EDN -- 12.07.95 circuit linearizes, converts thermistor data

FIGURE 2

V_source	5.00V
R_pu	10, 000 Ohms
R₁	50, 000 Ohms
R_f	14, 640 Ohms
R_off	50, 000 Ohms
V_off	-3.165V
A_mp	29.28 V_o/V_i

Temp

RT(Ohms)

V(rt)

dV/dt

T_out

Error

-80

3, 558, 000

4.157

-29.04

-75

2, 440, 000

4.152

0.001

-28.91

-70

1, 694, 000

4.146

0.001

-28.73

-65

1, 190, 000

4.138

0.002

-28.48

-60

845, 900

4.126

0.002

-28.14

-55

607, 800

4.110

0.003

-27.68

-50

441, 300

4.089

0.004

-27.07

-45

323, 700

4.062

0.005

-26.27

-40

239, 800

4.027

0.007

-25.23

-35

179, 200

3.982

0.009

-23.91

-30

135, 200

3.925

0.011

-22.25

-25

102, 900

3.855

0.014

-20.19

4.81

-20

78, 910

3.769

0.017

-17.68

2.32

-15

61, 020

3.666

0.021

-14.67

0.33

-10

47, 540

3.545

0.024

-11.13

-1.13

-5

37, 310

3.406

0.028

-7.05

-2.05

0

29, 490

3.249

0.031

-2.45

-2.45

5

23, 460

3.075

0.035

2.65

-2.35

10

18, 790

2.887

0.038

8.15

-1.85

15

15, 130

2.687

0.040

14.00

-1.00

20

12, 260

2.481

0.041

20.04

0.04

25

10,000

2.273

0.042

26.13

1.13

30

8194

2.066

0.041

32.19

2.19

35

6752

1.865

0.040

38.07

3.07

40

5592

1.673

0.038

43.68

3.68

45

4655

1.493

0.036

48.95

3.95

50

3893

1.327

0.033

53.83

3.83

55

3270

1.174

0.030

58.29

3.29

60

2760

1.037

0.028

62.32

2.32

65

2339

0.913

0.025

65.93

0.93

70

1990

0.803

0.022

69.15

-0.85

75

1700

0.706

0.019

72.00

-3.00

80

1458

0.620

0.017

74.50

-5.50

85

1255

0.545

0.015

76.70

90

1084

0.480

0.013

78.63

An Excel spreadsheet allows you to play with various thermistors.
You enter the thermistor value and adjust the offset- and gain-resistor
values to achieve the desired circuit response.

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