[sdiy] About that spherical impulse generator...

[Glen]

At 11:10 PM 1/9/04 , harrybissell wrote:

>You have to consider the vibtatory modes of the discs... they are usually 
>mounted at a nodal point and flex like a drumhead. Bind them at the edges 
>and you might be right back to the beaming problem

I would have thought that the disc movement was more piston-like and less
like a flexing drumhead, since the piezo crystal is expanding across the
whole surface of the disc, and not expanding from the primarily the center,
like a drumhead.

So, what is the best way to mount a disc for this purpose? Should I put a
drop of epoxy in the center, and mount it over a solid, flat surface?
Should I use a sheet of glue across the complete rear side of the disc, and
mount that on a solid, flat surface? Should I suspend the disc over a hole,
nearly as big as the disc itself, and glue the outer edge of the disc, as
if mounting a speaker by its rim?

I suspect that mounting it like a speaker might produce the most volume,
but mounting it with a sheet of glue to a hard, dense, flat surface would
possibly provide the best transient response.


>Have you just considered explosives ???   ;^P

That's actually been tried, but the frequency response of a typical
explosion isn't flat enough. It's just too boomy.   ;)

later,
Glen Berry