US3955102A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zero crossing detecting circuit
Assignee: Digital Equipment Corp
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Filing: 1975-04-21
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Granted: 1976-05-04
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Expires: 1995-04-21
Abstract
Abstract A zero-crossing detecting circuit where the input signal is applied to positive and negative threshold circuits. Each threshold circuit is connected to the input of a respective one-shot circuit which responds to the beginning edge of each output signal from its threshold circuit. The output pulses of both one-shots are applied to a NOR circuit which thereby responds to the beginning edges but not the trailing edges of the signals from the threshold circuits. Accordingly, variations in the trailing edges of the signals from the threshold circuits due to hysteresis or varying propogation times do not effect the circuit's output.
Inventors
- 👤 Chao S. Chi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:40
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/153; H03K5/1536
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
140 words
A circuit for indicating zero-crossings in an input signal comprising: first means for receiving said input signal and providing a signal when said input signal is above a predetermined positive threshold level; second means for receiving said input signal and providing a signal when said input signal is below a predetermined negative threshold, equal to said positive threshold; a pair of one-shot circuits respectively connected to said first and second means, each one-shot circuit being adapted to become placed in the active state in response to the beginning of the signal from its respective first or second means; and an output gating circuit connected to each one-shot circuit and adapted to provide a signal in response to either one-shot circuit becoming placed in an active state, each response of said output gating circuit indicating a zero-crossing in the input signal.
Claim 2
Dependent Claim
140 words
A circuit for indicating zero-crossings in an input signal comprising: first means for receiving said input signal and providing a signal when said input signal is above a predetermined positive threshold level; second means for receiving said input signal and providing a signal when said input signal is below a predetermined negative threshold, equal to said positive threshold; a pair of one-shot circuits respectively connected to said first and second means, each one-shot circuit being adapted to become placed in the active state in response to the beginning of the signal from its respective first or second means; and an output gating circuit connected to each one-shot circuit and adapted to provide a signal in response to either one-shot circuit becoming placed in an active state, each response of said output gating circuit indicating a zero-crossing in the input signal.
Claim 3
Dependent Claim
15 words
The circuit as recited in claim 1 wherein said input signal is an analog voltage.
Claim 4
Dependent Claim
26 words
The circuit as recited in claim 1 wherein said first and second receiving means are a pair of analog comparators fabricated on a single integrated chip.
Claim 5
Dependent Claim
16 words
The circuit as recited in claim 1 wherein said output gating circuit is a NOR gate.
Claim 6
Dependent Claim
26 words
The circuit is recited in claim 1 wherein said first and second means possess inherent characteristics which cause variations in the ends of their respective signals.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-04 | 1979-11-03 | 1980-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-04 | 1983-11-03 | 1984-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-04 | 1987-11-03 | 1988-05-04 | $7700.00 | Window Closed / Lapsed |