| 摘要 |
PURPOSE:To make it that a frequency against the subscriber's request can be easily changed, by installing an oscillator to oscillate a specific frequency, a counting circuit to count a fundamental frequency, a storage circuit to designate the output of this counting circuit as address information, a bit selection circuit and a conversion means to convert this bit signal to an AC signal. CONSTITUTION:Making the certain specific frequency oscillated from a fundamental frequency oscillator 10 as fundamental frequency the counting circuit 11 performs the counting of 0-(n). Then, its information counted is considered as address information 12, and the data stored against the respective addresses are successively outputted. On the one hand, the pushbutton information generated by the subscriber's operation is converted to the bit selection information, fed to a bit selection circuit 15 as control signal, and the bit information of frequency designated on the basis of its control signal is outputted, however, since this signal is a square lar pulse, it is converted from a square wave to a sine wave by a filter 16, and made normal as sound. Further, in a mixing circuit 17, the respective frequencies are mixed, become the multi-frequencies, and transmitted. |
