Circuit diagrams and schematics - Electronic projects

Bridge circuit contains two resistors lOO-ohm (R3 and R4), and two thermistors (Tl and T2). At room temperature, the resistance of T1 and 1’2 is about 2000 ohms. When they are each heated to 150 °C by an RNA 10 current, the resistance value decreases to 100 ohms. So. the four elements include a bridge [...]

This simple circuit uses an incandescent lamp to detect airflow. With the filament exposed to air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As air flows over the filament it cools down, thus lowering it’s resistance. A comparator is used to detect this difference [...]

A sensitive and reliable way to measure airflow is to exploit the predictable relationship between airspeed and the heat dissipated by a sensor exposed to the flow while being held at a constant temperature differential above ambient. The power required to maintain the elevated sensor temperature is proportional to the square root of the airspeed [...]