用三个发光二极管作电桥的检零指示器

• 作 者: 矢其
• 出 处: 电测与仪表
• 发表日期: 2004年期
• 关键词: 发光二极管 指示器 被测电阻 电桥 电阻电桥 基准 晶体管 电阻 导通 运算放大器

可用三个发光二极管作为0.5%以内电阻电桥中的检零指示器,它可给出直观的读出,特别适用于生产线上的测量,其优点是成本低。电路作用可用图来说明。图中,用简单的发光二极管来指示被测电阻小于、等于或大于基准电阻R_(Ref)。在待测电阻R_(?)近似等于基准电阻R_(Ref)时,晶体管Q_1和Q_2都导通,因为

Three light-emitting diodes are available as zero-check indicators in a 0.5% resistive bridge, which gives an intuitive readout and is particularly suitable for on-line measurements with the advantage of low cost. The role of circuit diagram can be used to illustrate. The figure, with a simple light-emitting diode to indicate the measured resistance is less than, equal to or greater than the reference resistor R_ (Ref). When the resistance to be measured R_ (?) Is approximately equal to the reference resistance R_ (Ref), the transistors Q_1 and Q_2 are both turned on because