Powershell counter

$tick = 3  # === Tick every three second
$bef = Get-Date -Format HHmmss

while ($true)
{
    $now = Get-Date -Format HHmmss
    if ( [int]($now - $bef) -eq $tick)
    {
        $now # === just show time, but you can do here more useful stuff :-)
        $bef = $now
    }
}