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Microphone design and building instruction updates
March 12, 2002
The left figure in the BUILDING THE CIRCUIT section had the C1 and C2 capacitors labeled incorrectly - they were reversed. This error has now been corrected.
September 21, 2002
Information on the Knowles microphone element has been added - it may now be ordered online directly from Old Bird.
August 16, 2005
Regarding the size of the dinner plate used in the "flowerpot" microphone construction, we are now recommending using the ~8-inch diameter "Rubbermaid" type dinner plate rather than the larger 10-inch version. The audio signal gain is the same for both plates if you are targeting species whose flight calls are 3 kHz or greater (thrushes & warblers/sparrows). The benefit is that the plastic wrap holds up better on the smaller diameter plate. During heavy rain events, the plastic wrap is pushed down by heavy rain and it can be punctured by the microphone element. This can lead to water seeping in and damaging the mic element.
April 28, 2015
Major update in instructions