Telephone provided with an electromechanical transducer, method for adapting the frequency response of such a transducer and method for coding a melody

摘要

The telephone is provided with an electromechanical transducer includes a circuit for tuning the frequency response of the transducer, in order to obtain from the transducer a sound output at a constant sound level for a chosen frequency. Tuning is achieved by varying the cyclical ratio of the excitation signal applied to the transducer, such that the proportion of the 'on' and 'off' components of the signal varies within a given period. The application of different signals to the transducer generates output signals of different pitch, and these may be tuned to a melodic scale. When the telephone ringing sound is produced, the conventional bleep may be replaced by a specific melody.