计算器模拟信号输入电路设计

The Design of a Calculator Analog Signal Interface Circuit

利用 4(1/2)位 ICL7135A/D 转换器设计了一种接口电路.模拟信号送到ICL7135A/D 转换器后,转换成5位8421 BCD 码,再送到寄存器中暂存起来.顺序脉冲发生器产生顺序脉冲信号控制寄存器将5位8421 BCD 码从高位到低位依次取出送到译码器中.经过译码器译码.把数字信号变成单个脉冲.通过电子开关从高位到低位依次送到计算器中做运算处理.接口电路简便、实用,配上称重装置可制成简易计价称.

This paper presents the design of a type of interface circuit using a 4 1/2bit A D converter.Analog signals are sent to a ICL 7135 A/D converter and changed into a 5 bit 8421 BCD code,then stored by a register temporarily.Sequential pulse signals generated by a pulser control the register so the 5 bit 8421 BCD code is transmitted to a decoder sequently from a high order to a low order bit.The decoder changes the digital signals into single pulse signals,which will be sent to a calculator in turn for calculating and processing.This task is fulfilled by an electronic switch. This calculator analog signal intcrface circuit is simple and practical.If a weighing device is provided,a simple value-count weigher may be developed.