Abstract: Time delayed signals are produced by apparatus including an oscillator which provides signals at a constant frequency to a multi-stage frequency divider. One of the stages of the divider is selected and is applied to a multiple-stage frequency divider which provides signals at outputs of various stages thereof. At least a portion of the outputs of the various stages are utilized for controlling the selection of the stage applied to the multiple-stage frequency divider. A digital to analog converter, responsive to the outputs of the multiple-stage frequency divider, provides an analog output signal to a comparator. The comparator provides an output signal when the analog output signal is at least equal to a predetermined voltage.

Abstract: A flame monitoring system includes a flame sensor for producing a flame signal as a function of flame conditions in a monitored environment and flame signal enhancing circuitry coupled to the flame sensor. The flame signal enhancing circuitry has a first response as a function of a first characteristic of the flame signal and a second response different from the first response as a function of a second characteristic of the flame signal and is arranged to combine the first and second responses to provide an enhanced flame signal representative of the monitored flame.

Abstract: A flame responsive system includes a flame sensor, flame signal generating circuitry responsive to the flame sensor and flame signal inhibiting circuitry also responsive to the flame sensor. A fast filter and a slower filter are coordinated so that total loss of flame sensor response results in rapid termination of a flame signal output from the flame signal generating circuitry while reduction of a flame sensor response below a set point causes the flame signal inhibiting circuitry to inhibit the flame signal output.