On May 15, 2019, at 5:28 PM, Marcus D. Leech <address@hidden> wrote:
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 Wed, May 15, 2019, 1:20 PM John Coppens <address@hidden wrote:
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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