Transducer Conversion (Resistive to ICP)

I have a String Potentiometer Transducer. Normally our Data Aquisition systems supply the voltage to these transducers with +v and -V lines and we receive a signal on our +sig and -Sig lines... But we recently have a new Data Aquisition which uses Constant Current Technology also known as ICP. Im not really sure how Constant Current works but i know that instead of 4 wires it uses only two wires which excites the transducer and returns the signal.

So what i want to do is convert my Resistive 4 wire transducer into a ICP (Constant Current) 2 wire transducer.


Does anyone know how i can so this?
An can anyone explain Constant Current to me?

The only ICP devices that I am even remotely familiar with (and I have only read about them) have piezoelectric transducers, and they use the current source to provide a bias current to the output buffer (generally a FET source follower). The output voltage can then be read off the same line that provides current to the buffer.
Check out **broken link removed**. Also, do a Google search on "icp constant current" (without the quotes).

What does your transducer measure?

CURRENT SOURCE

I think you want to say current source, so you must have a bridge and you get the differential for amplifying it! You could make it with opamps or specializaed and linearized IC's like the TEXAS XTR. I think that maybe answer your question. :roll:

measures the distance the string is pulled out.... or you could say it measures the distance between two objects in motion.... Also know as a displacement transducer

Below is a possible two wire implementation. The biggest potential problem I see is that wire and wiper resistance are in series with the actual resistance to be measured. These can prpbably be calibrated out.