My design for a parabolic microphone
Here is how I constructed my present parabolic microphone from sched40 PVC pipes , Edmund Scientific Parabolic dish (3080254) and Radio Shack microphone element( 270-092).
I have used the microphone with both my cassette recorder and my video camera.
The pipe I used is a white PVC pipe often used for cold water applications such as underground sprinkler systems. I used the 3/4" size because it happened to fit the 3/4" hole in the center of the parabolic dish.
The red rubber washers were cut from sheet gasket material that was obtained from a plumbing supply shop. Their purpose is to insulate the dish from sound traveling through the pipe from the users hands.
The 10/24 threaded rods are glued with epoxy into slots cut into the 3/4" PVC Adapter. The rubber bands that stretch between the rods hold the microphone element and insulate it from sounds passing through the mounting. This system allows you to adjust the position of the microphone so that it is at the focal point of the parabolic dish, which for me was 4 1/2".
Since the parabolic reflector has a mirror surface you should paint it with a dull color to prevent startling either the birds or your neighbors.
Here is an mpg(307kb) of a 3D perspective of the microphone.
Here is a simplified drawing of the setup together with the part number for the microphone itself together with a schematic diagram for the electrical circuit involved.
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