US3684172A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermocouple temperature control system
Assignee: Individual
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Filing: 1970-10-08
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Granted: 1972-08-15
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Expires: 1990-10-08
Abstract
Abstract The present system provides a circuit wherein a direct-current amplified difference signals is produced in response to an extremely small difference signal being developed by comparing the small voltage developed across a thermocouple, (acting as a temperature sensor) aNd a selectable variable voltage representing the desired temperature of the location being monitored. The amplified direct-current difference voltage is attenuated and fed back to an operational amplifier to develop a stable difference signal input thereto. In addition, the amplified direct-current difference voltage is applied to the control element of a switching circuit. The switching circuit has a pulsating direct-current signal applied to the input-output elements and switches to turn on the heating means in response to the value of the applied difference signal (which is applied to the control element) exceeding a predetermined percentage of the value of the applied pulsating direct-current signal.
Inventors
- 👤 Egils Evalds
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:42
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/22; G05D23/1927
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
151 words
A thermocouple temperature control system comprising in combination: a voltage source; a voltage divider network coupled to said voltage source; a voltage comparison circuit connected to said voltage divider network to provide at a first terminal a voltage signal having a first polarity; a thermocouple connected to said first terminal so that the voltage generated by said thermocouple acts in opposition to said voltage signal having said first polarity thereby producing a difference signal at a first terminal of said thermocouple; signal amplifier means connected to said first terminal of said thermocouple to receive said difference signal and in response thereto to provide an amplified output signal; switching means connected to said amplifier means to receive said amplified output signal, said switching means formed to switch in response to said output signals; and heating means connected to said switching means to produce heat in response to said switching means being switched.
Claim 2
Dependent Claim
151 words
A thermocouple temperature control system comprising in combination: a voltage source; a voltage divider network coupled to said voltage source; a voltage comparison circuit connected to said voltage divider network to provide at a first terminal a voltage signal having a first polarity; a thermocouple connected to said first terminal so that the voltage generated by said thermocouple acts in opposition to said voltage signal having said first polarity thereby producing a difference signal at a first terminal of said thermocouple; signal amplifier means connected to said first terminal of said thermocouple to receive said difference signal and in response thereto to provide an amplified output signal; switching means connected to said amplifier means to receive said amplified output signal, said switching means formed to switch in response to said output signals; and heating means connected to said switching means to produce heat in response to said switching means being switched.
Claim 3
Dependent Claim
30 words
A thermocouple temperature control system according to claim 1 wherein said voltage divider network includes resistors therein which provide said voltage signal at said first terminal in the milli-volt range.
Claim 4
Dependent Claim
66 words
A thermocouple temperature control system aCcording to claim 1 wherein said amplifier means includes an operational amplifier having an output terminal, first and second input signal means and first and second bias means and wherein said first input signal means is coupled to said first terminal of said thermocouple and wherein there is a feedback network connecting said output terminal to said second input signal means.
Claim 5
Dependent Claim
43 words
A thermocouple temperature control system according to claim 3 wherein said switching means includes a unijunction transistor having an input element, an output element and a control element and wherein said control element is connected to said output terminal of said operational amplifier.
Claim 6
Dependent Claim
131 words
A thermocouple temperature control system according to claim 4 wherein said switching means includes a pulse transformer having a primary winding and a secondary winding, a capacitor connected between one terminal of the primary winding of said pulse transformer and said control element, circuitry means connecting the other terminal of the primary winding of said pulse transformer to the output element of said unijunction transistor and wherein said switching means includes an electronic switching means connected across the secondary winding of said pulse transformer so that when said capacitor is charged to a predetermined value said unijunction transistor conducts thereby discharging said capacitor while simultaneously inducing a voltage in said secondary winding to fire said electronic switching means and further wherein the heating means is connected to said electronic switching means.
Claim 7
Dependent Claim
88 words
A thermocouple temperature control system according to claim 3 wherein the said first and second bias means of said operational amplifier are connected to said power source across first and second series connected Zener diodes and wherein the center point of said serially connected Zener diodes is connected to ground so that one bias means of said operational amplifier is connected to a voltage higher than ground and wherein said bias means of said operational transformer is connected to a voltage input whose value is less then ground.
Claim 8
Dependent Claim
88 words
A thermocouple temperature control system according to claim 1 wherein there is further included a compensating voltage divider network connected to said first voltage divider network wherein there is further included a temperature responsive device disposed in close proximity to said thermocouple and connected to said temperature compensating voltage divider network such that the voltage at said first terminal varies in accordance with the voltage across said temperature responsive device thereby causing the voltage at said first terminal to be responsive to the temperature condition of said thermocouple.
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) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |