While we might all be quick to grab a microcontroller and an appropriate sensor to solve some problem ... This heating circuit, for example, uses a MOSFET as a heating element and as its own ...

The MOSFET in Figure 1 is used as both a heater and a temperature sensor in a thermostatic circuit. Figure 1 Circuit diagram for using a MOSFET as a thermostatic heater. The circuit can be used as a ...

A split system heat pump's defrost sensor is used to detect ice buildup ... the defrost thermostat completes a circuit to the defrost board (the sensor closes the circuit). The defrost board will then ...

This is exactly what the circuit in the figure does. Q1’s drain supplies heating; heating current I to the sensor/heater wire (please ignore for a moment the minor contribution from start-up resistor ...