4 Replies Latest reply on May 17, 2019 11:03 AM by s1buell

    4-20ma Circuit Review


      Hi everyone I have made this 4-20ma circuit and would like to have a review and get some feedback before I make the pcb.


      Here is the reference circuit


      Under the receiver area



      I don’t have much experience with 4-20 and started this project to change this…..


      Here is one channel in the circuit



          • Re: 4-20ma Circuit Review

            Hi Tom,


            It's hard to see from the schematic (the text is small and has reference marks over it), is this KiCAD or something? Maybe there's a PNG export (or some other image file) that is clearer. The URL you've mentioned doesn't show a complete schematic, just simplified, so it is missing the decoupling capacitors, sthose would need to be added. If you can find a reference design, or some evaluation board from AD (usually those have full schematics) then that will be better. Also, then there is the advantage that you can also look at the Gerber files from their eval boards, to see if they've done anything special. It reduces the risk a lot to try to glean from the reference designs (just noticed at the top of the page they mention a link to download the design files, so those should be inspected).

            6 of 6 people found this helpful
          • Re: 4-20ma Circuit Review

            Yes, I just seen that last night after I posted (Parts, missing..... lol). I thought something was strange.


            I like the proto board they have. I’m going to pause this part of the project and buy the proto board to test with our sensors. if it works I will build this board and do some integration work (CPU, Radio etc).


            4-20 is a new area for me.


            Stay tuned!


            I will start a new thread for the CPU project I have going. I need to get this CPU up and running.

            • Re: 4-20ma Circuit Review

              Ok, posted the CPU project.


              If anyone has any experience with programming these SAD21`s please have a look if you have time


              Thanks again!