Hi,
this is just something I am playing with as an experiment of an idea I had... I'm trying to use a simple air coil to detect an extremely weakly magnetized sphere moving. The signal amplitude is so tiny that even with an oscilloscope you can barely see that something is happening in the noise floor but cannot really distinguish the signal itself, what kind of off-the-shelf amplifier would you use?
Jfet or instrumentation amplifier dev kit? Or some other solution?
If a JFET or INA, which in-amp would you suggest (that perhaps is designed for reading coils)?
Thank you
As you already stated, the signal is barely visible in the noise.
Therefore, an amplifier will not do the job at all, because it amplifies the noise in the same manner.
I suggest to 1st set up your pick-up coil in a bridge configuration, and 2nd to use a Phase-Locked method to detect the movement of your magnet.
Maybe it's possible to move the magnet in a repetitive manner, then you could synchronize to the frequency of your moving system.
I made magnetic AC measurements on superconductors, as well on very small samples (100µm x 300µm), using a so called Hartshorn bridge.
The differential bridge output AC signal was in the mV, down to the nV range.
So I used 100x differential low noise amplifiers first, to achieve an SNR of up to 108dB @ mV input signal level, for digitization with my 3458A.
The LI was of course capable to achieve that SNR on even smaller signals.
I also designed one low-noise differential amplifier, but that's over 30 years ago .. I'll have to look, which IC I have used, and if there is a successor available.
It was an SSM2016, from PMI, 1988 vintage.
Low noise, low distortion amplifier.
Frank