Two photos:
http://frog_recordist.home.mindspring.com/naturerecordists/QuickParabolic1.jpg
http://frog_recordist.home.mindspring.com/naturerecordists/QuickParabolic2.jpg
I did this in about a hour, this is what the drawing I gave below looks
like. I did not mount the mic inside the end cap, and it's all just
slipped together (you would want to glue the handle to the T, but
probably not the rest). This one is made with 3/4" PVC pipe. The
reflector is my spare Telinga one, the same design would work with
others like the one available from Edmond Scientific:
http://www.scientificsonline.com/Products/DisplayProduct.cfm?productid=2135
Note the Edmond one is polished for solar cooking, it would have to be
painted to keep from cooking your mic.
Walt
Walter Knapp wrote:
> deer2me22002 wrote:
> > Can i use a uni-
>
>>directioal mike in a parabola? Can i build my own parabolic? How can
>>it be done?
>
>
> Yes a unidirectional mic will work in a parabolic. The biggest problem
> with them is that usually the mic picks up from the end, so you have to
> aim it at the dish, which means it sticks way out there. Such a dish is
> unbalanced to the front and tiresome to aim. The small tie tac mics make
> about the best inexpensive mic for a parabolic.
>
> The hardest part of building a parabolic mic is coming up with a
> suitable parabolic reflector. You need one at least 20-24" in diameter,
> but not too big or heavy to carry, plastic ones are a bit better than
> aluminum as they ring less if hit.
>
> You can buy a Telinga dish as a spare part from Doug if you can't find
> anything else. The Telinga dish has the added advantage that it can be
> rolled up, though not tightly.
>
> As far as the rest of it, here's a drawing of one way, I picked this off
> the net and modified it so it would be a bit more durable:
> http://frog_recordist.home.mindspring.com/naturerecordists/pipes-2.gif
>
> I went by home depot yesterday and picked up the fittings so I could
> build a example. There I found some rug castors that are plastic disks
> with rug on one side, Ideal for clamping the dish where I show rubber or
> foam. I'll put up a page on this as soon as I have time to get it made.
> I've got a spare dish for my Telinga and a Sony ECM-T140 mic I can use.
> I got parts so I could make it out of 1/2" or 3/4" pipe, I'm sure the
> mic support will be ok in 1/2", not sure on the handle. Be sure and find
> the focus of the reflector before cutting the pipe to length. You
> probably want to plug the threaded fitting with foam as well to keep
> sounds from coming in up the pipe.
>
> There are lots of variations, a parabolic mic is really fairly simple.
>
> If you bought the Telinga dish and the sony tie tac mic new, you should
> still be able to put it together for about $150 US. Most of that is in
> the dish and mic. So finding those cheaper can save lots.
>
> I've heard of folks making small parabolic dishes by heating a sheet of
> thermoplastic held by it's edges until it sags to shape. Doing that with
> a circle big enough to do a 2' reflector would be a bit of a
> undertaking. It has to be heated evenly.
>
> Walt
>
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