Temperature measuring voltage to current converter

Claim 2

A temperature indicator comprising: a differential amplifier having noninverting and inverting inputs, and an output, said amplifier being actuable to produce an output voltage and an output current at the said output thereof; a D.C. source of potential having first and second poles; first and second input leads connected from said first and second poles, respectively; first and second resistors connected in series in that order from said first lead to said second lead, said first resistor being a temperature sensitive resistor; third and fourth resistors connected in series in that order from said first lead to said second lead, said noninverting amplifier input being connected from the mutual junction of said first and second resistors; an ammeter calibrated in temperature connected from said amplifier output to the mutual junction of said third and fourth resistors; means providing resistance between and connected between the mutual junction of said third and fourth resistors to said inverting amplifier input; and means providing resistance between and connected between said inverting amplifier input and said second lead.

Claim 3

The invention as defined in claim 1, wherein the resistance, R2, of said third resistor is defined by R2 EsRp/e2 where, Rp is the ratio of the input voltage span desired to the current range of said ammeter, Es is the voltage to be applied between said input leads, and e2 is the voltage at the mutual junction of said first and second resistors at which it is desired to produce zero current through said ammeter, the resistance, R3, of said fourth resistor being defined by R3 EsRp/Es - e2.

Claim 4

The invention as defined in claim 2, wherein said first and second poles are positive and negative, respectively.

Claim 5

A temperature indicator comprising: first and second input leads; a first resistor having a first lead connected from said first input lead, said first resistor being temperature sensitive, said first resistor having a second lead and a construction such that the potential of said second lead thereof will fall toward that of said second input lead when the temperature of said first resistor increases and said first input lead is maintained at a constant potential positive with respect to that of said second input lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and a second lead connected to said second input lead; a third resistor having a first lead connected from said first input lead, and a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and a second lead connected to said input lead; a differential amplifier having inverting and noninverting input leads, and an output lead; an ammeter connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead, said ammeter being calibrated in temperature; and a voltage divider including fifth and sixth resistors each having first and second leads, said voltage divider also including a potentiometer having a winding and a wiper on said winding, said winding having first and seconD leads, said fifth resistor first lead being connected from said fourth resistor first lead and said third resistor second lead, said fifth resistor second lead being connected to said winding first lead, said winding second lead being connected to said sixth resistor first lead, said sixth resistor second lead being connected to said second input lead, said wiper being connected to said amplifier inverting input lead, said amplifier noninverting input lead being connected from said second resistor first lead and said first resistor second lead.

Claim 6

A temperature indicator comprising: first and second input leads; a first resistor having a first lead connected from said first input lead, said first resistor being temperature sensitive, said first resistor having a second lead and a construction such that the potential of said second lead thereof will fall toward that of said second input lead when the temperature of said first resistor increases and said first input lead is maintained at a constant potential positive with respect to that of said second input lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and a second lead connected to said second input lead; a third resistor having a first lead connected from said first input lead, and a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and a second lead connected to said input lead; a differential amplifier having inverting and noninverting input leads, and an output lead; an ammeter connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead, said ammeter being calibrated in temperature; and a voltage divider including fifth and sixth resistors each having first and second leads, said voltage divider also including a potentiometer having a winding and a wiper on said winding, said winding having first and seconD leads, said fifth resistor first lead being connected from said fourth resistor first lead and said third resistor second lead, said fifth resistor second lead being connected to said winding first lead, said winding second lead being connected to said sixth resistor first lead, said sixth resistor second lead being connected to said second input lead, said wiper being connected to said amplifier inverting input lead, said amplifier noninverting input lead being connected from said second resistor first lead and said first resistor second lead.

Claim 7

The invention as defined in claim 4, including a D.C. source of potential and a first diode connected in series from one of said input leads to the other, said source being poled to maintain said first lead positive with respect to said second lead, said first diode being poled to be conductive in a direction from said second input lead to said first input lead, said amplifier having a positive power input lead connected from said first input lead and a negative power input lead connected to said second lead, and a second diode connected from said fourth resistor first lead and said third resistor second lead to said amplifier output lead and poled to be conductive in a direction toward said amplifier output lead.

Claim 8

A voltage to current converter comprising: first and second input leads; a first resistor having a first lead connected from said first input lead and a second lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and a second lead connected to said second input lead, at least one of said first and second resistors having a resistance which changes with a predetermined variable, a third resistor having a first lead connected from said first input lead, and a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and having a second lead connected to said second input lead; a differential amplifier having inverting and noninverting input leads, and an output lead; first means connecting said second resistor first lead and said first resistor second lead to one of said amplifier input leads; second means connecting said fourth resistor first lead and said third resistor second lead to the other of said amplifier input leads; and a current sensing device connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead.

Claim 9

A voltage to current converter comprising: first and second input leads; a first resistor having a first lead connected from said first input lead and a second lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and a second lead connected to said second input lead, at least one of said first and second resistors having a resistance which changes with a predetermined variable, a third resistor having a first lead connected from said first input lead, and a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and having a second lead connected to said second input lead; a differential amplifier having inverting and noninverting input leads, and an output lead; first means connecting said second resistor first lead and said first resistor second lead to one of said amplifier input leads; second means connecting said fourth resistor first lead and said third resistor second lead to the other of said amplifier input leads; and a current sensing device connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead.

Claim 10

The invention as defined in claim 6, wherein said first means connecting includes a conductor, said second means connecting including second means providing resistance between said fourth resistor first lead and said third resistor second lead and said other amplifier input lead, third means being provided and connected between said other amplifier input lead and said second input lead.

Claim 11

The invention as defined in claim 6, wherein said first means connecting includes a conductor.

Claim 12

The invention as defined in claim 6, wherein said second means connecting includes second means providing resistance between said fourth resistor first lead and said third resistor second lead and said other amplifier input lead, third means being provided and connected between said other amplifier input lead and said second input lead.

Claim 13

A temperature indicator comprising: first and second input leads; a first resistor having a first lead connected from said first input lead, and a second lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and having a second lead connected to said second input lead, at least one of said first and second resistors being temperature sensitive; a third resistor having a first lead connected from said first input lead, and having a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and a second lead connected to said second input lead; a conductor connecting said second resistor first lead and said fIrst resistor second lead to one of said amplifier input leads; a voltage divider having first and second series connected resistance legs connected from said second junction to said second input lead, said voltage divider having a tap connected to the other of said amplifier input leads; and an ammeter calibrated in temperature, said ammeter being connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead.

Claim 14

A temperature indicator comprising: first and second input leads; a first resistor having a first lead connected from said first input lead, and a second lead; a second resistor having a first lead forming a first junction with said first resistor second lead, and having a second lead connected to said second input lead, at least one of said first and second resistors being temperature sensitive; a third resistor having a first lead connected from said first input lead, and having a second lead; a fourth resistor having a first lead forming a second junction with said third resistor second lead, and a second lead connected to said second input lead; a conductor connecting said second resistor first lead and said fIrst resistor second lead to one of said amplifier input leads; a voltage divider having first and second series connected resistance legs connected from said second junction to said second input lead, said voltage divider having a tap connected to the other of said amplifier input leads; and an ammeter calibrated in temperature, said ammeter being connected from said amplifier output lead to said fourth resistor first lead and said third resistor second lead.