Originally Posted by
cwatters
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.
Would just like to confirm that the switched-mode power supplies on almost all laptops operate exactly as CW says. Frequency (50/60/400 hz) is not an issue - however switching off from engine/APU/ground power can generate the unwanted spikes mentioned here.
Older iron transformer coupled power supplies would not like 400hz - these are sometimes still used for cell chargers and some handheld computing devices. Compared to 50/60hz power levels, the internal voltages can increase 10-30 percent at 400hz - some devices will tolerate this increase better than others. If the adaptor seems heavy for it's size, it probably has an iron core transformer - use at your own risk !