Patent US3944935A successfully refreshed from Google Patents.
US3944935A
Expired / Lapsed
US
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Apparatus for generating a d.c. signal proportional to an input frequency
Assignee: ZF International UK Ltd
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Filing: 1974-11-26
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Granted: 1976-03-16
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Expires: 1994-11-26
Abstract
Abstract An apparatus for generating a d.c. output signal which is proportional to the frequency of an alternating input signal, includes a pulse generator and a counter arranged to count pulses from the generator for a time which is dependent on the input signal frequency. A digital to analog converter is responsive to the count in the counter and also to the d.c. output signal to provide an intermediate d.c. signal which is compared with a d.c. reference signal. The difference between the intermediate and reference signals is integrated to provide the output signal. The arrangement is such that the d.c. output signal is directly proportional to the input signal frequency.
Inventors
- 👤 Anthony Brian Plant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:08
CPC Classifications
H; H03; H03K; H03K9/00; H03K9/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
181 words
An apparatus for generating a d.c. output signal whose magnitude is proportional to the frequency of an electrical input signal, comprising means for generating a train of substantially equispaced electrical pulses, a pulse counter, gating means responsive to said input signal for gating said pulses to said counter for a time interval which is dependent on the frequency of said input signal, a digital to analog converter for providing a d.c. signal dependent on the count in said counter at the end of said time interval, a summing junction responsive to said d.c. signal and to an electrical reference signal to generate a control signal proportional to the difference between said d.c. signal and said reference signal, and an integrating circuit responsive to said control signal to generate said output signal, said digital to analog converter also being responsive to said output signal so that said d.c. signal is proportional to the product of said count and said output signal, and a feedback arrangement provided such that variations in said d.c. signal are opposed by corresponding changes in said output signal.
Claim 2
Independent Claim
181 words
An apparatus for generating a d.c. output signal whose magnitude is proportional to the frequency of an electrical input signal, comprising means for generating a train of substantially equispaced electrical pulses, a pulse counter, gating means responsive to said input signal for gating said pulses to said counter for a time interval which is dependent on the frequency of said input signal, a digital to analog converter for providing a d.c. signal dependent on the count in said counter at the end of said time interval, a summing junction responsive to said d.c. signal and to an electrical reference signal to generate a control signal proportional to the difference between said d.c. signal and said reference signal, and an integrating circuit responsive to said control signal to generate said output signal, said digital to analog converter also being responsive to said output signal so that said d.c. signal is proportional to the product of said count and said output signal, and a feedback arrangement provided such that variations in said d.c. signal are opposed by corresponding changes in said output signal.
Claim 3
Dependent Claim
65 words
An apparatus as claimed in claim 1 in which said means responsive to the input signal comprises means for generating a sequence of shaped pulses having a frequency dependent to the input frequency, and a gate circuit, responsive to said shaped pulses, for applying said train of pulses to said counter, said time interval being equal to the duration of one of said shaped pulses.
Claim 4
Dependent Claim
26 words
An apparatus as claimed in claim 2 in which each said shaped pulse has a duration substantially equal to one half cycle of said input signal.
Claim 5
Dependent Claim
52 words
An apparatus as claimed in claim 2 which includes a register adapted to receive the count in said counter, and means, responsive to said shaped pulses, for loadin said count into said register at the end of one of said time intervals, and for subsequently setting said count to a predetermined value.
Claim 6
Dependent Claim
94 words
An apparatus as claimed in claim 2 which includes a plurality of means for generating sequences of shaped pulses having frequencies dependent on respective ones of a plurality of input signals, in which said gate circuit comprises means, sequentially responsive to shaped pulses from respective ones of said plurality of pulse-generating means, for applying said train of pulses to said counter, and which includes a plurality of sample and hold devices, and means for sequentially operating said sample and hold devices to store respective output signals corresponding to respective one of said input signals.
Claim 7
Dependent Claim
21 words
An apparatus as claimed in claim 5 which includes means for selecting said reference voltage from a plurality of input voltages.
Claim 8
Dependent Claim
21 words
An apparatus as claimed in claim 1 which includes means for selecting said reference voltage from a plurality of input voltages.
Claim 9
Dependent Claim
23 words
An apparatus as claimed in claim 1 in which said pulse-train generating means includes means for varying the frequency of said pulse train.
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) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |