As the title suggests, I'm wondering what the effective input parameters are for the analog inputs on the T7-pro.
Reason for this being that I was contemplating the use of a 10:1 oscilloscope probe; the kind that is typically compensated for a 1 MOhm scope input with perhaps 12 pF of capacitance to ground. Will these common attenuating scope probes work properly with a T7-pro? I'm assuming that the input impedance is greater than 1 MOhm and the capacitance is similar, so they should work just fine...but I want to double check...
Thanks,
- Jason
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The simple answer for input impedance of the T7 is 1 Gohm, but this is not a very useful number when dealing with a multi-channel instrumentation amplifier input:
https://labjack.com/support/datasheets/t7/appendix-a-3
The input bias current is a more useful number, but for multi-channel applications you also have to worry about the source impedance slowing down signal settling:
https://labjack.com/support/appnotes/SettlingTime
If you can determine the series impedance of the probe we can comment further, but from Table 2 of the Settling Time app note linked above you can see that you can have very large source impedance under many (but not all) combinations of Range (Gain) and ResolutionIndex.
Keep in mind that scopes are generally designed for speed not accuracy or resolution, so for a probe to "work" with a 1 Mohm scope input it might just have to maintain 12-bit or even just 8-bit accuracy with the 1 Mohm load.