[sdiy] oscillating plate

[cris at music-service.nl]

Hi,
yesterday the plate was oscillating 'like water'.......
i use 2 speakers and a amp, one speaker as exiter and one as 
reciver, i fixed the speakers at the two ends of the plate and i switch 
on the amp, after twoo seconds you can hear an very low drone and 
the plate vibrates. i pute some salt on the plate on that way i was 
able to see the waveforms in the plate, soon i will make some foto's.
after the steel plate i tried with a glas plate and it works too, hier 
frequency this time, this plate was smaller, but the effect was grate, 
more flexibel, this plate was oscillating in more than one direcrion, 
the salt gives more complex forms...
thanks guys for help....
cris