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人类已开始进入了信息时代,联入因特网几乎成了赶上信息时代的代名词。许多家庭和个人上网的方式一般是拨号连接入网,即通过调制解调器(Modem)和电话线路访问因特网。当你坐在计算机前正准备登录上网工作时,如果有人拿起电话机来拨号,那么它就会影响Modem的正常工作。下面介绍的电路既能使你免除Modem通信的干扰,还可以提醒你有外面的电话打入。 附图所示电路中,K为单刀双掷转换开关,电阻R1和稳压二极管D2组成直流限幅稳压电路,电阻Rz和发光二
Human beings have begun to enter the information age, joining the Internet has almost become synonymous with the information age. Many families and individuals access the Internet through dial-up access to the Internet, ie through the modem and telephone lines. When you sit in front of the computer is preparing to log on Internet access, if someone pick up the phone to dial, then it will affect Modem’s normal work. The circuit described below will not only make you eliminate the interference of Modem communication, you can also remind you to have an incoming call. In the circuit shown in the figure, K is a single-pole double-throw switch, the resistor R1 and the zener diode D2 form a DC-limiting voltage regulator circuit, a resistor Rz and a light-emitting diode