Welch Allyn PROPAQ CS Service Manual page 129

Service Manual Technical overview 125
spo2 block
PULSE OXIMETRY BLOCK DIAGRAM
AC COUPLED AMP
INTERNAL INVERTING AMP
SWITCH
PREAMP (VAR. GAIN STAGE)
PHOTODIODE
SIGNAL FROM
SENSOR
COMPARE 1
COMPARE 2
PEAK DETECTOR
PEAK DETECTOR
IR SIGNAL
SPLITTERS
FILTERS
DATA/CONTROLS
TO/FROM
ADC
SYNCHRONOUS
CPU
RED SIGNAL
DETECTOR
CAL
SIGNAL
TO SCP
BOARD
CPU
LED TO
CPU
CONTROL
DRIVERS LEDS
0696-73