Temp. control for heating element - determines resistance and hence temp. from current and voltage, to control triac switch

摘要

The temperature regulator, for controlling an electrical heating element, determines the element's temperature by measuring the current flowing through it and the voltage across it in two channels. The channels consist of input transformers coupled to the element and feeding two rectifiers. The rectifiers' outputs are combined into a single signal representing the resistance of the element -- and therefore its temperature. This signal is compared with a reference. The comparator's output is amplified, transformed and used to control the triac switch in series with the heating element.