NE556- SA556-SE556

6/8

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.

MONOSTABLE OPERATION

ASTABLE OPERATION

Output

Reset

Output

Control

f =

1.44

R + 2R ) C

B

A

Ground

Ground

0.01m F

C2

Control

Trigger

Threshold

1/2

NE556

SE556

+15V

Discharge

11

12

8

13

14

9

5

3

10

0.01m F

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

Output

R

1/2

NE556

SE556

A

(10)

(9)

(11)

(12)

(13)

7

5

2

1

4

14

3

6

(8)

C

Operating frequency

0.01nF

f =

1.44

R + 2R ) C

B

A

t2

t1