Hot-wire flow sensor circuit

Abstract

Abstract PURPOSE: To obtain a circuit that facilitates signal processing by providing a circuit that finds the product of a signal showing a time ratio corresponding to the across voltage of a hot wire and a signal corresponding to the across voltage of the hot wire. CONSTITUTION: Of the hot-wire air flow sensor consisting of constant current sources 1 and 5, hot wire 3 and temperature compensating resistance 4, one-side terminals of hot wire 3 and temperature compensating resistance 4 are connected to integrator 8 via resistance 7 and amplifier 9 respectively. While output V 1 of integrator 8 and the output of saw-tooth wave generator 13 are inputted to comparator 10, the output of integrator 8 is inputted to buffer amplifier 22 by way of amplifier 20 and resistance 21 and its input terminal is controlled by transistor 28 supplied with the output of comparator 10 via inverter 27. Thus, since the buffer amplifier outputs a pulse that has amplitude V 1 and a time ratio proportion to V 1 , this pulse is smoothed by low-pass filter 23 to obtain a signal proportional to an air flow rate. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Takao Sasayama
• 👤 Shinichi Sakamoto

Bibliographic Details