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公开(公告)号：US5164991A
公开(公告)日：1992-11-17
申请号：US479157
申请日：1990-02-13
IPC分类号： H03F1/56
CPC分类号： H03F1/56
摘要： An amplified speaker has an amplifier section including an audio amplifier powered from a power input section and a variable audio input section for supplying an input audio signal via an audio transformer to the audio amplifier. The power input section includes a rectifier bridge and a capacitor filter circuit, so that power may be obtained from an inexpensive unregulated AC source rather than an expensive regulated DC power supply. The variable audio input section permits audio signals at various levels from 30 mVrms to 70.7 Vrms to be inputted.
摘要翻译： 放大扬声器具有放大器部分，其包括由功率输入部分供电的音频放大器和可变音频输入部分，用于经由音频变压器将输入音频信号提供给音频放大器。 电源输入部分包括一个整流桥和一个电容滤波电路，从而可以从廉价的非调节交流电源获得功率，而不是昂贵的调节直流电源。 可变音频输入部分允许输入30 mVrms至70.7 Vrms的各种级别的音频信号。
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公开(公告)号：US5289534A
公开(公告)日：1994-02-22
申请号：US795374
申请日：1991-11-21
CPC分类号： H04M11/025
摘要： A door phone controller has a door ajar feature for alerting a user that a door was left open. The door phone controller accommodates the door ajar feature in several different ways depending upon how it is configured to interface with the central office line. If the door phone controller is configured to interface with the central office line as an individual station, then when a door is left open, the controller alerts the user via auxiliary alert contacts specifically provided for activating a customer chime. When the door phone controller is configured as a ring-down station, the door phone controller alerts the user that the door was left ajar by dialing a pre-programmed telephone number and sending a door ajar tone. If the door phone controller is configured as an interface with a trunk port, then when the door is left open, the controller alerts the user by ringing the trunk line and also energizing the auxiliary alert contacts. The user can both enable and disable the door ajar features via the telephone interface.
摘要翻译： 门电话控制器具有门用于警告用户门被打开的门开启功能。 门电话控制器根据其配置与中心局线路的连接方式，以几种不同的方式适应门的各种功能。 如果门电话控制器被配置为作为单独的站与中心局线路连接，则当门被打开时，控制器通过专门提供用于激活客户铃声的辅助警报联系人来向用户通知。 当门电话控制器被配置为下降站时，门电话控制器通过拨打预编程的电话号码并发送门前音来警告用户门已经开启。 如果门电话控制器被配置为与中继端口的接口，则当门被打开时，控制器通过振铃干线向用户通知并且给辅助警报联系人通电。 用户可以通过电话接口启用和禁用门前缀功能。
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公开(公告)号：US5315644A
公开(公告)日：1994-05-24
申请号：US795373
申请日：1991-11-21
CPC分类号： H04M11/02
摘要： A circuit for interfacing a host telephone system having a trunk line pair with a central office line pair and an additional circuit line pair includes a loop current monitor circuit for monitoring the host telephone system trunk line pair which is normally connected to the central office line pair. The loop current monitor provides a status signal output indicating the presence or absence of loop current. A relay controller receives the status signal and provides a relay control signal and a hold signal. A relay selectively connects the host telephone system trunk line pair to the additional circuit line pair in response to the relay control signal when loop current is detected after the host telephone goes off-hook. A hold termination circuit receives the hold signal and traps any loop current signals which may be detectable over the central office line pair. The relay controller circuit is active to generate the relay control signal only for an initial time period after the host telephone system goes off-hook.
摘要翻译： 用于将具有中心线对对的主干线对和附加电路线对的主机电话系统连接的电路包括用于监视通常连接到中心局线对上的主电话系统中继线对的回路电流监视电路 。 环路电流监视器提供指示环路电流存在或不存在的状态信号输出。 继电器控制器接收状态信号并提供继电器控制信号和保持信号。 当在主机摘机后检测到环路电流时，继电器响应于继电器控制信号，选择性地将主机电话系统中继线对与附加电路线对连接。 保持终端电路接收保持信号并捕获可能在中心局线路对上检测的任何环路电流信号。 继电器控制器电路仅在主机电话系统摘机之后的初始时间周期内才能产生继电器控制信号。
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