Automatic fan switch circuit -- PTC Thermistor

All kinds of electric fans and exhaust fans are one of the commonly used household appliances and are widely used in industrial and agricultural production such as restaurants, shopping malls, stations, warehouses, and food production. In many public places, the temperature varies greatly depending on the flow of people; different types of warehouses, especially warehouses with flammable, explosive, and high-temperature perishable materials, need to be equipped with automatic switching circuits to prevent heatstroke, heat dissipation, and safety and energy saving. the goal of. The PTC thermistor automatic switching circuit introduced in this article can effectively achieve the above-mentioned purpose.

1 Principle circuit
The schematic diagram of the automatic switch circuit of the electric fan is shown in Figure 2.6.1. PTC thermistor RT and RP form a voltage divider, and the switch temperature of the fan can be preset by adjusting RP.

2 Selection of main components
The automatic switching circuit of the electric fan uses a PTC thermistor as the temperature sensing element RT. The standard resistance-temperature curve of this element is shown in Figure 2.