System for controlling an electronic warning device
AssigneeSaft-Societe des Accumulateurs Fixes et de Traction
InventorsDaniel Lelaidier, Pierre Godard
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Abstract
The invention relates to electronic warning devices. The control system includes means for supplying an accurate clock signal and a divider (CD1, CD2) for dividing the clock signal to obtain an audio frequency, adjusting the mark/space ratio of the audio frequency for application to a power transistor (T6), said transistor driving a loudspeaker (HP), providing a cyclic modulation for modulating the clock frequency; and timing the duration of the sound emission of the loud speaker. The timing functions can all be provided without the use of electrolytic capacitors as would otherwise have been necessary, thereby avoiding problems due to the lack of precision and drift in the values of such capacitors.
Claims7
A system for generating an audible warning signal, the system comprising:
- a loudspeaker;
- a power transistor connected for driving the loudspeaker;
- a single time base oscillator having an output for providing a clock signal at a frequency which is variable over a predetermined range of frequencies and an input for a command signal for varying said output frequency;
- and
- a divider having an input connected to the output of the single time base oscillator to divide the clock signal and a plurality of outputs for producing predetermined integral submultiples of the output frequency from said single time base oscillator, said plurality of outputs including
- a first output whereat the oscillator frequency has been divided by a first predetermined integral number of times to produce an audio signal at an audio frequency;
- a second output whereat the time base oscillator frequency has been divided a second predetermined integral number of times to produce a signal for adjusting the mark/space ratio of the audio signal;
- gating means having a first input coupled to the first output of the divider, a second input coupled to the second output of the divider and an output coupled to the power transistor, said adjusting signal being gated with the audio signal by said gating means to adjust the mark/space ratio of the audio signal, and the adjusted audio signal being applied to the power transistor;
- a third output whereat the time base oscillator frequency has been divided a third predetermined integral number of times, greater than said first integral number, to produce a cyclic modulation signal at a frequency lower than the audio signal, said third output of the divider being coupled to the input of the time base oscillator to vary the frequency of the clock signal;
- and
- a fourth output whereat the time base oscillator frequency has been divided a fourth predetermined integral number of times, greater than said third integral number, to produce a timing signal to turn off the audible warning signal after it has sounded for a predetermined period.
Dependencies are inferred from the claim text.