On 05/15/2019 03:23 PM, Brad Hein
wrote:
Great suggestion thank you! This also gives me new
topics to read up on as I am still a VLF amateur.
[Sent from
mobile device]
I used a Berhringer "mini-MIC" microphone amplifier, which has a
balanced, XLR, input, and has bandwidth out to
about 90kHz. Worked a champ. Not as cheap as a DIY
op-amp+transformer approach, but more convenient,
to be sure.
On Thu, 2
May 2019 16:22:24 -0400
Brad Hein <address@hidden> wrote:
> I took a Raspberry Pi and attached a 48KHz USB sound
card, with a big
> magnetic loop antenna fed into the mic.
Just a suggestion: If you have a loop antenna, which is a
symmetrical antenna,
and couple it to an asymmetrical input (MIC), you will make
the antenna
more sensitive to static noise. I'd suggest you use either a
transformer or
an 'instrumentation amplifier' with an operational amplifier
to convert
the signal from the antenna to asymmetrical signal.
A transformer would be easiest to install at the base of the
antenna (no
need for a supply). The op-amp amplifier would cover a larger
bandwidth.
(it would also offer some protection for your computer).
John
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