Page 145

16

5 1f

6

1g

7 8

NC 13

1c

12

1b

11

1e

10

1a

9

1d

R13

b. 2 3 NC NC 2f

6

2g

7 8

R15-R22

Score Counter (tens)

1

1

16

Positive 5V–15V

1 output

2

15

Reset (when high)

0 output

3

14

Clock input

2 output

4

13

Inhibit (when high)

6 output

5

12

Carry

7 output

6

11

9 output

3 output

7

10

4 output

Negative

8

9

8 output

Negative

1

8

Positive 3V–15V

16

Trigger

2

7

Discharge

15

Output

3

6

Threshold

NC

Reset

4

5

Control

555

NC

15

5 output

13

2c

12

2b

11

2e

Clock input

1

16

Positive 5V–15V

10

2a

Inhibit (when high)

2

15

Reset (when high)

9

2d

Display Enable (when high)

3

14

Special output

Display Enable output

4

13

Output to c segment

12

Output to b segment

R14

c.

R23-R28

4026

3

Score Counter (units)

1 2

a.

4017

From Reset Button

From pin 3 of Burst Timer

1g

1c

Carry 10 output

5

1a

1e

Output to f segment

6

11

Output to e segment

1f

1d

Output to g segment

7

10

Output to a segment

Negative

8

9

Output to d segment

OR output

1

14

Positive 5V–15V

Input

2

13

NOR output

Input

3

12

Input

Input

4

11

Input

Input

5

10

Input

(Unused)

6

9

Input

Negative

7

8

(Unused)

1b

2c

d.

R13 and R14: 10K / R15–R28: 1.5K Score Counters: 4026 type

a

a

b

g

e.

e

D

Game Start button

a. 4017 decade counter. Reset and Inhibit pins are normally grounded. b. 555 timer c. 4026 decade counter with decoded 7-segment display outputs. Reset and Inhibit pins are nor-

Neg

c

d d

g e

g

f

F

a

f a

d Neg

b

b

e

f

f b

c d

2e

2g

c

2d

g

C

2f 2a

4078

2b

e c

mally grounded; Display Enable should be positive. d. 4078 8-input OR/NOR gate. e. Kingbright DC0411PBWA/A (blue) or DC04-11EWA (red) dual digit numeric display.

Game Timer Mole-zapping button NOR gate output Burst Timer Flash Timer

E

Fig. C: Lower half of schematic. Connect hookup wires between counter pins and display pins that have the same labels. Fig. D: A breadboarded prototype. Next step: Shift the components to perforated board and solder them into place, and mount push buttons and LEDs in an enclosure. Fig. E: This pulse diagram shows how the chips communicate. “Up” pulses are positive. “Down” pulses are negative. Fig. F: Pinouts of the chips used in this project. All components are viewed from above.

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