Patent US3821562A successfully refreshed from Google Patents.
US3821562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermocouple amplifier
Assignee: Motors Liquidation Co
•
Filing: 1973-07-20
•
Granted: 1974-06-28
•
Expires: 1993-07-20
Abstract
Abstract A thermocouple system includes an operational amplifier connecting a thermocouple to an output line with arrangements to provide an abnormally low output when there is a ground or short in the thermocouple or its leads. The positive thermocouple lead is connected to a point between a controlled voltage positive supply and ground of a voltage divider network including a cold junction compensator. The negative lead of the thermocouple is connected to the controlled positive line through a resistor and to the normal inverting input of the operational amplifier. If the thermocouple circuit opens, the normal drop through the voltage divider is lost and the amplifier input goes to a high voltage level and the output to a low level. The operational amplifier output may be overridden by a switching transistor which is normally held turned off by a normally conducting first stage transistor. The first stage transistor is of the NPN type with emitter grounded and collector connected through a resistor to the positive supply. The base of this transistor is connected to a point in the thermocouple voltage divider circuit between the thermocouple and ground so that grounding of the positive thermocouple lead turns it off. The base of this transistor is also connected through a diode to the negative thermocouple lead, the diode having a lower voltage drop than the base-emitter circuit of the transistor, so that grounding the negative thermocouple lead also turns it off.
Inventors
- 👤 J Davis
- 👤 E Lopke
- 👤 L Pechous
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:05
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/22; G01; G01K; G01K7/00; G01K7/02; G01K7/026
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
144 words
A temperature-responsive system comprising a thermocouple; a power input connectable to a constant-voltage source; voltagedivider means connected to the power input establishing a datum potential for one terminal of the thermocouple; an amplifier having an input connected to the other terminal of the thermocouple and providing an output varying with thermocouple emf; switching means connected to the amplifier effective when operative to provide an extreme limit output signal; the switching means including a control electrode responsive to voltage shift past a predetermined threshold to put the switching means in operative condition; and means connecting the control electrode to the voltage-divider means and through unidirectional conducting means to the said other terminal of the thermocouple, so that a ground on either thermocouple terminal shifts the voltage on the control electrode to cause the switching means to become operative to provide the extreme limit output signal.
Claim 2
Dependent Claim
144 words
A temperature-responsive system comprising a thermocouple; a power input connectable to a constant-voltage source; voltagedivider means connected to the power input establishing a datum potential for one terminal of the thermocouple; an amplifier having an input connected to the other terminal of the thermocouple and providing an output varying with thermocouple emf; switching means connected to the amplifier effective when operative to provide an extreme limit output signal; the switching means including a control electrode responsive to voltage shift past a predetermined threshold to put the switching means in operative condition; and means connecting the control electrode to the voltage-divider means and through unidirectional conducting means to the said other terminal of the thermocouple, so that a ground on either thermocouple terminal shifts the voltage on the control electrode to cause the switching means to become operative to provide the extreme limit output signal.
Claim 3
Dependent Claim
172 words
A temperature-responsive system comprising a thermocouple; a power input connectable to a constantvoltage source; voltage-divider means connected to the power input establishing a datum potential for one terminal of the thermocouple; an amplifier having an input connected to the other terminal of the thermocouple and providing an output varying with thermocouple emf; a high-resistance connection from the amplifier input to the power input effective when the thermocouple circuit is opened to cause the amplifier to provide an extreme limit signal; switching means connected to the amplifier output and effective to override the amplifier output and provide an extreme limit signal when operative; the switching means including a control electrode responsive to voltage shift past a predetermined threshold to put the switching means in operative condition; and means connecting the control electrode to the voltage-divider means and through unidirectional conducting means to the said other terminal of the thermocouple, so that a ground on either thermocouple terminal shifts the voltage on the control electrode to cause the switching means to override the amplifier.
Claim 4
Dependent Claim
172 words
A temperature-responsive system comprising a thermocouple; a power input connectable to a constantvoltage source; voltage-divider means connected to the power input establishing a datum potential for one terminal of the thermocouple; an amplifier having an input connected to the other terminal of the thermocouple and providing an output varying with thermocouple emf; a high-resistance connection from the amplifier input to the power input effective when the thermocouple circuit is opened to cause the amplifier to provide an extreme limit signal; switching means connected to the amplifier output and effective to override the amplifier output and provide an extreme limit signal when operative; the switching means including a control electrode responsive to voltage shift past a predetermined threshold to put the switching means in operative condition; and means connecting the control electrode to the voltage-divider means and through unidirectional conducting means to the said other terminal of the thermocouple, so that a ground on either thermocouple terminal shifts the voltage on the control electrode to cause the switching means to override the amplifier.
Claim 5
Dependent Claim
18 words
A system as recited in claim 2 in which the voltage-divider means includes cold junction temperature compensating means.
Claim 6
Dependent Claim
142 words
A thermocouple amplifier effective to provide a recognizably spurious output in response to faults in the thermocouple circuit providing the input to the amplifier comprising, in combination, means for connection to a controlled-potential power source; a voltage divider connected across the source having a tap connected to the positive thermocouple lead; an operational amplifier having an output representing thermocouple emf and having an inverting input connected to the negative thermocouple lead side of the source; a switching circuit including a control input connected to the said voltage divider and having an output connected to the amplifier output and effective when the switching circuit turns on to override the amplifier, the switching circuit also having its said input connected through a unidirectional conductor to the negative thermocouple lead, so that grounding of either thermocouple lead operates the control input to override the amplifier.
Claim 7
Dependent Claim
142 words
A thermocouple amplifier effective to provide a recognizably spurious output in response to faults in the thermocouple circuit providing the input to the amplifier comprising, in combination, means for connection to a controlled-potential power source; a voltage divider connected across the source having a tap connected to the positive thermocouple lead; an operational amplifier having an output representing thermocouple emf and having an inverting input connected to the negative thermocouple lead side of the source; a switching circuit including a control input connected to the said voltage divider and having an output connected to the amplifier output and effective when the switching circuit turns on to override the amplifier, the switching circuit also having its said input connected through a unidirectional conductor to the negative thermocouple lead, so that grounding of either thermocouple lead operates the control input to override the amplifier.
Claim 8
Dependent Claim
220 words
A temperature-responsive system including a thermocouple circuit, an output line, and an amplifier coupling the thermocouple circuit to the output line, in combination with means operative in response to faults in the thermocouple circuit to provide a recognizably spurious signal in the output line, the said means comprising, in combination, means providing a resistive connection between one terminal of the thermocouple circuit and one side of a power supply circuit; voltage divider means providing resistive connections between the other terminal of the thermocouple circuit and both sides of the power supply circuit; the amplifier having a differential input connected to the two terminals of the thermocouple circuit, so that an open thermocouple circuit drives the amplifier output to the spurious value; switching means for connecting the output line to a source of potential of magnitude representing the spurious value; the switching means having a control input effective to close the switching means upon the occurrence of a predetermined threshold potential in the control input; unidirectional conducting means connecting the said control input to the said one terminal of the thermocouple circuit; and the control input being coupled through one of the resistive connections of the voltage divider means to the said other terminal of the thermocouple circuit, so that grounding either terminal of the thermocouple circuit closes the switching means.
Claim 9
Dependent Claim
220 words
A temperature-responsive system including a thermocouple circuit, an output line, and an amplifier coupling the thermocouple circuit to the output line, in combination with means operative in response to faults in the thermocouple circuit to provide a recognizably spurious signal in the output line, the said means comprising, in combination, means providing a resistive connection between one terminal of the thermocouple circuit and one side of a power supply circuit; voltage divider means providing resistive connections between the other terminal of the thermocouple circuit and both sides of the power supply circuit; the amplifier having a differential input connected to the two terminals of the thermocouple circuit, so that an open thermocouple circuit drives the amplifier output to the spurious value; switching means for connecting the output line to a source of potential of magnitude representing the spurious value; the switching means having a control input effective to close the switching means upon the occurrence of a predetermined threshold potential in the control input; unidirectional conducting means connecting the said control input to the said one terminal of the thermocouple circuit; and the control input being coupled through one of the resistive connections of the voltage divider means to the said other terminal of the thermocouple circuit, so that grounding either terminal of the thermocouple circuit closes the switching means.
Claim 10
Dependent Claim
167 words
A thermocouple amplifier effective to provide a recognizably spurious output in response to faults in the thermocouple circuit providing the input to the amplifier comprising, in combination, means for connection to a controlled-potential power source; a voltage divider connected across the source having a tap connected to one thermocouple lead; an operational amplifier having an output representing thermocouple emf and having an inverting input connected to the other thermocouple lead and connected through a resistor to one side of the source so that an open circuit between the thermocouple leads provides a strong simulated cold temperature signal to the amplifier; a switching circuit including a control input connected to the said voltage divider and having an output connected to the amplifier output and effective when the switching circuit turns on to override the amplifier, the switching circuit also having its said input connected through a unidirectional conductor to the other thermocouple lead, so that grounding of either thermocouple lead operates the control input to override the amplifier.
Claim 11
Dependent Claim
167 words
A thermocouple amplifier effective to provide a recognizably spurious output in response to faults in the thermocouple circuit providing the input to the amplifier comprising, in combination, means for connection to a controlled-potential power source; a voltage divider connected across the source having a tap connected to one thermocouple lead; an operational amplifier having an output representing thermocouple emf and having an inverting input connected to the other thermocouple lead and connected through a resistor to one side of the source so that an open circuit between the thermocouple leads provides a strong simulated cold temperature signal to the amplifier; a switching circuit including a control input connected to the said voltage divider and having an output connected to the amplifier output and effective when the switching circuit turns on to override the amplifier, the switching circuit also having its said input connected through a unidirectional conductor to the other thermocouple lead, so that grounding of either thermocouple lead operates the control input to override the amplifier.
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) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |