I am currently using an universal adapter. The adapter has output range from 12-20V. My laptop uses 19V. The adapter comes with various sized tips that can be used. Initially i was using a yellow tip. That got messed up a bit. Now i was wondering if i can use the black tip the provided since it fits in the power input of my laptop? Is it safe to do this? The tip specifies 18V-18.5V-19V. Size 11.