| 摘要 |
A hot wire flow rate measuring apparatus comprises a platinum wire sensor (4) and a thermistor (5) in the upper limbs of a bridge circuit whose lower limbs comprise resistors (16, 19). The thermistor (5), together with a linearising resistor (17) and a scaling resistor (18), is connected into the bridge circuit via a potential divider (20, 21). A differential amplifier (22) and a transistor (23) control the supply of power to the bridge circuit so that the platinum wire sensor (4) is maintained at a higher temperature than the thermistor by a fixed temperature difference. <IMAGE> |
