Don't build it.....

Phoenix Contact makes a small DIN rail mounted module that will convert just about any millvolt and/or amp signal to any other millivolt and/or milliamp signal.

Check out this link: http://eshop.phoenixcontact.com/phoenix/logon.do?user=anonym&general=enen

And search for part 2810913 MCR-C-UI-UI-DCI

Using DIP switches it can be set up to change just about any signal into any other signal. It's very nice. No idea of cost but I was about to buy one to solve a problem that I have. I think they run a couple hundred bucks....

I think they also make a unit that can be programmed for unique input and output performance.

RSlater,
RSmike