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Voltage controlled current Source

Hello NI mentors,


Thank you for your usual support. I want to discuss an idea. My purpose is to supply the pt100 a current  0 to 20mA to study its characteristics. I have NI cRIO 9024 and a Cseries Module NI 9263(output voltage module). The idea is to connect this C series output to Howland current source circuit and uses the its output current as an input to pt100. 

I need a current range 0 to 20 mA. Can i control this output current of Howland circuit by using NI 9263 output voltage???

Thankyou for reading the post. 

Your answers are needed.



Best Regards 


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Message 1 of 22

Can you guide me which power supply you used for current supply?

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Message 2 of 22

This is an old post from someone who hasn't been on the forum for 11 years, but you might

consider using a B&K Precision 19108B which can source 30 Amps.

It can be controlled via it's USB port (USB Serial).



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Message 3 of 22

Anyone if can answer, kindly help me. Howland Voltage controlled current source circuit is attached within pics.

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Message 4 of 22

Hello Zohaib,


The USB-9263 cannot be diectly used to generate a 0-20 current. You could buy a 5B or 8B module (or something like it) that could convert the 0-10VDC signal to 0-20. Then you could do what you are asking.



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Message 5 of 22

I am doing an experiment to study pt100 characteristics for which i need 0 to 20mA current input. The hardware i have NI9024 cRIO controller with chassis and NI9263 C Series module. I need to develop voltage controlled current source.

For that i have simulate a circuit as per attached simulation in multisim. When input voltage is changed 0 to 1 V, the respect load current is changed 0 to 20mA range.


The question is can i use NI 9263 module to vary input voltage to this circuit in range of 0 to 1V, keeping in mind that 9263 drive current is 1mA.

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Message 6 of 22

Then you need to buy an intermediate signal conditioner that converts from 0-20 ma to 0-10VDC. Again a simple way to do that would be to get a 5B or 8B module or something like it to do the signal conditioning.  The DAQ card you are using is not made for current measurement.

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Message 7 of 22

Dear Tim,


You are not understanding my question. It is not a DAQ card. NI9263 is C series module that is used as voltage output 0 to 10VDC. I am saying can i use this voltage as an input to my circuit for getting current in range of 0to 20mA. 


2nd thing is can you explain what is 5 B or 10B ?

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Message 8 of 22

You are not understanding my answer:


The 9263 can generate a 0-10VDC output. It is not designed to provide a 0-20 ma output.


A 5B or 8B is an intermediate signal conditioner that will do the conversion of the 0-10VDC output to 0-20ma signal. You can get these from NI, Analog Device or Dataforth. You do have other options as well. This devices will run you about $250 per channel. You need to specify the inout and output for the signal conditioner so you get the correct one. You could also make your own.


The 9263 module will not send a 0-20 ma signal.


I do believe that I am understanding your question and I am trying to answer your question.

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Message 9 of 22

Despite your insistence, the NI-9263 is also a DAQ device in the broader sense, although one with analog outputs. You could of course select the right C series modules that directly deliver you a 0-20mA value. For instance the NI-9265 gives you 4 channels of 0-20mA outputs. I'm not sure if your schematic is a fully functioning voltage to current converter. If it is I don't see why you couldn't do what you want, but I would try to make the input range 0 - 10V rather than 0 - 1V, simply for better accuracy. But that is up to you to verify this circuit to work properly and within the accuracy requirements you have.


5B is a product range from Analog Device for modular signal conditioning modules: They have specific V->mA converter modules although there the range is typically 0-10V -> 0 - 20mA, which I would think makes more sense.

Rolf Kalbermatter
Averna BV
LabVIEW ArchitectLabVIEW ChampionLabVIEW Instructor
Message 10 of 22