Hi Frank,
thanks, how did you do it? I measured and it is -19.5mV. This is freaky.
OK, but now I am confused. Why does this offset occur, and how can I
resolve this issue? It might be due to an input impedance of the ADC
that is too low, so that it loads the circuit when actually nothing
should happen, right?
I could probably subtract the 19.5mV manually in software, but there
should be some way to do this externally?
Jens
Am 19.03.2011 13:47, schrieb Frank Bemelman:
Hi Jens,
You only have a gain adjustment, nothing to compensate for offset.
Your opamp has a small offset and is also multiplied by the gain of the
circuit.
At zero current, what voltage do you have on pin 2 of your DAC.
It should be 0V. From your previous measurements I suspect a
small negative offset there, 20mV perhaps.
Best wishes,
Frank
----- Original Message ----- From: "jb-electronics"
<webmas...@jb-electronics.de>
To: <neonixie-l@googlegroups.com>
Cc: "threeneurons" <threeneur...@yahoo.com>
Sent: Saturday, March 19, 2011 1:09 PM
Subject: Re: [neonixie-l] Re: Nixie tube amperemeter
Hi all,
here is the schematic for my amperemeter.
http://www.jb-electronics.de/tmp/amperemeter_schematic.png
Jens
Am 18.03.2011 02:25, schrieb threeneurons:
On Mar 17, 6:13 am, jb-electronics<webmas...@jb-electronics.de>
wrote:
Got any pictures ? I think in pictures.
A quick and dirty schematic of your setup would be nice.
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