Multiple Alarm Tones From a Stepper Motor
Original Publication Date: 1985-Nov-01
Included in the Prior Art Database: 2005-Feb-19
It is known that a stepper motor may be used to produce an alarm signal. When overdriven at a sufficiently high frequency, the rotor, inhibited by inertia, remains stationary and vibrates, producing an audio frequency tone. The present embodiment observes that the frequency of the audio tone produced is directly related to input frequency. Thus, overdriving a stepper motor for successive discrete intervals at individually selected input frequencies, interspersed, as desired, with intervals of no input (silence), produces a distinctive multiple-tone alarm or "tune". Any number of different "tunes" are easily produced. Each "tune" indicates a different machine condition and, in a multiple machine environment, may also identify a specific machine.