Anemometer with an Intermittently-Heated Transistor as a Sensor

Abstract

A thermal anemometer using a transistor as a sensor has been constructed and tested. The sensor is intermittently heated so that its temperature goes up and down periodically between two prescribed limits. Since the time required for the temperature to rise to the upper limit due to the heating depends on the speed of the surrounding fluid, we can use the time detected to determine the velocity of the fluid. The anemometer works under small temperature differences between the sensor and the fluid. It is highly durable, and shows high sensitivity over a wide range of fluid speeds.