CONSTANT-TEMPERATURE CONTROLLED CIRCUIT FOR AN ELECTRIC HEATING DEVICE

摘要

This disclosure discloses a constant-temperature controlled circuit for an electric heating device, comprises an AC/DC switching circuit, a heating strip and a temperature controlled circuit; the heating strip comprises a heating line, a temperature sensing line and a NTC layer located between the heating line and the temperature sensing line; the temperature controlled circuit comprises a central processing unit, a voltage sampling circuit, a TRIAC circuit and a load detection circuit. Compared with existing technology, in the heating process, resistance of the NTC layer decreases as the temperature increases, since the heating strip and the voltage sampling circuit are connected in series, the output sample voltage of the voltage sampling circuit reflects the current temperature, and then the central processing unit outputs controls to switch the TRIAC circuit on or off according to the sample voltage, keeping the device at a constant temperature. Constant temperature control is realized.

主权项

1. A constant temperature controlled circuit for an electric heating device, comprising:
an AC/DC switching circuit, which is used to switch an external alternating current into a +5V direct current; a heating, strip, which further comprises a heating line, a temperature sensing line, a NTC layer located between the heating line and the temperature sensing line, wherein an input end of the heating line is connected with a fire line of the external alternating current; a temperature controlled circuit which further comprises a central processing unit, a voltage sampling circuit, a TRIAC circuit and a load detection circuit; wherein the +5V direct current provides a working voltage for the central processing unit, a first end of the TRIAC circuit is connected to an output end of the heating line, a second end of the TRIAC circuit is connected to the load detection circuit, the load detection circuit detects whether a load is connected and outputs a detected result to the central processing unit, the voltage sampling circuit is connected to the temperature sensing line and a sample voltage input end of the central processing unit to output a sample voltage to the central processing unit, a control output end of the central processing unit is connected to a control end of the TRIAC circuit, the central processing, unit outputs a control signal to the control end to switch the TRIAC circuit on or off according to the sample voltage and a corresponding voltage grade of a temperature grade.