A hot-film anemometer circuit operated at constant current.

In this study it is presented a hot-film anemometer circuit, operated at constant current, constituted of a Wheatstone bridge and a high-gain differential amplifier. The sensor element, different from the usual hot film, is a temperature gauge of thermo-resistive conception, in which a nickel film is deposited above a substrate forming a 3,2 x 3,2 mm grid and 5 ?m thick. The probe, being cheap and easy to construct, has a sensitivity of the regular anemometers. Several measurements of velocity were made of an air flow, in the range of 2 – 12 m/s. The calibration curve showed the maximum deviation of 10% from the experimental data. It was also investigated the dynamic response of the instrument, the fluid flow velocity.