本文介绍一种新颖的电子密码开关电路,该电路采用两片CMOS数字集成电路芯片,利用S0～S9共10个按钮开关输入密码,用其中的4个按钮输入5～7(可调)位有效密码,另外6个按钮用来输入保护密码,同时在输入密码时必须在限定的时间内完成和必须按照预定的顺序输入。该设计具有电路简单,保密性好,密码位数设置更换方便和工作稳定可靠等优点。 工作原理:电路如图1所示。IC1是一片“模拟开关”芯片,在该芯片中有4个完全相同且可独立控制的模拟开关(MS1～MS4)。IC2是一片“十进制计数/分配器”芯片。其中,将IC1中的MS1用做延时开关使用,为此,在MS1的控制端并联接有C1和RP1阻 This article introduces a novel electronic password switch circuit, the circuit uses two CMOS digital integrated circuit chips, the use of S0 ~ S9 a total of 10 button switch password, with one of the four buttons 5 ~ 7 (adjustable) effective Password, the other six buttons are used to enter the protection password, and at the same time the password must be entered within a limited time and must be entered in a predetermined order. The design has the advantages of simple circuit, good confidentiality, easy setting of password bits, stable and reliable operation, and so on. Working principle: circuit shown in Figure 1. IC1 is a “analog switch” chip, the chip has four identical and independently controlled analog switch (MS1 ~ MS4). IC2 is a “decimal counter / divider” chip. Among them, the MS1 in IC1 used as a delay switch, for this reason, in parallel with the control of MS1 C1 and RP1 resistance