10

FIGURE 10. HI7106 USED AS A DIGITAL CENTIGRADE

THERMOMETER

FIGURE 11. CIRCUIT FOR DEVELOPING UNDERRANGE AND

OVERRANGE SIGNAL FROM HI7106 OUTPUTS

FIGURE 12. AC TO DC CONVERTER WITH HI7106

28

40

39

38

37

36

35

34

33

32

31

30

29

27

26

25

24

23

22

21

OSC 1

OSC 2

OSC 3

TEST

REF HI

REF LO

COMMON

IN HI

IN LO

A-Z

BUFF

INT

V -

G2

C3

A3

G3

BP

100pF

TO PIN 1

0.1

µF

0.01

µF

100k

Ω

100k

Ω 1MΩ

9V

47k

Ω

0.22

µF

0.47

µF

TO BACKPLANE

TO DISPLAY

NOTE: A silicon diode-connected transistor has a temperature coef-

ing transistor in ice water and adjusting the zeroing potentiometer for

a 000.0 reading. The sensor should then be placed in boiling water

and the scale-factor potentiometer adjusted for a 100.0 reading.

SCALE

FACTOR

ADJUST

100k

Ω 220kΩ

22k

Ω

SILICON NPN

MPS 3704 OR

SIMILAR

ZERO

ADJUST

13

1

2

3

4

5

6

7

8

9

10

11

12

14

15

16

17

18

19

20

V+

D1

C1

B1

A1

F1

G1

E1

D2

C2

B2

A2

F2

E2

D3

B3

F3

E3

AB4

POL

28

40

39

38

37

36

35

34

33

32

31

30

29

27

26

25

24

23

22

21

OSC 1

OSC 2

OSC 3

TEST

REF HI

REF LO

COMMON

IN HI

IN LO

A-Z

BUFF

INT

V-

G2

C3

A3

G3

BP

O /RANGE

U /RANGE

CD4023 OR

74C10

CD4077

TO LOGIC

V+

TO

LOGIC

V-

GND

28

40

39

38

37

36

35

34

33

32

31

30

29

27

26

25

24

23

22

21

OSC 1

OSC 2

OSC 3

TEST

REF HI

REF LO

COMMON

IN HI

IN LO

A-Z

BUFF

INT

V -

G2

C3

A3

G3

BP

100pF

TO PIN 1

0.1

µF

100k

Ω

1k

Ω

22k

Ω

47k

Ω

0.22

µF

0.47

µF

TO BACKPLANE

TO DISPLAY

NOTE: Test is used as a common-mode reference level to ensure compatibility with most op amps.

10

µF

9V

10

µF

470k

Ω

1

µF

4.3k

Ω

100pF

(FOR OPTIMUM BANDWIDTH)

1

µF

10k

Ω

10k

Ω

1N914

1

µF

0.22

µF

5

µF

CA3140

2.2M

Ω

+

-

100k

Ω

AC IN

SCALE FACTOR ADJUST

+

-