Simple and practical analog temperature control circuit principle
The temperature control circuit is mainly composed of power supply part, temperature detecting component, signal amplification, proportional integral, voltage comparison, phase shift trigger control relay, over temperature protection, heating furnace and LED display. The circuit structure is shown in Figure 1.
Figure 1 circuit composition diagram
2.2 Each circuit design
2.1. 1 power circuit
The devices that require DC voltage in the temperature control circuit are operational amplifiers and electronic information display modules. The voltage is rectified and filtered by a 220V AC voltage. The output to the three-terminal regulator is obtained. Its circuit is shown in Figure 2.
Figure 2 Power circuit diagram
2.3 Input temperature signal amplification and temperature compensation circuit
The temperature sensor is collected by using a temperature sensor, nickel-nickel-chromium-type K-type thermocouple as a temperature sensor. The temperature signal is mV level, and the actual measurement needs to be amplified. The thermocouple measurement temperature signal is affected by the working temperature and the free end ambient temperature, so the compensation signal is needed in the measurement to eliminate the influence of the ambient temperature change on the temperature measurement.
The specific circuit is shown in Figure 3.