Electronic alarm horn
Number of patents in Portfolio can not be more than 2000
United States of America Patent
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May 29, 1990
Grant Date -
N/A
app pub date -
Jan 27, 1989
filing date -
Jan 27, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
In an electronic horn for alarm systems of the type in which an alarm condition is indicated by a reversal of polarity in the d.c. power supply, an improvement provides a pair of terminals for connection to said d.c. power supply, a series circuit including a current limiting element and a capacitor connected across said terminals, a speaker operable to produce sound in response to current flow through the speaker, the speaker being constructed so that it will reverberate for a period after the current flow through the speaker has stopped and switch means for connecting the speaker in parallel to said capacitor for the discharge of energy stored in the capacitor through the speaker when the switch means is in its conductive state with means for continuously cycling the switch means between its conductive and non-conductive states at a predetermined frequency and for a predetermined duration of 'on' time for each switch cycle such that the sound produced by the pulses combines with that produced by reverberation of the speaker to provide a continuous tone as long as said pair of terminals is connected to the power source in the polarity indicative of an alarm condition.
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