Audio Engineering

886 Chapter 30

Set duty cycle

RV1

1K0 R 3

4K7

R 4

4K7

R 6

10 K

RV5

100 K

RV4

100 K

R 5

10 K

C 4

C 3 4n7

4n7

R 1

22 K

10 K lin.

RV2

C 2

4n7

0V

RV31K

R 7 15 K D 1

VCC

Square-wave

Sinewave

Outputs

Triangular

Set frequency

(^4569)
3
2
10 11 12 1
8
7
Figure 30.11 : ICL 8038 application circuit.
With an input such as that shown in Figure 30.12(a) , an output waveform of the type
shown in Figure 30.12(b) would indicate a relatively poor overall stability by comparison
with that shown in Figure 30.12(c) , which would merely indicate some loss of high
frequency. The type of waveform shown in Figure 30.12(d) would imply that the system
was only conditionally stable and unlikely to be satisfactory in use.
The type of oscilloscope waveform shown in Figure 30.12(e) would indicate a fall off in
gain at low frequencies, whereas that of Figure 30.12(f) would show an increase in gain
at LF. Similarly, the response shown in Figure 30.12(g) would be due to an excessive HF
gain. With experience, the engineer is likely to recognize the types of output waveform