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随着我国通信事业的发展,国内各大中城市都已安装了直拨程控电话,这为国内的信息传递和各单位业务联系提供了方便。我们研制的一种成本低廉的装置(成本约为60元),可以自动切断未经允许的直拨电话和半自动长途电话(即173),而不影响正常市内电话的通信,以控制直拨电话的使用。当主人想要打直拨电话时,只需将开关一拨或将电子锁打开即可。该装置的电路简单,使用方便。一、基本原理大家知道,打电话拨号时,电话机将输出一串脉冲。拨号码“1”时,输出1个脉冲;拨号码“7”时,输出7个脉冲;除“0”比较特殊,它输出10个脉冲,其余的
With the development of China’s communications industry, all domestic major cities have installed direct-dial-program-controlled telephones, which provides convenience for the domestic information transmission and the business contacts of various units. A cost-effective device (at a cost of about $ 60) we developed that automatically cuts off unauthorized direct-dial and semi-automatic long distance calls (that is, 173) without affecting the normal local call traffic to control direct dialing use. When the owner wants to make a direct dialing call, simply dial the switch or open the electronic lock. The circuit of the device is simple and easy to use. First, the basic principle As we all know, call dialing, the phone will output a string of pulses. When the dialing number is “1”, one pulse will be output. When the dialing number “7”, seven pulses will be output. Except for “0”, it will output 10 pulses. The remaining