BK Radio P150, Service Manual

Page: 253 / 264

BK Radio Page 7-3
integrated circuit data
integrator
An op-amp in which the only feedback element is a capacitor. The output of an integrator is a ramp, the
slope of which is determined by the amplitude of the steady input and the RC time constant.
R
C
-
Vin
Ov
Ov
VOUT
Zero crossing detector
The positive feed back path causes the output voltage to drive to the saturation potential of opposite
polarity as the input voltage. Ideally, the output switches from one saturation level to the opposite
saturation level as the input voltage passes through zero. Noise immunity demands the addition of RB
which requires that the input reach a certain magnitude after passing zero before the output will switch.
Vi
R
A
Vo
-
+
R
B
+
-
+
-
Vo
Vi
V
N
V
N
R
B
R
A
+ R
B
V
P
R
B
R
A
+ R
B
Vp
WHERE V
N
= MOST NEGATIVE Vo
V
P
= MOST POSITIVE Vo