AUTOMATIC TEMPERATURE CONTROL CIRCUIT IN A HIGH-FREQUENCY HEATING APPARATUS

摘要

An automatic temperature control circuit in a high-frequency heating apparatus comprising a differential amplifier circuit receiving at one of its input terminals signals from a temperature-setting voltage circuit and at another input terminal signals from a thermister provided with a heating needle which contacts with a load to be heated and amplifying the difference between said two signals, and a voltage control circuit taking said amplified difference of signals and controlling a power voltage in a high-frequency amplitude control circuit. A high-frequency power amplifier circuit in the heating apparatus is thereby controlled so that the temperature of the heating needle at its contact point with the load can be kept under a predetermined degree of temperature.