Flame safeguard systems that utilize a flame sensor and amplifiers for control of valve means in a burner system have been utilized for many years. Typically these systems use discrete component electronic systems in their amplifiers, and the amplifiers in turn ultimately control a relay. The relay in turn is used to switch power for an electromagnetically operated fuel valve. As the electronic and electromechanical types of flame safeguard systems evolved, the reliability and safety of the systems has been of prime concern. As a result of this concern, systems and equipment have been developed which are very reliable and allow the flame safeguard system to accurately and reliably control the operation of the main fuel valve to a burner in response to the presence or absence of flame at the burner.
In recent years microcomputer based systems have evolved. These systems utilize very small and complex integrated circuits. The microcomputers, while having many capabilities, have a frailty in that they are subject to many more types of failures than discrete component electronic circuits. The utilization of a microcomputer in a flame safeguard control system requires a high degree of care, and the use of special safety systems. In a prior art type of microcomputer based flame safeguard system as disclosed in U.S. Pat. No. 4,298,334, assigned to the assignee of the present invention, the microcomputer and flame amplifier both controlled power to the main fuel valve relay. This type of redundant circuitry is expensive, and may be improved upon by the present invention.