I am at a road block on my current project. So far I have an AC timer that will trigger 3 times a day and turns on a solenoid and allows flow of a substance onto a resistive pad that varies with weight. Then I have a comparator that has a reference value and a measured value. The "measured" value changes with the resistive pad. It is setup so that when the "measured" value reaches the value of the reference it will trigger a fet and shut off the solenoid. Now this is where I'm stuck. I need this circuit to only operate once. Meaning that I want it to dispense until the "measured" value is met, shut off the solenoid, and then wait until the next time it gets triggered. I feel like there is something very simple that I'm missing but I can't think of it. Let me know what you think and if you need more info. Thanks!