电话机是电话通信网的终端设备,也是大众广泛使用的基本通信工具。为了加强对电话机的使用管理,我们采用MC14001B构成密码锁电路,在不影响正常市内通话的前提下,对电话机长途直拨及存入功能进行密码锁定,而主人能自由开启。下面对该电路作一介绍。 (一)工作原理直拨电话区域号首位数字规定为“0”,而一般市内电话号码首位数字为“非0”,根据这个特点,来设计密码锁电路。当键盘输入首位数字为“0”的数码时,拨号电路被锁住停止发号;输入首位数字为“非0”的数码时,拨号电路正常工作;拨号电路一旦被锁住,只有重新收一次钱(挂机一次),才能恢复拨号。在锁“0”状 Telephone is the terminal equipment of telephone communication network, it is also the basic communication tool that the public is extensively used. In order to strengthen the use of telephone management, we use the MC14001B password lock circuit, without affecting the normal city calls under the premise of telephone long-distance direct-dial and deposit function password lock, and the owner can freely open. The following describes the circuit. (A) Working principle The first digit of the direct dialing telephone area number is “0”, while the first digit of the general domestic telephone number is “non-zero”. According to this feature, the password lock circuit is designed. When the first digit of the keyboard is “0”, the dialing circuit is locked to stop sending numbers; when the first digit is “0”, the dialing circuit works normally; once the dialing circuit is locked, it can only be received again Money (hang up once) before resuming dialing. Locked in “0” shape