| 摘要 |
PURPOSE:To enable to install a push button PB dial conversion circuit to a rotating dial type telephone set, by keeping an output for a prescribed time on an output line of a gate circuit corresponding to the number of dials, when a series of dial pulse is finished. CONSTITUTION:The off-hooking of a telephone set Tel is detected with a photo coupler PC, and a JK flip-flop FF1. When dialing is made at a telephone set Tel, one-shot multivibrator MM1 is started with the 1st dial pulse, and an output is made for a prescribed time covering a series of dial pulse and the off- hooking of the telephone set Tel is displayed. The number of interruption of a dial is counted with a count circuit COUNT via a one-shot multivibrator MM3, the result is decoded at a decoder DEC and outputted on output lines l1-l10 of a gate circuit G coresponding to the number of dials. |
