13

FN3082.7

FIGURE 17. ICL7107 MEASUREING RATIOMETRIC VALUES

OF QUAD LOAD CELL

FIGURE 18. ICL7106 USED AS A DIGITAL CENTIGRADE

THERMOMETER

FIGURE 19. CIRCUIT FOR DEVELOPING UNDERRANGE AND

OVERRANGE SIGNAL FROM ICL7106 OUTPUTS

FIGURE 20. CIRCUIT FOR DEVELOPING UNDERRANGE AND

OVERRANGE SIGNALS FROM ICL7107 OUTPUT

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

GND

100pF

TO PIN 1

0.1

µF

100k

Ω

0.47

µF

TO DISPLAY

The resistor values within the bridge are determined by the desired

sensitivity.

V+

0.22

µF

47k

Ω

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

A silicon diode-connected transistor has a temperature coefficient of

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

O/RANGE

U/RANGE

CD4023 OR

74C10

TO LOGIC

+5V

V-

33k

Ω

The LM339 is required to

ensure

logic

compatibility

with heavy display loading.

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

12k

Ω

+

-

+

-

+

-

+

-

LM339

ICL7106, ICL7107, ICL7107S