Ring detector
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United States of America Patent
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Feb 14, 1989
Grant Date -
N/A
app pub date -
Feb 13, 1987
filing date -
Feb 13, 1987
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A device for detecting a specified signal on a conventional telephone line includes a pair of input terminals to which to connect a pair of conventional telephone lines, and a circuit connected to the input terminals that draws a different amount of power from a separate power source when the specified signal is present across the input terminals thant it draws otherwise. A transformer couples the power supply to the circuit while isolating the power source from the input terminals, and power sensing circuitry that senses a difference in power supplied to the transformer generates a control signal that is also isolated from the input terminals.
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