I found this cool site:
http://www.wa4dsy.net/filter/hp_lp_filter.html
Where you can design you own low or high pass filtre.
Enter your parameters and it computes the parts you need, quite neat I thou=
ght.
Phil
----- Original Message ----
From: David Martin <>
To:
Sent: Wednesday, 15 August, 2007 2:28:45 AM
Subject: [Nature Recordists] Lightning arrestor and high-pass filter
Thanks to everyone who commented on my question from a couple of
weeks ago about lightning arrestors to protect my roof mic . After
digging around, it seems clear there is no foolproof
arrangement. The consensus is that the mic should be protected by a
well grounded conductor (e.g lightning rod) and should
be disconnected when not in use. So, that's my plan. I placed my
mic near my solar hot water panels. I'm hoping for the best.
I've had it working for three nights now. I'm getting decent
signals, but I'd like to use as much gain as possible. However, low
frequency noise from traffic, trains, and and aircraft can overload
the system. (I'm a mile from relatively busy railroad tracks and 10
miles from a busy airport). I am just monitoring songbird flight
calls and only need to record above 2000 Hz, so I should be able to
greatly reduce the problem with a high-pass filter. Can anyone
suggest a filter that might work or does anyone know of a plan for
building one?
David
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