A control scheme is described for improving the performance characteristics of an on/off electrothermal process by means of a model of the process. A /though the process itself operates on open loop, the switching sequence is closely controlled by the operation of a closed loop incorporating the model and the process controller. The temperature drift may be virtually eliminated by representing the model electronically. The scheme proves useful when the process has a large inherent delay or when it is not convenient to derive transduced signals from the output temperature for the purpose of control.
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