Patent US1926587A successfully refreshed from Google Patents.
US3854089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low voltage monitor circuit
Assignee: Telent Technologies Services Ltd
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Filing: 1974-01-14
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Granted: 1974-12-10
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Expires: 1994-01-14
Abstract
Abstract A simple and inexpensive circuit for monitoring one or more current sources and producing an active output signal whenever one of the monitored sources fails. Current from the monitored sources is applied to respective transistors to hold them in saturation so long as the sources operate normally. The transistors are connected in series with each other and with the input of an optical coupling device. An annunciator device is connected in series with a control transistor across a current source that is independent of the monitored sources, and the output of the optical coupling device holds the control transistor cut off so long as the monitored sources remain normally operative. When one of the monitored sources fails, or suffers a significant voltage drop, current applied at the input of the coupling device is reduced causing the control transistor to conduct, thereby to energize the annunciator.
Inventors
- 👤 M Emler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:04
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/22; G01R19/00; G01R19/145; G01R19/155
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
111 words
A monitoring circuit for monitoring the voltage across a dc. current source comprising a sensing transistor, means for connecting the base and emitter electrodes of said transistor to respective terminals of the source to be monitored, an optical coupling device having an input diode connected in series with the collector and emitter of said transistor across the source to be monitored, a control transistor having its input connected to the output of said optical coupling device, an annunciator connected in series with the collector and emitter of said control transistor, and means for connecting said annunciator and said control transistor across a current source independent of the source to be monitored.
Claim 2
Dependent Claim
111 words
A monitoring circuit for monitoring the voltage across a dc. current source comprising a sensing transistor, means for connecting the base and emitter electrodes of said transistor to respective terminals of the source to be monitored, an optical coupling device having an input diode connected in series with the collector and emitter of said transistor across the source to be monitored, a control transistor having its input connected to the output of said optical coupling device, an annunciator connected in series with the collector and emitter of said control transistor, and means for connecting said annunciator and said control transistor across a current source independent of the source to be monitored.
Claim 3
Dependent Claim
186 words
A circuit for monitoring a plurality of dc. current sources and for producing an active output signal in response to a predetermined drop in the voltage across any one of the sources comprising sensing transistors, one for each of the sources to be monitored, means for connecting the base and emitter of each of said transistors across a respective one of the sources, Zener diodes equal in number to the sources, means connecting said diodes respectively in series between the sources and the bases of said transistors, an optical coupling device having a diode at its input, means connecting said diode of said coupling device in series with the collectors and emitters of all of said transistors across one of the sources to be monitored, an annunciator device, a control transistor, the input of said control transistor being connected to the output of said optical coupling device, means connecting said annunciator device in series with said control transistor, and means for energizing the output of said optical coupling device, said annunciator, and said control transistor from a current source independent of the sources to be monitored.
Claim 4
Dependent Claim
186 words
A circuit for monitoring a plurality of dc. current sources and for producing an active output signal in response to a predetermined drop in the voltage across any one of the sources comprising sensing transistors, one for each of the sources to be monitored, means for connecting the base and emitter of each of said transistors across a respective one of the sources, Zener diodes equal in number to the sources, means connecting said diodes respectively in series between the sources and the bases of said transistors, an optical coupling device having a diode at its input, means connecting said diode of said coupling device in series with the collectors and emitters of all of said transistors across one of the sources to be monitored, an annunciator device, a control transistor, the input of said control transistor being connected to the output of said optical coupling device, means connecting said annunciator device in series with said control transistor, and means for energizing the output of said optical coupling device, said annunciator, and said control transistor from a current source independent of the sources to be monitored.
Claim 5
Dependent Claim
39 words
A circuit according to claim 2 including an amplifier connected between the output of said optical coupling device and said control transistor to cause the annunciator to respond to small changes in the voltages of the sources being monitored.
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) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |