Somebody else please verify this.
If you look at the power supply for the laptop, I think you will find that it can handle a really wide range of input.
Mine's not in front of me, but I think it is 100-250v 50-60Hz input. It converts that to something like 18v dc but I don't remember exactly.
Point being, I'd be surprized it the power supply for the laptop couldn't smooth out square wave input.
Again, please get a second opinion before you fry anything.
Have Fun,
-Dan M