| Dollar
Store Parabolic Microphone |
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| This project started with a paint roller handle and one of those silly folding plastic umbrella hats shown above. Both came from a local store where everything is a dollar. I just added a short length of 9/32" brass tubing and a Radio Shack 33-3028 Stereo Clip-On Microphone. The whole process took about an hour and cost less than $20.00. Radio Shack has discontinued (and discounted) this great little microphone. It now costs about $16.00 if you can find it. Theoretically, one could make this parabolic mic with only dollar store items. I recently noticed they were selling a "hands-free" extension for a cell phone. One could cannibalize the mic from that and use it instead of the Radio Shack mic. The sound would probably be unsatisfactory but as a $3.00 exercise for kids, it cannot be beat. The dollar stores also carry headphones for . . . you guessed it, $1.00. Even the glove holding the paint roller handle came from the same store. If you find this interesting and decide to try one of these you can find more detailed and updated instructions at the Instructables website. It is also featured in Make Magazine, Volume 14. Make has published a video version of the project too. If you decide to make one, I would love to hear about your experiences. Email me. Jim Lee |
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The
Finished Microphone
It looks pretty good,
weighs practically nothing, and disassembles
easily. This paint roller handle is actually adjustable. Just a twist
of the
handle and it extends up to 19 inches. The umbrella itself opens to
about 19
inches in diameter. It is necessary to remove the headband and punch a
hole in the very top for the handle. Otherwise, no modificatons to the
umbrella
are needed. As for the handle, remove the
plastic roller holders, file off the little burrs that hold them
on, and you are in business.
I used the beam from
a laser level pointed at the umbrella from a
distance to determine the approximate focal point of the parabola (such
as it is). A flashlight would probably work just as well. Because the
umbrella is not a perfect parabola, the focal point is a little fuzzy.
Nevertheless it works.
So what
does it sound like?
I made a
recording
using two identical microphones, one mounted in the
parabolic rig and one held next to it. The parabolic mic was sent to
the left channel of my MD recorder. The other mic was sent to the right
channel. I pointed both in the direction of an obliging squirrel
perched in a tree about thirty yards away. There was also a murder of
crows located about sixty yards away in the same direction. At some
point a cardinal
decides to make a cameo appearance. As you can
tell, I live in an urban area with lots of urban sounds. Here are the
results converted to 128kbps-44.1kHz mp3s. Compare the strong sound of
the squirrel on recording (2) with the much
weaker sound of the same squirrel on recording (3). Listen to (4) for a
side by side comparison.
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