I suspect many 110/120V 60Hz laptop power supplies (eg American) would cope with 115V at 400Hz. The first thing most electronic power supplies do is rectify it to DC anyway. Then they chop it up again to make AC in the 20KHz+ range. That way they can use smaller ferrite parts. Try it at your own risk. I've no idea how noisy it is or what the tollerance is. Wouldn't want a few spikes to take out your hard drive.