Relay priority control

Discussion in 'The Projects Forum' started by erich_7719, Nov 9, 2009.

  1. erich_7719

    Thread Starter Active Member

    Oct 14, 2009
    I am putting together a Vivarium to which I have automatic controls for a mister (to simulate rain), A fogger (to produce a mist fog), and a thermal control (to control cooling fans).

    So here is what I need help with I want them to only run on a priority scheme Like if mister is running the fogger and fans cannot run, and if the fan or fogger is running and the mister calls to run the mister takes priority and stops what ever was running then the mister starts.

    Attached is the schematic to the point I hit a "road block" and the truth table of the desired output. All outputs will go to transistors that will trigger the respective relay.

    I also realize now after designing the schematic that the 3-input Xor will have to be replaced some how for the desired output.

    Hopefully this is enough information and thank you in advance for any suggestions you may have.
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    If your truth table is correct, then

    Bo=not(Ai) AND Bi (two input AND gate, one inverter)
    Co=not(Ai) AND not(Bi) AND Ci (three input AND gate, and a new inverter)
  3. erich_7719

    Thread Starter Active Member

    Oct 14, 2009
    Thank you, that was much simpler than what I was trying to do, as long as I ran the table right:)