DLD Application Circuits

1. Decoder circuit using CD4511

4 5 1 1

7126

34

5

13

12

11

10

9 15

14

1 6

8

ABCD

L TB I

L E

a b c d e f g V D D

G N D

S1

HI

cathode chung

0

4 5 1 1

7126

34

5

13

12

11

10

9 15

14

1 6

8

ABCD

L TB I

L E

a b c d e f gV D D

G N D

0

S8

5V

1KX8

7-Segment Led decoder circuits:Common Cathode :

2. Decoding and display with TTL 74247

HI

150X17

5V

Anode chung

7 4 2 4 7

7126

34

5

13 12 11 10 9 15 14

1 6

8

ABCD

L TB I

L E

a b c d e f g V D D

G N D

S1 S8

0

7 4 2 4 7

7126

34

5

13 12 11 10 9 15 14

1 6

8

ABCD

L TB I

L E

a b c d e f gV D D

G N D

330X8

1

3. Counter circuit 0 to 23 using IC 7490

7 4 2 4 7

7126

34

5

13

12

11

10

9 15

14

1 6

8

ABCD

L TB I

L E

a b c d e f gV D D

G N D7 4 2 4 7

7126

34

5

13

12

11

10

9 15

14

1 6

8

ABCD

L TB I

L E

a b c d e f g V D D

G N D

150X17

0

5V

Anode chung

HI

U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

5V

U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

HI

C 2

0 . 0 1

C 1CR 3

1 0 0

0

giai ma vahien thi led7 doan

C 30 . 0 1

5V

R 21 5 0


D 1

L E D

500K

D 2

R 11 0 K5V U 3

L M 5 5 53

4 815

26

7

O U T

RS

TV

CC

GN

D

CV

TR GTH R

D S C H G

2

Decoding and

display 7segment

Decoding and display 7segment


4. Counter circuit 0 to 59 using IC 7490

R 21 5 0

0

R 11 0 K

500K


R 31 0 0

U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

HI

C 30 . 0 1

5V


5V

D 1

L E D

U 3

L M 5 5 53

4 815

26

7

O U T

RS

TV

CC

GN

D

CV

TR GTH R

D S C H G

C 1C

C 2

0 . 0 1

5V

D 2

U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

5. Counter UP/DOWN

u p U 3

7 4 2 4 7

7126

45

3

1 31 21 11 091 51 4

168

D 0D 1D 2D 3

BI/R

BORB

ILT A

BCDEFG

VCC

GND

5V

C 20 . 0 1

R 7

5 0 0 K

3 or 8

0

R 61 K

R 25 6 0

U 2

L M 5 5 5 3

4 81 5

26

7

O U T

RST

VCC

GND

CVTR GTH R

D S C H G

d o wn

R 15 6 0

C 11 M

HI

7 4 1 9 2 / 4 0 1 9 2

151 10 9

3267

168

1 4

11

5

4

P0P1 P2 P3

Q 0Q 1Q 2Q 3

VCC

GND

C L R

LOADC L K U

C L K D

R 31 K

re s e t

1 5 0 x 7

3



6. Count number of Cars in/out Garage using IR

D 3

L E D I R

D 2

le d t h u I R

0H

I

D 1

L E D I R

C 2

0 . 0 1

7 4 L S 1 9 2

3267

16814

11

5

4Q 0Q 1Q 2Q 3

VC

CG

ND

CLR

LOA

D

C L K U

C L K D

5V

D 6L E D

5V

R 52 7 0

U 3 A

7 4 L S 1 4

1 2

0

R 21 0 0

HI5V

R 11 0 0

0

R 31 0 0 K

U 5 B

7 4 L S 1 4

3 4

D 4

le d t h u I R

HI

7X150

C 1

0 . 0 1

5V

D 5

L E D

U 2

7 4 L S 2 4 7

7126

4 53

1 31 21 11 091 51 4

168

D 0D 1D 2D 3

BI/

RB

O

RB

ILT

ABCDEFG

VC

CG

ND

0

R 62 7 0

R 41 0 0 K

HI

0

4

7. MAÏCH ÑOÀNG HOÀ SOÁ DẠNG ÑÔN GIAÛN

D 1

L E D


U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

HIgiai ma va

hien thi led7 doan

5V

500K

R 21 5 0

U 3

L M 5 5 53

4 815

26

7

O U T

RS

TV

CC

GN

D

CV

TR GTH R

D S C H G

hien thi 60 giay

U 2

7 4 9 01 4

1 12 9 8 115

102 3 6 7

C L K A

CLK

BQ

AQ

BQ

CQ

D

VC

C

GN

D

R01

R02

R91

R92

7 4 0 8

1

23

C 2

0 . 0 1

D 2

5V

C 30 . 0 1

R 11 0 K

0

5V

C 11 MR 3

1 0 0

U 5 B

7 4 0 8

4

56

5V

U 2

7 4 9 01 4

1 12

9 8 11

5

10

2 3 6 7

C L K A

CL

KB

QA

QB

QC

QD

VC

C

GN

D

R0

1R

02

R9

1R

92

giai ma v ahien thi l ed7 doan


5V

0

U 2

7 4 9 01 4

1 12

9 8 11

5

10

2 3 6 7

C L K A

CL

KB

QA

QB

QC

QD

VC

C

GN

D

R0

1R

02

R9

1R

92

5V

U 2

7 4 9 01 4

1 12

9 8 11

5

10

2 3 6 7

C L K A

CL

KB

QA

QB

QC

QD

VC

C

GN

D

R0

1R

02

R9

1R

92

hien thi 60 phuthien thi 24 gio

0

U 2

7 4 9 01 4

1 12

9 8 11

5

10

2 3 6 7

C L K A

CL

KB

QA

QB

QC

QD

VC

C

GN

D

R0

1R

02

R9

1R

92



5V

8. MAÏCH GIAÛI MAÕ PHÍM SOÁ 1

5

8

U 3 A

7 4 0 0

1

23

0

5V

U 7

7 4 2 4 7

16

8

7126

4

35

1 31 21 11 091 51 4

VC

CG

ND

I N AI N BI N CI N D

B I / R B O

L TR B I

O U TAO U TBO U TCO U TDO U TEO U TFO U TG

0

0

7

U 4 A

7 4 0 0

1

23

so 2 den 6U 6 D

7 4 0 0

1 2

1 31 1

U 2

7 4 1 4 8

79

6

1 4

1 01 11 21 3

1234

5

16

8

1 5

A 1A 0

A 2

G S

I N 0I N 1I N 2I N 3I N 4I N 5I N 6I N 7

E I

VC

CG

ND

E O

0

7X150

9

1

U 1

7 4 1 4 8

79

6

1 4

1 01 11 21 3

1234

5

16

8

1 5

A 1A 0

A 2

G S

I N 0I N 1I N 2I N 3I N 4I N 5I N 6I N 7

E I

VC

CG

ND

E O

U 5 C

7 4 0 0

9

1 08

9. MAÏCH GIAÛI MAÕ PHÍM SOÁ 2

R 11 0 K

U 6

7 4 L S 2 4 7

7126

4 5 3

1 31 21 11 091 51 4

168

D 0D 1D 2D 3

BI/R

BO RBI LT

ABCDEFG

VCC

GN

D

5V

so 91 2

9 8

1 5 0 X7

3 4

9 ctac va 9 dtro

0

so 11 2

U 1

7 4 L S 1 4 7

7

9

6

1 4

1 11 21 3

12345

1 0

168

B

A

C

D

I N 1I N 2I N 3I N 4I N 5I N 6I N 7I N 8I N 9

VCC

GN

D

5 6

0

R 11 0 K

1 2

HI

10. MAÏCH GAME ÑOAÙN SOÁ

6

R 31 5 0

HI

S W 1

cac cong tac datso muon doan (0 den 15)

3 41 K

5V

U 3

7 4 H C 9 3

1 4 1

23

1 2981 1

510

C K A C K B

R 0 1R 0 2

Q AQ BQ CQ D

VCC

GN

D

U 2

7 4 2 4 7

168

7126

4

35

1 31 21 11 091 51 4

VCC

GN

D


B I / R B O

L TR B I


U 2

7 4 2 4 7

168

7126

4

35

1 31 21 11 091 51 4

VCC

GN

D


B I / R B O

L TR B I


8X150

5 6

8X150

U 1

L M 5 5 5

3

481 5

26

7

O U T

RST

VCC

GN

D

CVTR G

TH R

D S C H G

so dat

D 1

R 11 0 K

D 3

U 5

7 4 8 51

1 5

1 4

1 3

1 1

1 2

9

1 0

23

4

168

7

6

5

B 3

A 3

B 2

A 2

B 1

A 1

B 0

A 0

A<B_

INA=

B_IN

A>B_

IN

VCC

GN

D

A <B

A =B

A >B

5V

C 10 . 0 1 M

0

0

5 0 0 K

1 2

7 8

HI

so n

gau

nhie

n

D 2

11. MAÏCH ÑIEÀU KHIEÅN TÖØ XA DUØNG TIA HOÀNG NGOAÏI

U 1

L M 5 6 7

12

3

47

86

5

OU

T FI

L

LFIL

I N P U T

+VC

CG

ND

O U TP U TTC

TRR 5

1 K

U 2

L M 5 5 5

3

4815

26

7

O U T

RST

VCC

GN

D

CV

TR GTH R

D S C H G

C 10 . 3 3 M

C 20 . 0 1 M

C 40 . 1 M

0

R 3

1 0R 1

1 0 K

9V

R 44 7 K

D 1

9V

R 71 0 K

+

-

U 3

L M 7 4 1

4

26

7

3

C 61 MC 52 . 2 M

R 21 . 2 K

D 2

L E D

R 8 1 K

Q 1

R 6 1 0 0 K

C 3

0 . 1 M

12. MAÏCH ÑEÁM SAÛN PHAÅM

7

D 1

I R

R 3 1 K

U 5

7 4 2 4 7 A

7126

53

1 31 21 11 091 51 4

8

4

16


R B IL T


GN

D

B I / R B O

VC

C

HI

1 K

5V

0

R 6 1 0 0 K

9V

0

LED 7 DOAN

U 5

7 4 2 4 7 A

7126

53

1 31 21 11 091 51 4

8

4

16


R B IL T


GN

D

B I / R B O

VC

C

0 . 0 1

HI

7 4 1 4

1 2

71

4

4 7 0

le d

5V

U 6

7 4 9 0 A

6723

1 4

1

1 2981 1

51

0

R 9 1R 9 2R 0 1R 0 2

C K A

C K B

Q AQ BQ CQ D

VC

CG

ND

+

-

U 3

L M 7 4 1

4

26

7

31 0 K

0

U 6

7 4 9 0 A

6723

1 4

1

1 2981 1

51

0

R 9 1R 9 2R 0 1R 0 2

C K A

C K B

Q AQ BQ CQ D

VC

CG

ND

R 2 1 K

5V

Q 1

D 2

I R

LED 7 DOAN

1 K

0

2 N 3 9 0 4 A

31

2

4 7 K

13. MAÏCH ÑEØN GIAO THOÂNG 1

8

500K

C 20 . 0 1 M

0

L M 5 5 5 3

4 8

1 5

26

7

O U T

RS

TV

CC

GN

D

CV

TR GTH R

D S C H G HI

den xanh

9V

den vang

0 100

HI

150

1500

den vang

den xanh

den do

9V

Q 2

den do

Q 1

1 0 K

0

U 3

4 0 1 7

1 4

1 31 5

3247

1 0

1569

1 1

1 2

16

8

C L K

E N AR S T

Q 0Q 1Q 2Q 3

Q 4

Q 5Q 6Q 7Q 8

Q 9

C O

VC

C

G N D

C 11 M

14. MAÏCH SAÙNG DAÀN – TAÉT DAÀN

HI

1 K

C 20 . 0 1R 1

1 0 KU 1

7 4 1 6 4

7

14 1

2

83 4 56 10 11 12 13

9

GN

D

VCC A

B

CLK

QA

QB

QC

QD

QE

QF

QG

QH

CLR

0

U 17 4 1 6 4

7

14

1

283 4 56 10 11 12 13

9

GN

D

VCC

A

B

CLK

QA

QB

QC

QD

QE

QF

QG

QH

CLR

R 31 K

L M 5 5 5 3

4 8

1 5

26

7

O U T

RST

VCC

GN

D

CVTR G

TH R

D S C H G

5V

3 3

C 1 8 1 5 A

31

2

R5

500K

0

C 1

1 M

C 30 . 0 1 M


9

1 5 0

red

U 9 D1 2

1 31 1

1 5 0

red

blue

red

1 N 4 1 4 8 X 6

D I O D E

U 5 A

7 4 1 0 7

1

4

13

3

21 2

J

K

CLR

Q

QC L K

U 2

7 4 1 4 5

123456791 01 1

168

1 51 4

1 3

1 2Q 0Q 1Q 2Q 3Q 4Q 5Q 6Q 7Q 8Q 9VCC

GND

AB

C

D

green

R 5

500K

U 1

7 4 1 4 5

123456791 01 1

168

1 51 4

1 3

1 2

Q 0Q 1Q 2Q 3Q 4Q 5Q 6Q 7Q 8Q 9

VCCGND

AB

C

D

East --- WestC 30 . 0 1

C 11 M

yellow

1 5 0

R 11 0 K

1 5 0

greenU 7 B

4

56

0

R 21 5 0

U 8 C

9

1 08

1 5 01 5 0

yellow

U 6 A1

23U 4

7 4 9 0

1 411 2981 1

510

2367

C L K AC L K B

Q AQ BQ CQ D

VCCGND

R 0 1R 0 2R 9 1R 9 2

green

1 5 0

1 5 0

North --- South

0

U 3

L M 5 5 5 3

481 5

26

7

O U T

RSTVCCGND CVTR G

TH R

D S C H G


10

green

North --- South

U 1

7 4 1 4 5

12345

6791 0

1 1

168

1 51 41 31 2

Q 0Q 1Q 2Q 3Q 4

Q 5Q 6Q 7Q 8

Q 9

VCCGND

ABCD

1 5 0

C 11 M

0

red

1 5 0

red

Yellow

East --- West

1 5 0

1 5 0

5V

C 30 . 0 1

1 N 4 1 4 8 X 4D I O D E

U 3

L M 5 5 5 3

481 5

26

7

O U T

RSTVCCGND CVTR G

TH R

D S C H G

R 21 5 0

1 5 0

R 11 0 K

green

1 5 0

R 5

500K

1 5 0

yellow

1 5 0

HI

U 4

7 4 9 0

1 411 2981 1

510

2367

C L K AC L K B

Q AQ BQ CQ D

VCCGND

R 0 1R 0 2R 9 1R 9 2

17. MAÏCH COÄNG – TRÖØ ÑÔN GIAÛN

11

1 2

R 31 K

resist

er B

S W 1 0

1 2

U 1

74LS147 7

9

6

1 4

1 11 21 3

12345

1 0

168

B

A

C

D

I N 1I N 2I N 3I N 4I N 5I N 6I N 7I N 8I N 9

VCCGN

D

clock

S W 1

1 5 0

9

1 08

S W 1 1

1 2

S W 1 21 2

0

1

23

0

U 3

74LS83A

138

1 0

1 647

1 1

1 3

1 4

1 5269

512

A 4A 3A 2A 1

B 4B 3B 2B 1

C 0

C 4

S U M 4S U M 3S U M 2S U M 1

VCCGN

D

0

HI

U 77 4 L S 1 9 4 A

109

3456

1 5

1 3

1 1

816

1 4

1 2

1S1S0

ABCD

Q A

Q C

C L K

GND

VCC

Q B

Q D

CLR

7 4 L S 0 4

1 2R 11 5 0

0

7 4 8 61 2

1 31 1

1 2

5V

1 2

S W 1 3

1 2

0

1 5 0

So B

U 2

7 4 L S 1 9 4 A

1 09

3456

1 5

1 3

1 1

816

1 4

1 2

1

S 1S 0

ABCD

Q A

Q C

C L K

GND

VCC

Q B

Q D

CLR

0

5V

R 4R

1 k

So A

5V

U 1 2

7 4 L S 2 4 7

7126

53

1 31 21 11 091 51 4

8

4

16


R B IL T


GND

B I / R B O

VCC

S W 9

R 21 K

5V

4

56

R 5R

7X150

HI

1 k

resist

er A

HI

0

18. MAÏCH GAME XÚC XắC

12

D 1

L E D

12V

U 4 C

C D 4 0 9 3 B

8

91 0

0

Q 6

2 N 3 9 0 6

C 1 1 0 M

12V

S W 1

D2

R 3 3 3 0 K

D1

D 4

D3D4

R 1 2 . 2 K

0

R 1 3 3 9 0

D5

D 3

Q 12 N 3 9 0 4

R 9 4 7 K

D 2

D7

1 N 9 1 4

D 5

D6

U 1

C D 4 0 2 9 A

5

1 5

9

61 11 4

7

168 104

12133

1

CIN

C L K

BIN/DE

C

Q 1Q 2Q 3

C O U T

VDDVSS UP/

DOWN

JAM1

JAM2

JAM3

JAM4

P S E N

HI

OUTPUT

0

C 2

0 . 0 4 7 M

HI

R 21 0 K

R 1 01 5 0

R 7 4 . 7 K

0

R 6 4 7 K

Q 42 N 3 9 0 4

U 3 B

C D 4 0 9 3 B

5

64

Q 32 N 3 9 0 4

R 4

1 0 0 K

R 5 6 8 K

D 6

D 7

0

U 8 AC D 4 0 1 6 B

1 2

13

I N / O U T O U T/ I N

CTRL

0

U 2 A

C D 4 0 9 3 B

1

23

Q 52 N 3 9 0 6

R 8

4 7 K

U 1 0 CC D 4 0 1 6 B

4 3

5

I N / O U T O U T/ I N

CTRL

R 1 2 6 8 0

R 1 1 8 2 0

19. MAÏCH BAÛNG ÑIEÅM THEÅ THAO

13

S W 3

reset

U 1 D1 2

1 31 1

1 K

U 2 7 4 L S 2 4 71 6

8

7 1 2 643 5

13

12

11

10

9 15

14

V C CG N D

INA

INB

INC

IND

BI/

RB

O

LT

RB

I

OU

TA

OU

TB

OU

TC

OU

TD

OU

TE

OU

TF

OU

TG

-1

+1

R

HI

R 5 1 K

5V

U 1 A

1

23

S W 1

U 47 4 L S 1 9 2

5

4

14

1 1

15

1 10

93 2 6 71

31

2

1 6

8

U P

D O W N

CL

RL O A D

A B C DQ

AQ

BQ

CQ

D

BO

CO

V C C

GN

D

R 3 1 K

R

S W 2U 5

7 4 L S 1 9 2

5

4

14

11

15

1 10

93 2 6 7

1 3

1 2

16

8

U P

D O W N

CL

R

LO

AD

A B C DQ

AQ

BQ

CQ

D

B O

C O

VC

C

GN

D

0

R 4 1 K

R 2 1 K

U 1 C9

1 08

U 3

7 4 L S 2 4 71 68

7 1 2 643 5

13

12

11

10

9 15

14

V C CG N D

INA

INB

INC

IND

BI/

RB

O

LT

RB

I

OU

TA

OU

TB

OU

TC

OU

TD

OU

TE

OU

TF

OU

TG

R 1 2R

U 1 B

7 4 0 0

4

56

20. MAÏCH KIEÅM TRA CÖÛA 1

14

D 1

D 9

1 K

5V U 2

7 4 H C 1 3 8

1 51 41 31 21 11 0971

5

23

6

416

8

Y 0Y 1Y 2Y 3Y 4Y 5Y 6Y 7A

G 2 B

BC

G 1

G2A

VCC

GN

D0

S W 81 2

16 LED

1 0 K

7 4 H C 1 3 8

1 51 41 31 21 11 097

1

5

23

6

4

16

8

Y 0Y 1Y 2Y 3Y 4Y 5Y 6Y 7

A

G 2 B

BC

G1

G 2 A

VCC

GN

D

S W 1 61 2

C 2

0 . 1 M

5V

RESET

LO

1 K

5 0 0 K

1 K

D 8

D 1 6

U 4

7 4 H C 1 5 1

711 10 9

6

16

8

543

1 51

1 41 31 2

2

GA B C

W

VCC

G N D

YD 0D 1

D 4D 3

D 5D 6D 7

D 2

16 C

ONG

TAC

VA 1

6 DT

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DIGITAL STOPWATCH 0-99SEC

29

Introduction

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In the present article, we will describe the function of a digital stopwatch, 0 – 99 sec. The function of the stopwatch, relies in the use of 4 integrated circuits, which in this case belong to National Semiconductor (http :// www . national . com ). It is obvious that other integrated circuits can be used to achieve the same result, however in this case we have used the following parts:

Α. 1 x CD4060BM (14 stage ripple carry binary counter)B. 1 x CD4040BM (14 stage ripple carry binary counter)C. 1 x MC14518B (BCD counter)D. 2 x MC14511B (BCD to seven segment driver)E. 2 x 7 segment LED displays

The circuit that has been used is shown in picture 1. Through the experimental part we will explain each of the parts function, but in order to have a notion of the basic idea, let just say, that this circuit besides the 5V power supply, is fed with a pulse which comes from a crystal. The crystal’s pulse is devided properly in order to obtain the 1 Hz pulse which we need in order for the circuit to work properly, and display the seconds on the 7 segment displays, through a procedure which we will explain through the experimental part.

We will begin the description of the digital circuit above. For our convenience we will devide the circuit to 2 parts: the generator, which produces the pulse of the desired frequency, and the part that does the actual counting.

Generator: The generator of the circuit comprises of the integrated circuits CD4040CM and CD4060CM. We use a crystal which oscillates at a frequency of 4,194,304MHz. It is obvious that this frequency is completely useless, as it is too big to be used as it is to our circuit. What we should is devide this frequency, in a way that in its final form, the pulse will have a frequency of 1Hz, which is the desirable frequency. Initially we use the integrated CD4060, which devides the imported frequency in its input, by forces of 2. As we can see on the integrated circuit the outputs are marked as Q4, Q5,… Qn. By importing a pulse in the CLK input of the 4060, with a frequency f Hz, we take out of output Qn, a signal which has a frequency equal to f/2n,. So, by exporting the signal out of Q14, knowing that the imported

signal has a frequency of 4,194,304Hz, we take a signal, which has a frequency of 256Hz.

By importing this signal, to 4040 and by exporting the signal through Q8 we have finally taken an inverted signal, at the frequency of 1Hz. The fact that the signal is inverted, firstly doesn’t affect the proper function of our circuit and secondly is due to the inversion of the CLK input as we can see. This inversion just causes, the following circuit to be triggered with a logical “0”. By putting a LED on the same output, we have a visual of the counting, as in each positive pulse the diode polarizes positively, and a current passes through it.

Counter: The signal of 1Hz, which we have taken from the generator, is imported to a BCD counter MC14518. This integrated circuit adds a logical “1” at each pulse, on its output.του. .The MC14518 is virtually divided into two segment. One counts the units of the seconds, while the other the decades. As we can see in picture 1, the generators pulse is imported to the part which counts the units. This is very logical, as we want in each secont the number of the display to be raised by 1. On the other hand, we want the first display to raise by 1, every 10 seconds. This is why, we ground the CLK input, and we use the signal of Q3 to the CKE input.

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http://www.national.com/

By using this means, we make sure that the first display will be triggered, only when we have a decreasing signal on Q3; that is, only when the signal drops from logical “1” to logical “0”. As we can see, the first display increments every 10 seconds, which means that after 9 on the second display (1001 on the output of the BCD counter) the first display must be set to zero, while the first must be set to +1. That is that from 1001 0000, and we have a descending pulse, as the last digit descends from logical “1” to logical “0” and triggers the BCD counter of the decades. When the decades display becomes 9 then the circuit goes to the next state, which is zero, and the counting begins once more.

The integrated circuits MC14511 are BCD to 7 segment drivers. As its name clearly state, their sole purpose is to translate the BCD information of MC14518, to a code understandable by the 7 segment displays. The inputs (Lamp Test, Blanking) are used to test the LEDs of the display and pulse modulate the brightness of the display. In this case we these inputs to logical “0”, as we don’t need them. The LE input (Latch Enable) is used to keep the number of the displays while the pulse still runs. It is a HOLD function similar to the one of the modern stopwatches.

In addition, at any given moment we can restart the counting, by pressing the reset switch. By this means we set the RST input of the MC14518 to logical “1”, which resets the counting to 0000.

DIGITAL STOPWATCH 0-60SEC

Introduction

By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 – 99sec stopwatch to a 0 – 60sec stopwatch.

We must find a way to control the RESET function of the BCD counter, which is responsible for the counting of the seconds. As we studied above, the circuit resets when we have 99 to 100, that is 1001 1001 0001 0000 0000. To make a transformation successfully we must force the pulse from 59 to 60 0011 1001 0100 0000 on the output of the BCD counter.

By placing the AND gate, with its inputs on the Q1 and Q2 of the BCD counter of the decades, we make sure that when the gate closes, the RST input of the BCD counter will be set to logical “1”, which on its turn, will force the circuit to start over. The transformed circuit appears in picture 2.

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http://www.electronics-lab.com/projects/oscillators_timers/014/index.html

http://www.electronics-lab.com/projects/oscillators_timers/014/index.html

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DIGITAL VOLTMETER

The ICL7107 is a 3 1/2 digit LED A/D convertor. It contains an internal voltage reference, high isolation analog switches, sequential control logic, and the display drivers. The auto-zero adjust ensures zero reading for 0 volts input.

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Example Circuits:44

I have placed a couple of 555 circuit examples below for your convenience. Play with different component values and use the formulas mentioned earlier to calculate your results. Things to remember: For proper monostable operation with the 555 timer, the negative-going trigger pulse width should be kept short compared tot he desired output pulse width. Values for the external timing resistor and capacitor can either be determined from the previous formulas. However, you should stay within the ranges of resistances shown earlier to avoid the use of large value electrolytic capacitors, since they tend to be leaky. Otherwise, tantalum or mylar types should be used. (For noise immunity on most timer circuits I recommend a 0.01uF (10nF) ceramic capacitor between pin 5 and ground.) In all circuit diagrams below I used the LM555CN timer IC from National, but the NE555 and others should not give you any problems.

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Circuits 1 to 10a:Play with different indicating devices such as bells, horns, lights, relays, or whatever (if possible). Try different types of LDR's. If for any reason you get false triggering, connect a ceramic 0.01uF (=10nF) capacitor between pin 5 (555) and ground. Keeping the basic rules of the 555 timer, try different values for

46

Ct and Rt (or the C & R over pins 2, 6 & 7) Replace Rt with a 1 megohm potentiometer if you wish. Make notes of the values used and use the formulas to calculate timing. Verify your calculations with your timing.

Fig. 1, Dark Detector: It will sound an alarm if it gets too dark all over sudden. For example, this circuit could be used to notify when a lamp (or bulb) burns out. The detector used is a regular cadmium-sulphide Light Dependent Resistor or LDR, for short, to sense the absence of light and to operate a small speaker. The LDR enables the alarm when light falls below a certain level.

Fig. 2, Power Alarm: This circuit can be used as a audible 'Power-out Alarm'. It uses the 555 timer as an oscillator biased off by the presence of line-based DC voltage. When the line voltage fails, the bias is removed, and the tone will be heard in the speaker. R1 and C1 provide the DC bias that charges capacitor Ct to over 2/3 voltage, thereby holding the timer output low (as you learned previously). Diode D1 provides DC bias to the timer-supply pin and, optionally, charges a rechargeable 9-volt battery across D2. And when the line power fails, DC is furnished to the timer through D2.

Fig. 3 Tilt Switch: Actually really a alarm circuit, it shows how to use a 555 timer and a small glass-encapsulated mercury switch to indicate 'tilt'.The switch is mounted in its normal 'open' position, which allows the timer output to stay low, as established by C1 on startup. When S1 is disturbed, causing its contacts to be bridged by the mercury blob, the 555 latch is set to a high output level where it will stay even if the switch is returned to its starting position. The high output can be used to enable an alarm of the visual or the audible type. Switch S2 will silent the alarm and reset the latch. C1 is a ceramic 0.1uF (=100 nano-Farad) capacitor.

Fig. 4, Electric Eye Alarm: The Electric-Eye Alarm is actually a similar circuit like the Dark Detector of Fig. 1. The same type of LDR is used. The pitch for the speaker can be set with the 500 kilo-ohm potentiometer. Watch for the orientation of the positive (+) of the 10uF capacitor. The '+' goes to pin 3.

Fig. 5, Metronome: A Metronome is a device used in the music industry. It indicates the rhythm by a 'toc-toc' sound which speed can be adjusted with the 250K potentiometer. Very handy if you learning to play music and need to keep the correct rhythm up.Error fixed with thanks to Grant Fair in regards to the two resistors. (Grant also added a PNP power transistor to increase the volume and a led for visual as well as sound output).

Fig. 6, CW Practice Oscillator: CW stands for 'Continuous Wave' or Morse-Code. You can practice the morse-code with this circuit. The 100K potmeter is for the 'pitch' and the 10K for the speaker volume. The "Key" is a morse code key.

Fig. 7, CW Monitor: This circuit monitors the morse code 'on-air' via the tuning circuit hookup to pin 4 and the short wire antenna. The 100K potmeter controls the tone-pitch.

Fig. 8, Ten-Minute Timer: Can be used as a time-out warning for Ham Radio. The Federal Communications Commission (FCC) requires the ham radio operator to identify his station by giving his call-sign at least every 10 minutes. This can be a problem, especially during lengthy conversations when it is difficult to keep track of time. The 555 is used as a one-shot so that a visual warning indicator becomes active after 10-minutes. To begin the cycle, the reset switch is pressed which causes the 'Green' led to light up. After 10 minutes, set by the 500K potentiometer R1, the 'Red' led will light to warn the operator that he must identify.

Fig. 9, Schmitt Trigger: A very simple, but effective circuit. It cleans up any noisy input signal in a nice, clean and square output signal. In radio control (R/C) it will clean up noisy servo signals caused by rf interference by long servo leads. As long as R1 equals R2, the 555 will automatically be biased for any supply voltage in the 5 to 16 volt range. (Advanced Electronics: It should be noted that there is a 180-degree

47

phase shift.) This circuit also lends itself to condition 60-Hz sine-wave reference signal taken from a 6.3 volt AC transformer before driving a series of binary or divide-by-N counters. The major advantage is that, unlike a conventional multivibrator type of squares which divides the input frequency by 2, this method simply squares the 60-Hz sine wave reference signal without division.

Fig. 10, Better Timing: Better and more stable timing output is created with the addition of a transistor and a diode to the R-C timing network. The frequency can be varied over a wide range while maintaining a constant 50% duty-cycle. When the output is high, the transistor is biased into saturation by R2 so that the charging current passes through the transistor and R1 to C. When the output goes low, the discharge transistor (pin 7) cuts off the transistor and discharges the capacitor through R1 and the diode. The high & low periods are equal. The value of the capacitor (C) and the resistor (R1 or potmeter) is not given. It is a mere example of how to do it and the values are pending on the type of application, so choose your own values. The diode can be any small signal diode like the NTE519, 1N4148, 1N914 or 1N3063, but a high conductance Germanium or Schottky type for the diode will minimize the diode voltage drops in the transistor and diode. However, the transistor should have a high beta so that R2 can be large and still cause the transistor to saturate. The transistor can be a TUN (europe), NTE123, 2N3569 and most others.

Fig. 10a, Missing Pulse Detector (Basic): This transistor can be replaced with a ECG or NTE159. This is just a basic model but works. Experiment with the values of Resistor and Capacitor. A good example would

be the 'Crashed Aircraft Locator' beacon used in radio control. If there is no signal it sees it as a missing pulse and sounds buzzer.

The following circuits are examples of how a 555 timer IC assist in combination with another Integrated Circuit. Again, don't be afraid to experiment. Unless you circumvent the min and max parameters of the 555, it is very hard to destroy. Just have fun and learn something doing it.

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Circuits 11 to 14:Play with different indicating devices such as bells, horns, lights, relays, or whatever (if possible). Try different types of LDR's. If for any reason you get false triggering, connect a ceramic 0.01uF (=10nF) capacitor between pin 5 (555) and ground. In all circuit diagrams below I used the LM555CN timer IC from National. The 555 timer will work with any voltage between 3.5 and 15volt. A 9-volt battery is usually a general choice. Keeping notes is an important aspect of the learning process.

Fig. 11, Two-Tones: The purpose of this experiment is to wire two 555 timers together to create a 2-note tone. If you wish, you can use the dual 556 timer ic.

Fig. 12, Recording Beep: This circuit is used to keep recording of telephone conversations legal. As you may know, doing otherwise without consent of the other party is illegal. The output of IC1 is fed to the 2nd 555's pin 3 and made audible via C2 and the speaker. Any 8-ohm speaker will do.

Fig. 13, Coin Toss: Electronic 'Heads-or-tails' coin toss circuit. Basically a Yes or No decision maker when 49

you can't make up your mind yourself. The 555 is wired as a Astable Oscillator, driving in turn, via pin 3, the 7473 flip-flop. When you press S1 it randomly selects the 'Heads' or 'Tails' led. The leds flashrate is about 2Khz (kilo-Hertz), which is much faster than your eyes can follow, so initially it appears that both leds are 'ON'. As soon as the switch is released only one led will be lit.

Fig. 14, Logic Probe: Provides you with three visible indicators; "Logic 1" (+, red led), "Logic 0" (-, green led), and "Pulse" (yellow led). Good for TTL and CMOS. The yellow or 'pulse' led comes on for approximately 200 mSec to indicate a pulse without regards to its width. This feature enables one to observe

a short-duration pulse that would otherwise not be seen on the logic 1 and 0 led's. A small switch (subminiature slide or momentary push) across the 20K resistor can be used to keep this "pulse" led on permanently after a pulse occurs.In operation, for a logic 0 input signal, both the '0' led and the pulse led will come 'ON', but the 'pulse' led will go off after 200 mSec. The logic levels are detected via resistor R1 (1K), then amplified by T1 (NPN, Si-AF Preamplifier/Driver), and selected by the 7400 IC for what they are. Diode D1 is a small signal diode to protect the 7400 and the leds from excessive inverse voltages during capacitor discharge.For a logic '1' input, only the logic '1' led (red) will be 'ON'. With the switch closed, the circuit will indicate whether a negative-going or positive-going pulse has occurred. If the pulse is positive-going, both the '0' and 'pulse' led's will be on. If the pulse is negative-going, the '1' and 'pulse' led's will be on.

Check the listing in Table 2. It shows some variations in the 555 manufacturing process by two different manufacturers, National Semiconductor and Signetics Corporation. Since there are other manufacturers then those two I suggest when you build a circuit to stick with the particular 555 model they specify in the schematic.Unless you know what you're doing of course... [grin].

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12 Volt 30 Amp PSUUsing a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps. The design is shown below:

Notes:The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) so that the regulator can maintain its output. If a transformer is used, then the rectifier diodes must be capable of passing a very high peak forward current, typically 100amps or more. The 7812 IC will only pass 1 amp or less of the output current, the remainder being supplied by the outboard pass transistors. As the circuit is designed to handle loads of up to 30 amps, then six TIP2955 are wired in parallel to meet this demand. The dissipation in each power transistor is one sixth of the total load, but adequate heat sinking is still required. Maximum load current will generate maximum dissipation, so a very large heat sink is required. In considering a heat sink, it may be a good idea to look for either a fan or water cooled heat sink. In the event that the power transistors should fail, then the regulator would have to supply full load current and would fail with catastrophic results. A 1 amp fuse in the regulators output

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prevents a safeguard. The 400mohm load is for test purposes only and should not be included in the final circuit. A simulated performance is shown below:

Calculations:This circuit is a fine example of Kirchoff's current and voltage laws. To summarise, the sum of the currents entering a junction, must equal the current leaving the junction, and the voltages around a loop must equal zero. For example, in the diagram above, the input voltage is 24 volts. 4 volts is dropped across R7 and 20 volts across the regulator input, 24 -4 -20 =0. At the output :- the total load current is 30 amps, the regulator supplies 0.866 A and the 6 transistors 4.855 Amp each , 30 = 6 * 4.855 + 0.866. Each power transistor contributes around 4.86 A to the load. The base current is about 138 mA per transistor. A DC current gain of 35 at a collector current of 6 amp is required. This is well within the limits of the TIP2955. Resistors R1 to R6 are included for stability and prevent current swamping as the manufacturing tolerances of dc current gain will be different for each transistor. Resistor R7 is 100 ohms and develops 4 Volts with maximun load. Power dissipation is hence (4^2)/200 or about 160 mW. I recommend using a 0.5 Watt resistor for R7. The input current to the regulator is fed via the emitter resistor and base emitter junctions of the power transistors. Once again using Kirchoff's current laws, the 871 mA regulator input current is derived from the base chain and the 40.3 mA flowing through the 100 Ohm resistor. 871.18 = 40.3 + 830. 88. The current from the regulator itself cannot be greater than the input current. As can be seen the regulator only draws about 5 mA and should run cold.

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Increasing Regulator Current

Notes: Although the 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant voltage. Currents up to 650mA will flow through the regulator, above this value and the power transistor will start to conduct, supplying the extra current to the load. This should be on an adequate heat sink as it is likely to get rather hot. Suppose you use a 12v regulator, 7812. The input voltage should be a few volts higher to allow for voltage drops. Assume 20 volts. Lets also assume that the load will draw 5amps. The power dissipation in the transistor will be Vce * Ic or (20-12)*8=40watt. It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation.

If you want to increase the output current with a negative regulator, such as the 79xx series, then the circuit is similar, but an NPN type power transistor is used instead.

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7812: 1=IN, 2=GND, 3=OUT. 7912: 1=GND, 2=IN, 3=OUT.

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Traffic Light Control Circuit

(20 Output Sequencing Circuit)

This page features a circuit that has twenty open collector outputs that turn on one at a time in a continuous sequential manner. The circuit make use of the 74LSxx family of TTL integrated logic devices. The circuits are designed to drive light emitting diodes or low current, low voltage incandescent lights but can also drive other loads of up to 80 milliamps.

20 Output Sequencing Circuit

The following schematic is for the 20 Output Sequencing Circuit. This circuit is the same as the one on the printed circuit board offered through this site.

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Basic Circuit Operation

The circuit is stepped through the sequence by an adjustable LM555 astable oscillator. The Oscillators output is divided by a 74LS90 divider into a 10 step BCD weighted output.

The BCD output then drives two 74LS145 - 1 of 10 decoders (See Notes) that are used to produce a 1 of 20 step output sequence.

Notes

The circuit does not drive the 74LS145's directly but uses a JK Flip-Flop (74LS107) and four - dual input OR gates (74LS32) to control to the inputs to the two output drivers (74LS145) This arrangement alternately creates disallowed states in these devices. The disallowed states prevent any of the ten outputs on that particular device from being turned ON while the other 74LS145 is in counting to ten.

This produces a system where only one of the 74LS145's is able to produce LOW output states at a time. In essence the circuit counts to 10 twice in succession rather than counting to 20 in a single cycle.

This may seem like an unusual method but it allows the circuit to economically make use of the open collector outputs of the 74LS145s decoder/drivers rather than having to use output buffer ICs.

The TTL logic devices requires a regulated 5 volt supply but the outputs of the 74LS145's can be supplied from up to 15 Volts with a maximum current of 80 milliamps.

The circuit above is shown in a continuous running mode. The circuit can also be externally stopped and reset.

Parts List The following is a parts list for use with the 20 Output Sequencing Circuit. Mouser Electronics part numbers are shown but the parts may be available from other sources as well. Suppliers that handle 'NTE' components should be able to get the ICs.

PART NUMBER

DESCRIPTION Mouser Part #

QTY

VR 1 Voltage Regulators TO-92 5.0V 0.1A

511-L78L05ABZ

1

IC 1 Timers DIP-8 Single Timer 512-LM555CN 1

IC 2 DECADE COUNTER DIP14 526-NTE74LS90

1

IC 3 QUAD 2-IN OR DIP-14 526-NTE74LS32

1

IC 4 DUAL J-K F/F DIP-14 526-NTE74LS107

1

IC 5, 6 BCD-DEC DECODER DP16 595-SN74LS145N

2

R1 100K ohm / 1/4 Watt Carbon Resistor

- 1

R2 Trimmer Potentiometers 1Mohms 6mm

531-PT6KV-1M

1

R3 470 ohm / 1/4 Watt Carbon Resistor

- 1

C1, C4 Radial Electrolytic Capacitors 140- 2

56

25V 10uF XRL25V10

C2 Radial Monolithic Capacitors 50V .1uF

581-SR215C104K

1

C3 Radial Electrolytic Capacitors 25V 1.0uF

140-XRL25V1.0

1

D1 LED - 3mm or 5mm - 1

- 2 Position Terminal Block - 5mm

- 1

20 Step LED Circuit

The next diagram shows a simple 20 LED driver circuit. Only one current limiting resistor is needed as only one LED can be on at a time.

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20 Step Traffic Light Schematic

The next diagram shows a traffic Light Control circuit.

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As shown, the traffic light circuit allows the lights in one direction to be GREEN for 7 steps of the counter, Yellow for 2 steps and RED for 1 step before the light turns GREEN in the opposite direction. Other light sequence steps can be created by shifting the circuits outputs as long as the total equals twenty. The RED signals of one direction are slaved to the GREEN, YELLOW and RED of the other direction though diodes.

Advanced GREEN lighting could be added but the flashing would have to be done externally to the PCB circuit.

20 Output Sequencing Circuit PCB20 Output Sequencing Circuit PCB - Assembled Example

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The printed circuit board is 2.9 inches square and has been commercially made.

The picture shows the circuit board wired for continuous running for the Traffic Light Control circuit. Other modes of operation will be shown in diagrams lower on the page.

Additional Circuits

The next diagram and image shows external controls that can be used to Start or Stop and Reset the circuit. When the circuit is reset the 555 clock will stop and the number 1 output will go to a LOW state.

If the RESET terminal is held LOW the circuit will run continuously. The RUN terminal has limitations (CLOCK input of the 74LS107) that are described on the data sheet for the device.

The next photo shows the location of the RUN and RESET connections on the circuit board. A jumper normally between the RUN connection and the circuit common must be removed first. Also shown are 5 volt and common connections that can be used to power external circuitry.

If the 555 timer is removed an external clock could be used to step the circuit. Alternately the circuit's 555 clock could provide an output to and external circuit.

Please Read Before Using These Circuit Ideas

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The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.

If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.

Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.

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