IIRC you can also build a shotgun mike with a single tube with correctly spaced perforated holes in it. Can't find the reference now.
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That would be lots easier. And cheaper.
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Here is a PDF of the entire June 1964 issue of Popular Electronics, featuring that DIY shotgun microphone. Lots of cool transistor projects! I just might try that fish caller.
Edit, I now see the link was already given above.
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very cool! I had seen this on wikipedia Acoustic mirror - Wikipedia the video is fantastic! 27 miles is enough distance to get the weapons ready!
Yes! But no help with buzz bombs!
This document is simply fantastic! I don't have the knowledge to fully understand, but I managed to understand very well about the frequency ranges related to the tube size, genius! I never imagined something like this!
thank you for the explanation!
Sorry, I didn't explain correctly! It would be a ready-made reflector with a microphone, as I would have to adapt some things, I preferred to make one.
I would like to add a link with a short and simple video to help discover the central point of the dish, I used a laser, metallic tape found in stationery stores, I made a simple template on the 3D printer to place the laser in the square, I used a ruler , paper and pen to write down the center point.
Just stick the tape on the parabolic and reflect the laser in the direction to know the center point.
I have also attached a document that helps with the parabolic central point formula.
Maybe it will help other people!
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Also, stack end to end for extra low frequency sound capture!
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My friend this was really good! I am going to do! Taking advantage here, do I place an electret microphone right at the bottom of the centralized pot? Do you have any suggestions?
I'm going to test with 01 pot and another with two pots to increase the size, following the friend's tip below.
I won't be able to make it this weekend, but I'm going to buy it to finish it off with the potatoes 
Sounds good to me! Let us know how well it works.
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I'll document the basics of testing and post it here! I got it. tks
Something else to think about if you want is if your "dish" is spherical rather than parabolic in shape, you can "point" it by moving the microphone around rather than the dish. That's how certain telescopes with a fixed elevation "see" so much of the sky.
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At the bottom will probably work, but the frequencies that enter will reflect and have a focus (center point) similar to the paraboloid. This "focus" is a similar concept to making wind chimes (hollow tubes hanging from strings). The "hang" location is at a (math - 1/4 length of tube???) distance from the end to be on an anode (wave crossing point). Experiment with inserting your microphone (sound sensor) at different distances inside the tubes. Looking forward to hearing the results.
friend, I'll set the stage and come back here soon with test results! thanks for the class!
interesting, I'm studying about the dish to be able to print! thanks for the class!
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