一种功能优良的三态逻辑指示电路

这种功能优良的三态逻辑指示电路由555IC集成定时器、逻辑电平阈值调节设定电路、逻辑指示电路构成。输入为高阻状态时555IC工作在多谐振荡器状态,发出蜂鸣声,数码管交替显示L,H,呈闪烁状态;输入高电平或低电平时,555IC工作在施密特触发器状态,数码管显示H或L,以示输入信号为高电平或低电平。电路的电源电压为3~18 V,适用于各种类型的数字逻辑电路的逻辑电平判断。给出了调节设定逻辑电平阈值的计算公式和部分电路参数,使逻辑电平界限清楚,判断确切。该电路可做成三态逻辑笔或装置在万用表、数字逻辑实验箱中使用。

A kind of function fine tri-state logic indicating circuit

This kind of function fine tri-state logic indicating circuit is composed of 555 integrate timer,logical level threshold value adjustment circuit and the logic indicating circuit.The 555IC works in multivibrator condition,sending out the buzzing sound,with digital tube demonstrating L,H glittering,to show the input signal is on high impedance condition.When the input is high or low,the 555IC works on the Schmitt trigger condition,and the digital tube demonstrates H or L,which shows the input signal is at the high level or the low level.The circuit supply voltage is 3~18 V,suitable in logic level of kinds of digital logical circuits.It supplies the account formulas and partial circuits parameters of the threshold value for adjusting and setting-up logic level.It makes logical level boundary clear and well-judged.This circuit may make a tri-state logic pen or is installed in the multimeter and the digital logical experiment box.