R2

10K

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

R4

499

+5 V

+2.5 V

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

R1

10K

Sq. wave~1 kHz

Red LED

Pulse OX probe

+5 V

LEDLED

IR LED

+2.5 V

C2

0.47uF

R3

1k

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

photodiode

+2.5 V

PD-

R5

1M

+5 V

PD+

Pulse OX probe

Detectorsignal

20K

20k

20K Vout

From photodector

From oscillator

output

Sw A IN

(pin 1)

SigA out

(pin 2)

+5 V

Control A

(pin 13)

CD4066B

+2.5 V

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

+5 V

0.1 uF

0.1 uF

+2.5 V

100k

+2.5 V

0.1 uF

+5 V

1M

1k

Pulse

1 uF

Low Pass Filter

From +1/-1multiplier

100k

499K

+2.5 V

100k

Low Pass Filter& Amplify

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

+5 V

1 uF

Oxygencontent

Long time

constant low

pass filter

100k

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

High PassFilter

U2A

LMC6484

1

3

2

411

OUT

+

-

V+

V-

Figure 7: On the left is the pulse signal. On the right is a test where the subject held their breath after 10 seconds. They held their breath for about 1 minute and then began breathing (heavily).

0 2 4 6 8 10-0.1

-0.05

0

0.05

0.1

0.15

time (s)

V (

puls

e)

0 20 40 60 80 100-0.04

-0.02

0

0.02

0.04

0.06

0.08

time (s)

V (

~oxygen c

onte

nt)