Mallinckrodt Nellcor N-20 Service Manual page 70

VREF +12V
R63
7
2.0K
2
R160
3
51.1K
R23
R158
4 1
88.7K
.1%
1M -5V
8
6 7
U6D
LTC201
12 U1D
VREF
14
13
LF444
C40 R2
390PF
1M
R17 C1
3.32K
18PF
+12V
R1
4
182K
U1A 3
R58 1
9 11
3.32K 2
LF444
U6C 10
1
LTC201
1
-5V
TP44
SENSOR
INPUT
P1
L1
5
9
4
8
3
7
2
6
1
DB9F
TP78
R159
88.7K
.1%
5
U35
6
LT1097
SAMPRED
8
SAMPIR
OFF/ON
1
TP49
R26 82.5K
RED
3 2
U6A
3.32K
LTC201
C24
R19
.47UF
280K
C59
.047UF
VREF
VREF
1
R157
6
511K
R27
C22 14 15
.047UF
U6B
3.32K
LTC201
C25
.47UF
VREF
VREF
R57
40.2K
U9B
R56
3
5 PHOTOI
15.8K
4
LT1013
TP79
Differential Synchronous Demodulation Circuit
IR
Figure 9-9
9-33