Abstract: Apparatus is disclosed which is employed to provide an audible sound at a given repetition rate to enable one to test and calibrate a timing mechanism such as a watch which employs a non-audible frequency source, such as a crystal or quartz oscillator. The apparatus employs a pickup antenna and tuned circuit means which are responsive to the frequency radiated by the oscillator employed in the horological device to be tested. This frequency is processed by means of suitable circuitry to provide an output frequency within the audible range and of a repetition rate consistent with the repetition rate of a prior art mechanical horological device. The output frequency signal is applied to an audio transducer to thus provide an audible signal which is synchronized to the crystal oscillator signal to thereby enable a user to employ a prior art calibration instrument for testing and calibration of the above noted devices.