US3755688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for supervising circuits
Assignee: US Philips Corp
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Filing: 1971-12-03
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Granted: 1973-08-28
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Expires: 1991-12-03
Abstract
Abstract Apparatus for monitoring thermocouples comprises a Wien Bridge Oscillator with the thermocouple connected as a part of the bridge. The oscillator parameters are chosen so that oscillations do not occur during normal operation of the thermocouple. The frequency of oscillations are determined by an RC-network. An indicating device is controlled by the output voltage of the oscillator.
Inventors
- 👤 A Hohler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:37
CPC Classifications
H; H02; H02H; H02H5/00; H02H5/10; G; G01; G01K; G01K7/00; G01K7/02; G01K7/026
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
111 words
Apparatus for monitoring an electric element comprising, an amplifier, a plurality of resistors and capacitors, means connecting said resistors and capacitors in an RC network and in circuit with said element and said amplifier to form a Wien Bridge Oscillator which is arranged so as not to oscillate during normal operation of the electric element, said RC network determining the frequency of oscillation and the start of oscillation being determined by a change in the resistance value of said electric element when a defect occurs therein, and an indicating device controlled by the output voltage of the oscIllator so as to indicate the occurrence of a defect in said electric element.
Claim 2
Dependent Claim
111 words
Apparatus for monitoring an electric element comprising, an amplifier, a plurality of resistors and capacitors, means connecting said resistors and capacitors in an RC network and in circuit with said element and said amplifier to form a Wien Bridge Oscillator which is arranged so as not to oscillate during normal operation of the electric element, said RC network determining the frequency of oscillation and the start of oscillation being determined by a change in the resistance value of said electric element when a defect occurs therein, and an indicating device controlled by the output voltage of the oscIllator so as to indicate the occurrence of a defect in said electric element.
Claim 3
Dependent Claim
38 words
Apparatus as claimed in claim 1 wherein the resistors and capacitors of said RC network are chosen as to produce a frequency of oscillation of about 16 KHz upon the occurrence of a fault in said electric element.
Claim 4
Dependent Claim
19 words
Apparatus as claimed in claim 1 further comprising circuit means for providing an adjustable negative feedback for said amplifier.
Claim 5
Dependent Claim
30 words
Apparatus as claimed in claim 1 wherein said indicating device comprises a recording instrument connected in parallel with the input terminals of the amplifier and having a high input impedance.
Claim 6
Dependent Claim
42 words
Apparatus as claimed in claim 1 wherein said RC network includes a first branch of the bridge having a capacitor and resistance means connected in parallel to the input terminals of the amplifier, and wherein the resistance means includes said electric element.
Claim 7
Dependent Claim
40 words
Apparatus as claimed in claim 5 wherein said RC network further comprises a second branch of the bridge that includes a resistor and a second capacitor connected in series between an output terminal and an input terminal of the amplifier.
Claim 8
Dependent Claim
44 words
Apparatus as claimed in claim 6 wherein the input terminals of the indicating device are connected to the input terminals of the amplifier, and means providing a feedback path between an output terminal of the amplifier and an input terminal of the indicating device.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |