Process and circuit for controlling a gas burner

A circuit for controlling a gas burner, comprising:

• a measuring electrode;
• a control circuit, said measuring electrode sending an electrical measured variable (U) signal corresponding to a combustion temperature (lambda value) of the burner to the control circuit, said control circuit including a comparator comparing a current said electrical measured variable signal with a selected electrical set point of a setting means and adjusts a gas-to-air ratio of the burner to a lambda set point corresponding to said selected electrical set point, a change-over switch for interrupting adjustment by said setting means and a ramp generator for reducing the gas-to-air ratio beginning from a lambda value of >1 to a lambda<1, wherein said electrical measured variable (U) is varied to form a curve, a recognition and memory circuit for detecting a value of the measured variable at a maximum of the curve and for storing said values and adjusting means for adjusting said selected electrical set point based on said value.

A process in accordance with claim 17, further comprising:

• stopping said combusting when said maximum of said actual ionization signal is outside a predetermined range.