A ringing voltage trigger circuit
Номер патента: IES65388B2
Опубликовано: 18-10-1995
Автор(ы): Karl Pawley, Laoi Caoimhin O, Michael O'dwyer
Принадлежит: Lake Electronic Tech
Опубликовано: 18-10-1995
Автор(ы): Karl Pawley, Laoi Caoimhin O, Michael O'dwyer
Принадлежит: Lake Electronic Tech
Реферат: A trigger circuit for applying a voltage to a ring supply pin (2) of a speech chip (3) for activating a ringer (11) of a system phone in response to a ringing signal being applied to a telephone line (4) from a PBX. The trigger circuit (1) comprises first and second bridge rectifiers (8) and (9). The ring supply pin (2) is fed through a transistor (T1) from the second rectifier circuit (9). A smoothing capacitor (C4) biases the base of the transistor (T1) through a potential divider (R1,R2) for switching on the transistor (T1) on a ringing signal appearing on the telephone line (4). A voltage control circuit (12) provided between the transistor (T1) and the pin (2) which comprises a smoothing capacitor (C3) and a zener diode (ZD1) regulate and maintain the voltage being applied to the pin (2) at a level sufficient to hold the pin 2 on for so long as a ringing signal is being applied to the telephone line (4).
A ringing voltage trigger circuit
Номер патента: GB2299244B. Автор: Michael O'dwyer,Karl Pawley,Caoimhin O'laoi. Владелец: Lake Electronic Technologies Ltd. Дата публикации: 1999-04-21.