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三位半A/D转换器5G14433因有BCD码及其它功能输出,在数字仪表中被广泛地应用。但其满量程输出的数字仅为1999,当仪表的量程超过2000时,便无法利用它的首位,只得使用后三位,将三位半的A/D转换器降格为三位,使仪表的分辨率及精度降低一个数量级。这在器件功能上是一种浪费。如果对线路稍加改进,就可以使它的量程扩大至2000以上。原则上可以用三位半A/D转换器制用四位的仪表。其改造成为显示数字3999的数字仪表最为简单易行。下面介绍本人在研制某控温仪表过程中利用5G14433的一些输出功能,配合少量逻辑电路和电子模拟开关,用三位半的A/D转换器做成测量范围为-199.9～+399.9℃的数字仪表的一些尝试。图1为本仪器有关部分的电原理图。其中测温桥路的输出信号经放大及非线性校正后送至三位半A/D转换器5G14433,经5G4511译码后显示温度数值。电
Three and a half A / D converter 5G14433 BCD code and other functions due to the output, is widely used in digital instruments. However, the full-scale output of the figure is only 1999, when the instrument’s range exceeds 2000, it can not use its first place, only to use the last three, the three and a half of the A / D converter downgraded to three, the instrument’s Resolution and accuracy is reduced by an order of magnitude. This is a waste of functionality on the device. If you slightly improve the line, you can make it scale up to 2000 or more. In principle, four and a half meters can be used with three and a half A / D converters. Its transformation into a digital 3999 digital display is the most simple and easy. Here I introduce some of the temperature in the development of a temperature control instrument using some of the output function of 5G14433, with a small amount of logic circuits and electronic analog switches, with three and a half of the A / D converter made of the measurement range of -199.9 ~ +399.9 ℃ Some attempts at the meter. Figure 1 is the electrical schematic of the relevant part of the instrument. One of the temperature measurement of the bridge output signal is amplified and non-linear correction sent to three and a half A / D converter 5G14433, 5G4511 decoded temperature values. Electricity