconds;
}

function updateTime()
{
    var currentTime = new Date();
    var hours = currentTime.getHours();
    var minutes = currentTime.getMinutes();
    var seconds = currentTime.getSeconds();

    setTime(hours,minutes,seconds,'tijd1', 0, 'min');
    setTime(hours,minutes,seconds,'tijd2', 5, 'min');
    setTime(hours,minutes,seconds,'tijd3', 12, 'plus');

    timeStart();
}