DC Circuit question

Discussion in 'The Projects Forum' started by IGluIt4U, Aug 11, 2006.

  1. IGluIt4U

    Thread Starter New Member

    Aug 11, 2006
    I have a problem, need some advice.. I have a circuit that consists of an E/P converter (voltage to pressure) and a signal isolator to generate a 0-10vdc analog signal used as an input to the E/P converter. The converter also requires that a 24vdc power source be applied. I have a 24vdc power supply to generate the needed voltage.

    Herein lies the problem/question. The E/P converter only has one negative lead for a common negative between the two voltage sources, but my voltages do not share a common negative. If I use the 24V negative, I don't get my 0-10V input to track pressure and generate output... if I use the 0-10v negative, I get a tracking signal, but no 24V power to the E/P converter....

    Can I tie the negatives together without affecting the signal isolator's output (0-10Vdc) or the power supplies output (24Vdc)?? Or am I going to create unwanted crossover??
  2. beenthere

    Retired Moderator

    Apr 20, 2004

    Without a common reference, the circuit isn't going to work, as you have found out. Check the specs on the isolator. The output should be the isolated part, so making its ground common with the 24 volts supply should work.