[sdiy] Percussion MIDI controller

[Magnus Danielson]

From: Ingo Debus <debus at cityweb.de>
Subject: Re: [sdiy] Percussion MIDI controller
Date: Fri, 25 Feb 2005 09:37:51 +0100
Message-ID: <88ECBBC6-8708-11D9-99A8-000A9571C136 at cityweb.de>

> 
> Am Donnerstag, 24.02.05 um 17:52 Uhr schrieb Magnus Danielson:
> 
> > I've done exactly this exercise and we had no problem what so ever. We 
> > used a
> > standard Tektronix desktop scope in single-trigger position. We had a 
> > 450 us
> > time difference between the two cases. Converting this time difference 
> > into
> > CV and Gate should be trivial, infact I intend to do the exercise very 
> > soon
> > anyway. We used two piezo-elements and a standard electric PVC tube.
> 
> PVC tube! That's a great idea. Anybody know the speed of sound in PVC?

Let me see... the circa 1 meter tube we had created about 220-240 us delay
from one end to the other.

> How do I attach the piezo disks to the tube? I don't think piezos like 
> to be bent. Is it better to attach them at the sides of the tube, or 
> flat on some sort of "end cork"? In the former case I think I'd need 
> some "adaptor" (perhaps made from aluminum) concave on one side, 
> matching the tube's diameter, and flat on the other.

To quote my friend who made the one we tried: "You thermo-glue them on in the
obvious way!". Basically you thermo-glue them on each end. I haven't done the
exercise myself yeat, but it didn't take him that long and the cost of material
was really nothing to fuzz about.

The piezo-elements he used where cheap ones in plastic casing. I'll see if I
can't find them myself and make a few attempts myself.

Cheers,
Magnus