Does that mean that hair dryers do not need pure sine wave output? Can anybody explain to me what needs pure sine wave. I have heard tell that rechargeable toothbrushes won't. What else? How about rechargeable shavers? Or a laptop with usual external power supply?
Hairdryers are fine on modified sine wave. Rechargeable toothbrushes and shavers that use inductive chargers (ie those that have no apparent electrical connection and just sit in or on a plastic cradle of some description) need pure sine wave. You might find that an inductive charger will work for a short while on modified sine but sooner or later it will ruin it. For those of us softies who like an electric blanket, the electronic controllers on modern blankets also need pure sine wave.
I don't know about laptops as I only charge mine direct off the 12v but someone else on here is bound to know.