| 摘要 |
<p>1. Frequency generator for generating signalling frequencies in a multifrequency telephone apparatus comprising a quartz oscillator (1) ; a first frequency divider (2) which is connected to the quartz oscillator (1) and has a fixed divisor ; a frequency divider (3, 4) which is connected to the first frequency divider (2) and has an integral divisor which can be set by a programming network (7) for generating frequencies selected through the programming network (7) ; and a digital/analog converter comprising a fourth frequency divider (5) with a fixed divisor, and a weight network (6) connected to the steps of the fourth frequency divider (5) for forming step-shaped signals of approximate sine wavefrom ; characterized in that the frequency divider (3, 4) with a settable integral divisor comprises and AND member (37) and an auxiliary flip-flop (4) as last step ; in that the output of the flip-flop (4h via 43h) is connected to a first input of the AND member (37) ; in that at least one further input of the AND member (37) is connected to the output of a divider step (31, 32) preceding the auxiliary flip-flop (4h) ; and in that the output of the AND member (37 via 341) is connected to the reset input of the auxiliary flip-flop (4h), and, controlled by the programming network (7 via 731, 732, 741, ..., 74p), to the set or reset input of at least one divider step (31, 32, 41, ..., 4p) preceding the auxiliary flip-flop (4h).</p> |
