untitled

Resistors R1, R2, and R3limit the current running to ground when you

press switches S1, S2, or S3.

C2, C3, C4, and C5are capacitors that fill a function that the Max232

designers call charge pump capacitors.These are required to make the

IC2 function properly.

3

2

6

5

4

IC 3

C 8

C 9

C 10

R 8 +

• 
  

+

+4.5 V

15

2

7

4

1 10

2

1

3

6

15

5

4

16

R6 R7

18

14

11

12

13

5

3

6

8

9

14

13

8

3

+

+

11

12

+

+

+ 4.5 V

S 1 S 2 S 3

R1

R2

R 3

R4

R 5

+

C 1

C 2

C 3

C 4

C 5

5

C 6 C 7

IC 1 IC^2

+

+

C 11

R 9

7

Figure 7-2:

The

schematic

of the

talking

puppet

circuit.

142 Part II: Sounding Off!