US3573780A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic telephone alarm system
Assignee: Individual
•
Filing: 1968-09-27
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Granted: 1971-04-06
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Expires: 1988-09-27
Abstract
Abstract An alarm actuating circuit is disclosed for monitoring the condition of a communication line. As long as a line potential exists, an amplifier is cut off. In the case of a short circuit, open fault on the line or grounding of the battery side of the input to the communication line, the cut off no longer exists and the amplifier closes a relay to sound an alarm. The line current required is so small as to be negligible.
Inventors
- 👤 Franklin C Butterbaugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:38
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
120 words
An alarm circuit system for signalling attenuation of a potential between communications lines, comprising: amplifier means adapted for biased cutoff by said potential between the communications lines and connected to the said lines for receiving cutoff bias by the said potential therebetween, said amplifier means including a solid-state device and a low-pass high impedance phase-changing circuit bridging said communications lines, alarm means responsive to the said amplifier means, and power supply means connected to all said amplifier and alarm means, whereby attenuation of the potential between the said communications lines terminates the amplifier cutoff bias causing the amplifier to become actuated by the power supply and to operate the said responsive alarm means thereby signalling said attenuation of the potential.
Claim 2
Dependent Claim
120 words
An alarm circuit system for signalling attenuation of a potential between communications lines, comprising: amplifier means adapted for biased cutoff by said potential between the communications lines and connected to the said lines for receiving cutoff bias by the said potential therebetween, said amplifier means including a solid-state device and a low-pass high impedance phase-changing circuit bridging said communications lines, alarm means responsive to the said amplifier means, and power supply means connected to all said amplifier and alarm means, whereby attenuation of the potential between the said communications lines terminates the amplifier cutoff bias causing the amplifier to become actuated by the power supply and to operate the said responsive alarm means thereby signalling said attenuation of the potential.
Claim 3
Dependent Claim
31 words
An alarm circuit system as recited in claim 1, and additionally a test switch adapted to reverse the polarity of said bridging of the amplifier means circuit across the communications lines.
Claim 4
Dependent Claim
86 words
An alarm circuit system as recited in claim 2, wherein said alarm means includes a normally-open contact relay energized to close the contact by output of the amplifier means on termination of the said cutoff bias, an oscillator circuit adapted for connection to the power supply through a contact of the said responsive relay on termination of the cutoff bias, and a radio speaker in the oscillator circuit responsive to oscillations thereof on said connection with the power supply, for signalling attenuation of the said potential.
Claim 5
Dependent Claim
31 words
An alarm circuit system as recited in claim 3, wherein said power supply includes an isolation transformer, a battery, and a rectifier circuit including a filter between said transformer and battery.
References Cited (Backward Citations)
US3320473A
Cited
US3392379A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |