NE556 - SA556 - SE556

Application information

9/16

Figure 14.

Tone burst generator

For a tone burst generator the first timer is used as a monostable and determines the tone

duration when triggered by a positive pulse at pin 6. The second timer is enabled by the high

output or the monostable. It is connected as an astable and determines the frequency of the

tone.

Figure 15.

Monostable operation

Output

Reset

Output

Control

f =

1.44

R + 2R ) C

B

A

Ground

Ground

0.01mF

C2

Control

Trigger

Threshold

1/2

NE556

SE556

+15V

Discharge

11

12

8

13

14

9

5

3

10

0.01mF

Ground

1/2

NE556

SE556

Trigger

Threshold

C1

Discharge

Trigger

Reset

Vcc

4

14

6

1

2

T = 1.1 R .C1

t

Output

R

1/2

NE556

SE556

A

(10)

(8)

(11)

(12)

(13)

7

6

2

1

4

14

3

C

10nF

(9)

5

Trigger

T = 1.1 R .C

A