LINEAR RAMP

cuit is replaced by a constant current source, a linear

ramp is generated. Figure 17 shows a circuit con-

figuration that will perform this function.

Trigger

Output

C

NE555

2

4

3

1

5

6

7

8

E

0.01

R2

R1

R

2N4250

or equiv.

Figure 17.

Out

C

NE55

2

4

3

1

5

6

7

8

51k

Ω

22k

Ω

0.01

µF

0.01

µF

Figure 19 : 50% Duty Cycle Oscillator.

Figure 18 shows waveforms generator by the linear

ramp.

The time interval is given by :

T

Figure 18 : Linear Ramp.

Top trace : input 3V/DIV

Time = 20

µs/DIV

Middle trace : output 5V/DIV

Ω

Bottom trace : output 5V/DIV

Ω

Bottom trace : capacitor voltage

Ω

1V/DIV

C = 0.01

µF

50% DUTY CYCLE OSCILLATOR

be connected as in figure19. The time preriod for the

output high is the same as previous,

[













Thus the frequency of oscillation is f

=

1

comparator.

ADDITIONAL INFORMATION

Adequate power supply bypassing is necessary to

protect associated circuitry. Minimum recom-

mended is 0.1

µF in parallel with 1µF electrolytic.

NE555/SA555/SE555

8/10