Commercial electric blankets generally have two temperature levels: high and low. When in use, it is switched to the high temperature gear, and will always be awakened by heat after falling asleep; When you switch to low temperature, sometimes you wake up and feel that the heat is not enough. Therefore, the author has made this kind of electric blanket temperature controller, which can control the temperature of the electric blanket in a suitable range.
working principle:The circuit is shown in the figure below. IC in the figure is NE555 time base circuit; RP3 is a temperature regulating potentiometer, and its sliding arm potential determines the trigger potential V2 and threshold potential VF of IC, and V5 = VF = 2vz. 220V AC voltage is reduced by C1 and R1 current limiting, rectified by D1 and D2, filtered by C2 and stabilized by DW to obtain a voltage of about 9V for IC. Turn on the power at room temperature because V2 has been adjusted
Component selection:PNP germanium tubes such as 3ax and 3aG can be selected for BG1; BCR uses small plastic encapsulated bidirectional thyristor above 400V, and other components can be selected according to the icon.
Key points of production:The thermal sensor BG1 can be led out with a temperature resistant thin flexible wire, and installed into an aluminum shell of a capacitor together with the pin connector. The thermal conductive silicone grease is injected to make a temperature probe. When in use, the probe can be placed at an appropriate position.