Linked is the diagram as built.
http://home.comcast.net/~richpeet/ccdiag.jpg
Other notes if you used this diagram.
1. This is a two lead Condenser microphone element. Modification
would be needed for three wire.
2. This design is a PZM design in order to give an effect of a higher
quality mic element. This means that the mic diaphram each on a
different side of the plexiglass needs to be mounted as close to
flush with the surface as possible. Then the reflected sound
pressure wave is summed to the direct pressure wave giving the effect
of a mic element with half the noise value. The size of the
plexiglass determines the pitch of the sound that can be reflected. a
surface can only reflect the pitch equal or longer than the size of a
1/2 wavelength in space. 8"x11" should be considered a minimum size.=20
I like the rectangular shape so that the gain drop off is not an
abrupt shelf.
3. If you want to put capacitors in the signal path because you don't
know if your preamp has them I recommend 2 - 4 uf tantilum or metal
film caps.
4. A .01 uf ceramic could be placed across the power supply
electrolytic to give additional rf interfierence protection. I just
didn't nor did I see a problem when tested near radio towers.
5. A nut the size for a mic stand could be epoxied to the bottom of
the plexiglass to supply a mic stand mount. Just have not gotten
around to it.
6. To mount components within the plexiglass simply use a drill and
then fill in the remaining hole with clear epoxy.
7. I did not have a small etching tool to cut a channel for the wires
to the capsules and then flood with epoxy and that is why there
currently is the piece of electrical tape. This should be corrected.
I hope someone finds value in this as it really does perform beyond
what the cost is. This prototype is now with a new recordist trying
it out near his deer hunting stand at a rut site for the next few
weeks.
Rich Peet
--- In "Greg Winterflood"
<> wrote:
> --- In "Rich Peet"
<>
> wrote:
> > I have not posted a cost saving design lately so I thought I
would.
> > I still sandbagged a few more for some other time. I have not
> > stopped building.
> >
> > But here is a great project under $15.00 if you can find the
> > plexiglass. Most of the electronics were mounted and epoxied
> within
> > the sheet to make the whole assembly field worthy under any
> > conditions. Windscreen not shown but is based on a small foam
> ball
> > cut in half.
> >
> > This new design is as simple as I could make it.
> > Photos taken before epoxy seal of all parts and electronics.
>=20
>
> Rich
>
> That looks and sounds great. Any chance of a 'mud map' circuit
> diagram?
>
> We have stores here called "Tandy" which are some kind of
RadioShack
> off-shoot; but can't guarantee equivalency of product parts.
>
> Can you tell me how to aim the finished product? Side on, or face
> on??
>
> Cheers
>
> Greg
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