Re: piezo mics and midi dancers

["Jon Wagner" <jondrums@hotmail.com>]

> Using the MidiSolutions box, I can use a potentiometer
> to send midi cc commands.  Is it possible, (holding
> my breath) to have a piezo electric transducer
> vary a resistance, which drives the midi box...
>
> I'm sure somehow it could be done, so the question
> is really is it inexpensive, and easy enough that
> someone would actually send a circuit diagram?


Piezo discs will have a voltage across their terminals which corresponds to
the CHANGE in force on it.  In other words if I put 10 pounds of force on a
piezo disc, the voltage with spike up when I first put the force on, and
then settle back down while the force is constant, then spike negative when
I remove the force.  So sending CC messages isn't at all what you would 
want
to do with a piezo disc.  Piezo discs would be good for sending note-on
messages (they are used in most electronic drum triggers).  Just wire up 
the
two terminals of the piezo disc to a 1/4" jack and plug it into any drum
brain that accepts trigger inputs and you'll have a velocity sensitive midi
note-on trigger.  There are lots of writeups on the web about how to make
your own electronic drum trigger pads - search on "piezo drum trigger."
Jon