US3757195A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isolated two wire signal transmitter
Assignee: Honeywell Inc
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Filing: 1972-08-11
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Granted: 1973-09-04
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Expires: 1992-08-11
Abstract
Abstract There is disclosed a process variable signal transmitter system which features a two-wire transmission line yet provides conductive isolation between the transmitter, the power source and the utilization device. The transmitter is powered from a power supply link which is transformer coupled to the power source. The power supply link includes a current transformer to couple a modulated data signal to an output circuit.
Inventors
- 👤 M Sklaroof
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:20
CPC Classifications
G; G08; G08C; G08C19/00; G08C19/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
173 words
An isolator means for a signal transducer/transmitter system wherein a transducer/transmitter is connected to a control station by a two-wire transmission line and wherein all of the energizing current for said transducer/transmitter as well as the intelligence signals from said transducer/transmitter is carried by said two-wire transmission line, said isolator means comprising: a power transformer having a primary winding suitable for connection to an AC energy source and a secondary winding connected in an energizing circuit for said transducer/transmitter; said energizing circuit including a current rectifying means for converting AC energy from said power transformer to DC energy for said transducer/transmitter thereby defining an AC portion and a DC portion of said energizing circuit; a current transformer having a primary winding serially connected in said AC portion of said energizing circuit; a signal translation circuit including an operational amplifier and output circuit means for connection to a utilization device; a secondary winding on said current transformer, and demodulator means connected between said last mentioned secondary winding and the input of said operational amplifier.
Claim 2
Dependent Claim
173 words
An isolator means for a signal transducer/transmitter system wherein a transducer/transmitter is connected to a control station by a two-wire transmission line and wherein all of the energizing current for said transducer/transmitter as well as the intelligence signals from said transducer/transmitter is carried by said two-wire transmission line, said isolator means comprising: a power transformer having a primary winding suitable for connection to an AC energy source and a secondary winding connected in an energizing circuit for said transducer/transmitter; said energizing circuit including a current rectifying means for converting AC energy from said power transformer to DC energy for said transducer/transmitter thereby defining an AC portion and a DC portion of said energizing circuit; a current transformer having a primary winding serially connected in said AC portion of said energizing circuit; a signal translation circuit including an operational amplifier and output circuit means for connection to a utilization device; a secondary winding on said current transformer, and demodulator means connected between said last mentioned secondary winding and the input of said operational amplifier.
Claim 3
Dependent Claim
15 words
The invention set forth in claim 1 wherein said demodulator means includes a synchronous demodulator.
Claim 4
Dependent Claim
62 words
The invention set forth in claim 2 wherein said synchronous demodulator includes a first field effect transistor serially connected between said secondary winding of said current transformer and an input terminal of said operational amplifier, a seocnd field effect transistor connected in shunt across the terminals of said last mentioned secondary winding, and means for rendering said field effect transistors alternately conductive.
Claim 5
Dependent Claim
15 words
Theinvention set forth in claim 1 wherein said demodulator means includes a passive rectification means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |