Hello Eli,
Thank you for sharing your work.
I had a quick look at your design on Github but it turned out to
be a very superficial look because the schematics are only in
Kicad format.
I know Kicad is free but the time to install it and get to know
it isn't.
It would be very helpful if you were also to present the
schematics as .pdf which I think pretty much everyone has a way of
reading.
Of course it's your project and your time and I am well aware
that I'm asking you to do something extra - I do think you would
attract more interest and maybe more useful comment.
Michael Kellett,
MK Electronics Ltd.,
Unit 4,
Greenlaw,
Castle Douglas,
DG7 2LH,
01556 506999
07968 111148
On 06/09/2022 23:13, Eli M wrote:
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Below are my accuracy test plots-- of course take everything with
a grain (or handful) of salt because I don't have a calibrated set
of resistors/capacitors, and I'm still a student learning the
field. The raw data is all in the github with the scripts to make
these plots (written in Julia).
The fact the board only has two shunt resistors is a major
limitation of the design for a general audience. I almost measure
components within 100m-10k range so 100 Ohm shunt does the job. I
figure anybody willing to populate a PCB and use a DAQ should know
the application well enough to pick the right resistors for the
job.?
My plan is to make a set of loads in shielded enclosures with BNC
connectors on each such that the connection is repeatable on
different meters. The Kelvin clips are a good start minimizing the
effect of contact resistance, but still end up being moved
changing the parasitic values, which is especially harmful to the
measurement at 100 kHz. Then I'd gladly send the loads to whoever
would like to test and there can be a level of certainty that
there are no connection errors. Also using low tempco resistors is
probably important for this. Now that I think of it, I'll probably
make a design shortly and start a new thread on the matter because
it is a bit tangential, and I think there are plenty of readers
who would have helpful insights on it.?
-Eli
1kHz resistor measurements:
10kHz resistor
measurements:
100kHz measurement:
Capacitors @ 10kHz: Ceramic
below 1¦ÌF, radial film 1¦ÌF and above
