Burner fuel supply control signal generating device

In a system for generating a control signal for supplying fuel to a burner comprising flame detector means for providing a voltage responsive to detection of a flamae and a circuit for generating said control signal responsive to detection of a flame by said flame detector means, whereby failure of elements of said circuit inhibits production of said control signal;

• the improvement wherein said circuit comprises an astable multivibrator consisting of a field effect transistor with means regeneratively interconnecting the drain and gate of said field effect transistor, so that output oscillations by said multivibrator is dependent upon the potential at the gate of said field effect transistor, and resistor means connected to apply said voltage to said gate, so that said multivibrator oscillates only when said flame detecting voltage has an amplitude between determined values, and means deriving said control signal from said output oscillations.