Charley Wenzel made it very safe: here is
http://www.techlib.com/electronics/lightning.html,
I used cross-correlation to identify the "right electrical noise"
Alex
On 6/25/2014 8:22 PM, Brian Lloyd wrote:
On Wed, Jun 25, 2014 at 4:42 PM, paul swed <paulsw...@gmail.com> wrote:
I am currently using a 12AX7 as a ELF preamp and have for years.
A note in the coldest part of winter preheat the tube low filament voltage.
They tend to fracture.
It sits 200 ft from the house as far away in the woods as possible.
That said and back to the thread. At these frequencies tubes do work. The
12AX7 can be found on vlf.it and numbers of tubes will work. They run 12 V
on the plate. They also stand up to nearby lightning very well.
So Diddier now you have no excuse. I can't wait to implement your design on
one of my stm boards. Not sure how to get this back on time-nuts topics
Regards
Try a 6DJ8 instead of the 12AX7. It has a higher GM and a LOT more
bandwidth. What kind of risetime are we talking about for a lightning
strike? And why not a loop antenna? That should provide plenty of signal
but not destructive voltages.
I know you are talking about measuring lightning strikes but if you get the
impedance high enough, you can actually measure the earth's electric field.
(It is about 200V/m if I recall properly.) Interestingly it is affected by
the solar flux and solar wind.
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