| 摘要 |
<p>PURPOSE:To maintain the resistance value of a metallic wire at a prescribed value despite a change in ambient temp. by selecting the ratios of the temp. coeffts. of resistors used in a bridge circuit of a hot-wire flowmeter. CONSTITUTION:The potential difference at points (c), (d) of connection with a change in the resistance value of a metallic wire RH contributes to a change in the base voltage of a transistor Q1, and the current supplied from the TR Q1 to a bridge circuit increases or decreases the resistance value of the wire RH so as to maintain the same at a prescribed value. The ratio of the temp. coefft alpha2 of a resistor R2 with respect to the temp. coefft. alpha1 of a resistor R1 is determined at around alpha1/alpha2=(R1+RK)/R1, whereby the influence by the ambient temp. of the resistors R1, R2 is eliminated.</p> |
