How about a microphone to actually detect the sound level?  You could use=
=20
simple bandpass filters to prevent picking up stray signals from the othe=
r=20
drums.

Cheers,
-Neil.



On Wednesday 31 March 2004 08:14 am, Joe Jansen/TECH/HQ/KEMET/US scribble=
d:
> Thx Ken.  Correct me if I am wrong, but it sounds like it only detects
> on/off, rather than impact strength.  I wasn't aware that the piezo's p=
ut
> out that high of a voltage.  hmmmmm.........
>
> It does give me some evidence that the piezo will do the job, however. =
 I
> still want to try out the accelerometers, also.
>
> Good stuff!
>
> --Joe Jansen
>
> pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU> wrote on
>
> 03/30/2004 10:20:36 PM:
> > Joe Jansen wrote:
> > > Thanks for any suggestions!!!!!
> >
> > Hi Joe,
> >
> > I still have my E-mu Systems Drumulator drum machine (I love the '80s=
!).
>
> I
>
> > never bought the pad programmer for it, but here is some information
>
> that
>
> > might be useful to you regarding their piezo interface:
> >
> >
> >
> > From E-mu Systems Drumulator Pad Programmer manual:
> > ---------------------------------------------------
> >
> > {
> > Pad Programmer - Theory of Operation - Revision of 2/27/84
> > The Pad Programmer consists of four independent trigger sensors with
> > appropriate
> > circuitry, with a common housing and power supply.
> > The power supply is a simple three terminal regulator +5V supply. The
>
> input
>
> > voltage is
> > between 8 and 25 VDC and the current requirements are small enough
>
> (around
>
> > 40 mA
> > when an LED is firing, less quiescently) that heat sinking is not
>
> required.
>
> > The plug in
> > wall unit supplies nominally 10V DC, which is filtered and regulated.
> > The sensor is a piezo-electric crystal mounted in a housing designed =
to
> > transmit
> > pressure from a vertical strike by a drumstick, and attenuate vibrati=
ons
> > conducted by the
> > housing. This assembly is glued together and tested at the factory.
>
> Service
>
> > on these
> > assemblies will generally be by replacement, as repairs are difficult=
 to
> > accomplish and
> > will frequently be unreliable.
> > The sensor produces a substantial voltage spike (10 to 100+ volts),
>
> which is
>
> > loaded by a
> > parallel capacitor and resistor, and rectified by a full wave bridge.
>
> The
>
> > resulting positive
> > voltage is attenuated and applied to one terminal of a comparator. Th=
e
>
> other
>
> > terminal of
> > the comparator is adjusted for the desired sensitivity threshold. The
>
> trim
>
> > range is set to
> > stay within the common mode range of the comparator. Positive feedbac=
k
> > around the
> > comparator is provided to minimize marginal switching. The comparator
>
> output
>
> > triggers
> > a one-shot which will both swallow any comparator oscillation or
>
> multiple
>
> > triggering, and
> > provide sufficient pulse width for the LED amplifier and for the outp=
ut
> > trigger pulse. Both
> > of these signals are buffered from the one-shot output.
> > For information on adjusting the sensitivity trims, refer to the earl=
ier
> > section.
> > }
> >
> >
> > Best regards,
> >
> > Ken Pergola
> >
> > --
> > http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body

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