The telephone-number-digital-display-circuit is designed, which picks up initially a signal from dial pulses with little effect on telephone and can finally display the successive dial numbers on LED display unit up to 10 digits. The dynamic display s...
The telephone-number-digital-display-circuit is designed, which picks up initially a signal from dial pulses with little effect on telephone and can finally display the successive dial numbers on LED display unit up to 10 digits. The dynamic display system and TTL IC were used to simplify wiring and the number of logic gates, and to improve the performance respectively.
This circuit was high reliable in the temperature range of 0°―70℃. It can be used to monitor dialing numbers to give confidence to subscribers, to test misconnecting troubles in telephone exchange offices, to inspect a complete dial set in a factories manufacturing the telephone set.