Patent ID: 6456903
Filing Date: 2002-09-24
Classification: G05D,Y10T

Abstract:
A circuit for controlling a valve that regulates a rate at which surfactant is mixed with water, which comprises:a signal generator electrically coupled with a first sensor for sensing the conductivity of the water and electrically coupled with a second sensor for sensing the conductivity of a foam solution that includes a concentration of the surfactant; one or more switches used to repeatedly switch between sensing the conductivity of water at the first sensor and sensing the conductivity of the foam solution at the second sensor; a conversion circuit utilizing a single circuit path for converting both the conductivity of the water into a first voltage and the conductivity of the foam solution into a second voltage; and a control circuit for controlling the rate surfactant is released at the valve by utilizing the difference of the first voltage and the second voltage and a control voltage.