mounting homebrew contact mike

[CCartCat at aol.com]

Mounting with some kind of putty/goo/adhesive walled about the edge of the 
piezo case, you can mount it face down on a surface so the wadcutter is 
making contact.  In my own extremely unrigorous (esp. for Synth DIY) 
experiments, face down is somewhat louder.  Only very lo-fi quality 
comparisons were made, but the face down tone is brighter, perhaps more 
tinny. If you just barely make contact, you'll get a buzzy noise as would be 
imagined.  But it's not that difficult to make solid contact and avoid the 
buzziness.  YMMV.

[Details, details:  'Course, as dawn breaks on Marblehead, I realize that the 
wadcutter was chosen to be glued flat end against the plate.  Since I thought 
the point of contact was that flat end, the hollow base of the pellet is what 
I glued to the plate.]

Thanks for the V-drum tip.  More fun with styrofoam.

And, FWIW, for the 1.49 piezo with the deeper case, I'm gluing a tiny 
mounting nut to the base of the wadcutter to shim the difference. 

:-)
Kevin

In a message dated 9/12/99 9:06:34 PM, you wrote:

<<You have "boldly gone where no man has gone before" I think...

I don't care if the wadcutter protrudes or not... I am just adding weight in 
the
center...
so that when the outside edge moves through space (outer case)... inertia 
makes
the pellet want to stand still... and bends the piezo in the process. So when 
I
mount this thing the pellet is up (away from the mounting surface).  Are you
indeed making the pellet touch the vibrating surface ???   Tell me MORE !!!

If you want the pellet or (whatever) to touch the mounting surface use any
material....
The Evil Empire (R0land) uses a styrofoam cone for their V-Drums...

SOT: It would be easy to clone the "Vdrum" The secret is in their "double knit
nylon" drum head... Its like a screen that has stiffness like a drum head, but
passes air like a screen door... so no sound. There is a styrofoam cone that
touches the head and relays the force to a poezo mounted deep in the shell...
Clever and a two-year-old could copy it.....

:^) Harry

CCartCat at aol.com wrote:

> The $1.49 piezo has a deeper plastic case (I got both just in case or
> whatever).  So the wadcutter doesn't *just* protrude from the face of that
> piezo (as it does when glued into the other piezo).  It's too short to
> protrude at all.
>
> I tried gluing one wadcutter on top of the other.  Kinda tall--protrudes 
more
> (too much?).  Haven't glued the doubled wadcutter to the $1.49 piezo yet, so
> this is all guesswork and no experience ;-) , but you might try the doubled
> wadcutter.  Use the putty/blue goo/beeswax/adhesive to both hold the piezo 
to
> the object mic'd and to shim the difference.  Or glue something solid and
> appropriately sized onto the wadcutter to extend it about an 1/8" beyond the
> piezo case surface.  (After all, wadcutters come in a box of 250.  So you 
can
> experiment with them--or take up shooting.)
>
> And if you spring for the $1.79 piezo, you'll can build that and then 
compare
> & contrast the $1.49 options to the original design.  Or do an exchange for
> the $1.79 and remove all doubt. (I've opened the blister pack on mine, am
> curious, have approx. 240 wadcutter pellets on hand--thus, I'm committed.)
>
> Hope this OT blather helps,
> Kevin
>
> In a message dated 9/10/99 11:58:36 PM, Harry B. wrote:
>
> <<Hell... give it a try...
>
> Essentially they are similar. The two wire unit is all you require... The
> three
> wire unit has a little "feedback" strip that is used with a single 
transistor
> to
> make an oscillator (the main element (speaker) vibrates and the little 
element
> picks it up (mic) and the transistor amplifies it... and because the piezo 
has
> mass and stiffness (and is mounted at the nodes) it has a natural resonant
> frequency and oscillates there...
>
> I've used both kinds...
>
> search for MuRata Erie (or someting like that) they manufacture all these
> devices...
>
> And it doesn't have to be a wadcurrer pellet, any small weight would do
> something... experiment... BB, lead shot... solder ball... whatever.
>
> "Hell its only money"   :^) Harry
>
> P.S. I got the 273-064 (just went downstairs and looked....)
>
> PPS. The pellets are Beeman H&N Match wadcutter pellets cat # 3011
> (but for heavens' sake use whatever you can find....)
>
> Christian Oncken wrote:
>
> > Well, I went to radioshack today... I forgot to take the part# with me, so
> > after much headscratching and deliberation, I came home with a different
> > model than the one described in your email.... its part# 273-073a, 'piezo
> > transducer' $1.49.  it says 1500 to 3000hz...
> >
> > I think I did see the 273-064 part... it was $1.79 just like you said... 
but
> > it was labeled 'piezo buzzer' or something like that, I dont know if 
there's
> > a difference...
> >
> > Still havent got the wadcutter pellet yet...
> >
> > But anyway, since I got the wrong part, can you tell me if this one will
> > work?  Or would you suggest taking it back for an exchange on the right 
one?
> >
> > Any suggestions, ideas or advice you can give me would be greatly
> > appreciated.  I'm new to this stuff... Any web resources for this kind of
> > thing?
> >
> > thanks for all your help.
> >
> > Christian Oncken.
> >
> > >Yes... airrifle pellet... very light (as pellets go) and has a flat nose 
so
> > it
> > >is easy to glue reliably...
> > >
> > >The piezo as a driver will probably not have enough "balls" to drive a
> > spring,
> > >esp at low frequencies... I'd use a iron spring (or iron rod... pipe etc)
> > ir for
> > >a small spring, a ferrite bead... and drive with an electromagnet driven
> > from a
> > >stereo amp... Get enough turns so you don't fry it...
> > >
> > >Slinkies make good springs... if you put a magnetic pickup on a few
> > stretched
> > >slinkies, and then KICK it it makes a wonderful explosion...  "Yes" (the
> > band)
> > >shared that idea during a soundcheck during the "Relayer" tour... used in
> > "The
> > >Gates of Delirium"... Its like kicking a spring reverb but much BIGGER 
!!!
> > >
> > >Christian Oncken wrote:
> > >
> >>
>>