WYSI, I'll second Gypsy's advice to get an Intellitouch. They're completely chromatic and even though they won't attach to anything on an Autoharp — at least I haven't found any way to put them on mine — they work well by just laying them down on the harp. They list for about $79 US, but many places sell them for about $52 to $57.

If, as somebody mentioned, it doesn't work well in the lower registers, just touch the string you're tuning in the middle and tune with harmonics.

cheers,

david