ELECTRONIC DIALLING KEYBOARD FOR TELEPHONE SETS WITH SENDING OF DECADIC PULSES INTERCHANGEABLE WITH THE CALLING DIAL

摘要

In order to enable the transmission of digital pulses under the control of a pushbutton-type call-number selector from a dial-equipped subscriber station, the output leads of a keyboard are connected on the one hand to a circulating memory, working into a pulse generator, and on the other hand to a timing network which responds to the depression of any pushbutton on the keyboard with emission of an enabling pulse making the memory receptive to the selected code combination. The timing network includes a delay network which briefly retards the enabling pulse to prevent the storage of spurious signals in response to transient energization of an output lead of the keyboard.