Figure 39-4 In the figure, the IC555 time base circuit is composed of a self-excited multivibrator, and C determines that its oscillation frequency is around 20 kHz, and the output voltage is about 2 to 2.5 times the input voltage (ie, the power supply voltage), and the load capacity is up to 50mA. The printed circuit of the DC booster is shown in Figure 39-5. Figure 39-5 Thermal Cutout,Capillary Type Thermostat,Freezer Used Thermostat,Adjustable Thermostat Foshan City Jiulong Machine Co., Ltd , https://www.jlthermostat.com