Automatic controller for electric iron

When using an electric iron, since the iron has no safety protection device, if you are not careful, you will damage your clothes. For this reason, a safety control circuit is installed on the basis of the YK3-50D 500W automatic temperature control electric iron to make a safe automatic temperature control electric iron. If the electric iron is placed on the clothes and the person leaves without turning it off, it will automatically cut off the power supply after about 2 minutes to avoid damaging the clothes. If you finish using it and put it upright on the table and forget to turn it off, it will automatically cut off the power supply after 15 minutes. This is safe and saves electricity. After the iron stops working due to the action of the safety control circuit, if the user wants to use it again, he only needs to hold the handle, the protection circuit will reset, and the iron will automatically start working, which is very convenient to use.

Component selection: IC1 (LM393N) is a high-precision dual voltage comparator. The functional block diagram of the lead-out terminal is shown in the figure. Only one of the comparators is used in this circuit. BCR1 can be selected with a withstand voltage greater than 400V. The rated current depends on the specific power of the electric iron, and a large margin is left. Here, 6A is selected, and a 30mm×30mm×2mm aluminum plate for heat dissipation is installed. LED1 can choose infrared light-emitting diodes such as SE303. The smaller the leakage of C3 capacitor, the better. It is best to use tantalum electrolytic capacitors. The models and parameters of other components are shown in the figure. It is advisable to use ultra-small components.