AD2 Ehnacement Milliohmeter Version 2

[Jon Frey]

In researching simple circuits for low resistance measurements I cam across the attached design

Low ohm Measurements.pdf

It seems  elegant and well suited to enhancing the AD2 and would be a simple add on board Several resistors and an op amp, as shown but may need a digital voltage level shifter if that AD2 output is to0 limited.

However the software requirements are beyond my limits. Can it be done in scripting or would it need a new instrument in Waveforms ?

 

I will share a build with anyone willing to help

Might be something for Digilent to look at ?

 

 

[darth458]

I'm not volunteering but it would seem that you can use the two DAC outputs instead and they ought to be well behaved. Also you don't need the bipolar to unipolar

converter. I will try to throw together an acquisition code in the next few days for you but you haven't said anything about your software environment. This project involves

some post-processing. Are you able to do that once you have the ADC data?

[attila]

Hi @Jon Frey

Is the Impedance Analyzer interface in the WaveForms app suitable for such measurements?

[Jon Frey]

Impedance analyser wont work as two outputs are needed

 

I was hoping to use logger to run script/outside program and do any post process math

 

It may even be possible to use Analog Parts kit hardware included in Digilent parts kit to do the whole job.

Checking amps in the kit,since do not need  to convert amp output

Put component count as tiny to get microamp resolution

[darth458]

So are you saying that you have no code development environment? You want to script the thing using digilent supplied tools then save the scope output to a file?

[Jon Frey]

Wanted to stay within Digilent tools and  use the logger application  for triggering,control and display

From than I can save,record over time or display using the logger application itself.

However I don't see a one shot measurement, or a one sample selection in the application, so unless we can incorporate/accommodate the sampling function internal to the app, it may not be usable.The record time and update rate are fine , we can adjust update rate  for the run time of the special script, but the minimum samples is 10.

I suppose that might still be OK if the data is stable in memory after we run the script sequence, so that the extra sample sequence is harmless.

Calling multiple waveform applications , while scripting in another is unclear to me.

(Controlling AWG1,AWG2, Scope from logger script )

Also unclear is possibility of calling routines  developed using the SDK from within a script.

The only programming environments I have used are Octave and Python(<3.0)

[attila]

Hi @Jon Frey

The Logger in WF v3.8.2 lets you set sample buffer as low as 1.

I would need a bit of "free" time to study the document, but if you already did this and tell me what measurements/ math functions you need, I might be able to help you faster in implementing script for this. 

[wna]

Could a lock-in amplifier be done with AD2 without any external components, such as this one for myRIO?

http://sine.ni.com/nips/cds/view/p/lang/de/nid/212768

[Jon Frey]

It will be a few weeks before I can look at this virtual instrament ,I am traveling and dont have labview available

Attila would be best suited to answer

I do recall some conversations stating you cant reprogram AD2 FPGA, but may not be necessary

This thread keeps getting better,that would be an excellent function for many measuremnts

[attila]

Hi @wna

See the following post: