Electric contact mercury thermometer constant temperature control circuit 2

It can be used in small thermostatic control boxes for home incubation. The heating element uses several 220V/25W
light bulbs or heating wires.
    Electric incubation temperature requirements: When the ambient temperature is 20°C, the control temperature
is set to 38°C; the control accuracy does not exceed ±1°C; the heating time
is not more than 2 hours; the temperature at each point of the egg tray should be as small as possible, such as less than 1°C.
In fact, the difference between the upper and lower temperature limits (that is, the control accuracy) is extremely small, about
+0. ltC.
    According to the component values ​​shown in the figure, when Rs-5.lkfl,
the conduction angle of the thyristor V is approximately 130°.
    Electric contact mercury thermometer KP is selected from 0-50℃, and the minimum
graduation value is 0.2℃.