Fundamentals and Instruments 875
0V
0V
0V
1K0
D
1N4148
R^3 1K0
R^1
TH1
Output sinewave
TL071
Input
Y
X
C^2
R^2
R^4
R^5 R^6
RV1100 K
Vref Vref
D^2 Set mark tospace ratio
Voltage comparator
A^1
A^2
A^3
LM311
Square wave out
C^1
Op. amp.
Figure 30.1 : Basic Wien bridge oscillator and add-on square-wave gener
ator.