Fabrication of hot-wire probes and electronics for constant temperature anemometers

Abstract

The purpose of this paper is to discuss the construction of constant temperature hot wire anemometers. Different options are analyzed for the fabrication of sensors and electronics. A practical and simple method is developed to manufacture the probe and associated electronics. The fabricated sensor has a diameter of 2 µm and approximately 500 µm in length. The associated electronics are designed to keep the sensor working at a constant temperature and allow the indirect measurement of speed. The design is simple, inexpensive and highly flexible regarding its use and modifications. The dynamic tests performed and the comparison with a commercial model shows a satisfactory performance. The unit built also includes an option for testing with a square wave, which is generated internally, and a comparator mode to measure the resistance of the sensor.