Importance

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Abstract

In a relaxation oscillator where the oscillation frequency is proportional to the charge rate of a capacitor, independent current sources are connected through separate switches to change the charge rate of the capacitor and thus the oscillation frequency. Each switch is controlled by signals from a separate detector of a condition which requires that the oscillation frequency be changed. An oscillation frequency increase between the standby and alarm modes of a smoke detector is accomplished in one disclosed embodiment and duty cycle means for controlling the operative period of the alarm indicator during each cycle of the increased oscillator frequency is disclosed in a more particular embodiment.

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First Claim