Lawnboy wrote:Harry, as you mentioned this I remember a short piece I came across in an old newsletter. If you have the archive CD, check out Vol 32 No 4 pg 10 for a simple scanner made from speakers by Ed Norwill. It looks interesting, especially if paired with a similarly scanned camera, but its also probably quite noisy and obnoxious while in operation.
Oh looking its the one with the 4 speakers...i had tried speakers a few years ago but not 4 like that, only 1 speaker not to bad on the 12.5 hz and as you say there is a noise problem not so good on 400hz for any mechanical movement .
I swapped to HD voice coils results were much better i recall .
Reading hes experiment again i see the sine wave gave him disappointing results this might be a big problem then for any tuning fork which can only do sine waves.
I wonder on the loud speaker side of things if cutting away parts of the speaker perhaps leaving 3 or 4 Membranes that should cut down the sound and keep the vibrating movement might work.
I did look a little into using the laser movement on dvd drives and vibrating stepper motors might be worth a review .
This fella has done some nice work with what we are talking about
http://spt06.chez-alice.fr/00/scan1.htm
http://spt06.chez-alice.fr/00/scan2.htm
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.