7

Typical Applications

The sine wave output has a relatively high output impedance

(1k

Ω Typ). The circuit of Figure 6 provides buffering, gain

and amplitude adjustment. A simple op amp follower could

also be used.

With a dual supply voltage the external capacitor on Pin 10 can

be shorted to ground to halt the ICL8038 oscillation. Figure 7

shows a FET switch, diode ANDed with an input strobe signal

to allow the output to always start on the same slope.

To obtain a 1000:1 Sweep Range on the ICL8038 the

to nearly zero. This requires that the highest voltage on

few hundred mV. The Circuit of Figure 8 achieves this by

using a diode to lower the effective supply voltage on the

ICL8038. The large resistor on pin 5 helps reduce duty cycle

variations with sweep.

The linearity of input sweep voltage versus output frequency

can be significantly improved by using an op amp as shown

in Figure 10.

C81K

ICL8038

456

9

2

12

11

10

8

V- OR GND

3

V+

SWEEP

VOLTAGE

FIGURE 5B. CONNECTIONS FOR FREQUENCY SWEEP

FIGURE 5.

C

ICL8038

45

6

2

11

10

8

7

100K

V-

V+

AMPLITUDE

20K

+

-

741

4.7K

FIGURE 6. SINE WAVE OUTPUT BUFFER AMPLIFIERS

C

ICL8038

45

9

10

11

8

7

1N914

-15V

V+

STROBE

2

2N4392

1N914

15K

100K

OFF

ON

+15V (+10V)

-15V (-10V)

FIGURE 7. STROBE TONE BURST GENERATOR

0.0047

µF

DISTORTION

ICL8038

546

9

2

12

11

10

8

4.7K

-10V

3

+10V

20K

4.7K

1K

DUTY CYCLE

15K

1N457

0.1

µF

100K

10K

FREQ.

FIGURE 8. VARIABLE AUDIO OSCILLATOR, 20Hz TO 20kHzY

ICL8038