Abstract: An oxidant flow conduit having a restriction and branching downstream of the restriction to provide a primary flow conduit for supplying oxidant to a nebulizer and an auxiliary flow conduit having an adjustable valve for supplying oxidant to a mixing chamber is provided. A differential pressure transducer measures the pressure drop across the restriction to provide an output signal. A primary fuel conduit is provided having a pair of restrictions with an adjustable valve for supplying fuel to the mixing chamber. A boost conduit having a restriction is connected to the primary fuel conduit and between the restrictions providing for supplementing the fuel to the mixing chamber when a different fuel mixture is used. A differential pressure transducer measures the pressure drop across the pair of restrictions to provide an output signal. A square root linearization operation is performed on each signal in a microprocessor and modified output signals drive respective fuel and oxidant digital displays.

Abstract: Power is applied to an electrical element in maintaining a thermal system at stabilized conditions and a feedback signal is derived to control the electrical input to the heating element by linearly combining functions of the current through the heating element and the voltage drop thereacross respectively. In one embodiment, each of the linearly combined functions in the feedback signal can be varied independently to change the stabilized conditions of the thermal system, while in another embodiment a microprocessor is incorporated to provide such variation for a sequential range of stabilized conditions.