US3742379A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Voltage to frequency converter
Assignee: Johnson Service Co
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Filing: 1970-11-12
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Granted: 1973-06-26
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Expires: 1990-11-12
Abstract
Abstract An operational amplifier having a feedback circuit produces a periodic signal having a frequency linearly proportional to the magnitude of an analog input voltage. The feedback circuit includes three parallel paths, one of which includes a resistor in series with a zener diode, the second of which includes a controlled rectifier having a gate connected to the junction of the resistor and diode and the third of which includes a capacitor. The capacitor charges to the Zener breakdown voltage which then conducts and biases the controlled rectifier into conduction to discharge the capacitor. An output circuit is connected to the capacitor to receive the discharge pulses, which are converted into a square wave signal by a Schmitt trigger circuit. The analog input voltage is amplified by a differential amplifying section.
Inventors
- 👤 Lean M Mc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:26
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/50; H03K4/56; H03K7/00; H03K7/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
196 words
A circuit to produce a periodic signal having a frequency linearly proportional to the magnitude of an analog input signal, comprising a capacitor, a constant current source including An amplifying means having an input means to receive said analog signal and defining a source of constant current, said capacitor being connected in a feedback loop between the output and input means of said amplifying means to charge said capacitor in accordance with the magnitude of the input signal, an inductor connected in series with said capacitor in said feedback loop, a unidirectional gated switch means having a holding current of essentially zero and having an essentially zero impedance when turned on, said gated switch means being connected in parallel with the capacitor and the inductive means, a voltage sensing branch including a voltage breakdown element in series with a current limit means connected directly in parallel with said capacitor and said inductor and in parallel with said gated switch means and defining a precise trigger voltage signal at a selected capacitor voltage, the junction of said voltage breakdown element and the current limit means being connected to impress the voltage signal on said gated switch means.
Claim 2
Dependent Claim
196 words
A circuit to produce a periodic signal having a frequency linearly proportional to the magnitude of an analog input signal, comprising a capacitor, a constant current source including An amplifying means having an input means to receive said analog signal and defining a source of constant current, said capacitor being connected in a feedback loop between the output and input means of said amplifying means to charge said capacitor in accordance with the magnitude of the input signal, an inductor connected in series with said capacitor in said feedback loop, a unidirectional gated switch means having a holding current of essentially zero and having an essentially zero impedance when turned on, said gated switch means being connected in parallel with the capacitor and the inductive means, a voltage sensing branch including a voltage breakdown element in series with a current limit means connected directly in parallel with said capacitor and said inductor and in parallel with said gated switch means and defining a precise trigger voltage signal at a selected capacitor voltage, the junction of said voltage breakdown element and the current limit means being connected to impress the voltage signal on said gated switch means.
Claim 3
Dependent Claim
15 words
The circuit of claim 1, wherein said gated switch means is a controlled rectifier means.
Claim 4
Dependent Claim
44 words
The circuit of claim 2, wherein said voltage breakdown element is a serially Zener diode and said current limit means is a resistor, said Zener diode conducting when said capacitor charges to said selected voltage level to initiate conduction in said gated switch means.
Claim 5
Dependent Claim
33 words
The circuit of claim 1 including a differential amplifier means having a set point signal means input and an analog signal means input and having an output means connected to said amplifying means.
Claim 6
Dependent Claim
54 words
The circuit of claim 1 having a square wave generator circuit connected to said feedback circuit between the capacitor and the input means to receive said periodic signal and producing a square wave signal having a frequency one-half of the frequency of said periodic signal and proportional to the magnitude of said analog signal.
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) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |