Hi all,

This may be of interest. It's an article dealing with
the electronics of infrasound detection using simple
(cheap) electret condenser microphones.

Worth a read:

   http://earth.unh.edu/johnson/MICROPHONES/ISLA14.pdf
   http://earth.unh.edu/johnson/MICROPHONES/J4.pdf

While on holidays I plan to construct this device. It
will be my third sensor dealing with infrasound. You
never know, one might pick up the infrasonic signature
of an earthquake, big volcanic eruption ,fireball or
an elephant ! A previous sensor certainly picked up
fireballs (Meteors).

The electret microphones were purchased on "ebay" as
a 100 microphones for $99.00  The sellers apparently
has 70,000 of these, so I'm sure a new ebay item will
appear soon. Anyhow the ebay search line is:

Panasonic Electret Condenser Microphone WM-034DM

   The Sellars web address:
   Hi-Tech Enterprises, Inc. http://www.videoequipment.com

(Note they are a discontinued line but if you have
  100 of them, they never will be !)

You can download the data on these WM-034 microphones
 from the "Panasonic" site at:

http://www.panasonic.com/industrial/components/audio/aud_mic.htm

Google Search Strings:

  J4 Microphones Popo
  Microphones infrasonic
  Microphones infrasound
  Prototype for an Expendable Infrasound


Cheers Arie
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