12

ISO120/121

FIGURE 9. Right-Leg Driven ECG Amplifier (with defibrillator protection and calibration).

2

1

+

–

23

21

24

2

3

10

11

22

0.001µF

+V

S1

8

6

10

9

ISO

120

INA110

415

16

+V

S1

–V

SI

+V

S2

–V

S2

13

14

1

7

200k

Ω

200k

Ω

0.005 Power Resistor

120Vrms

100A

3

θ Y-Connected Power Transformer

C

1

–V

S1

912

V

OUT

C

2

C

1 = 1000pF

C

2 = 1000pF

Differential input accurately senses power resistor voltage.

Two resistors protect INA110 from open power resistor.

High frequency spike reject filter has f

CO = 400Hz.

FIGURE 8. Isolated Powerline Monitor.

15

4

7

5

6

14

+

–

37

40

38

39

1

2

21

22

18

19

20

23

24

4

3

PWS

726A

32

29

1

4

1

0.3

14

16

20k

Ω

20pF

–V

S1

+V

S2

20µH

+V

S1

+V

S1

–V

S1

–V

S2

+V

S2

C

2

C

1

Calibration Signal

5.00V

0V

1/2W

300k

Ω

50k

Ω

1/2W

300k

Ω

50k

Ω

1/2W

300k

Ω

180k

Ω

Calibration

On

Left Arm

On

Right Arm

Calibration

Right Leg

NE2H

NE2H

NE2H(2)

500pF

500pF

200pF

7

4

3

2

–V

S1

+V

S1

–V

S1

+V

S1

–V

S1

+V

S1

+V

S1

12

0.0082(1)

0.0082

–V

S1

9

8

10

11

13

5M

Ω

1k

Ω

1mV

Gain = 1000

17

ISO

121

INA102

OPA121

NOTE: (1) All capacitor values in µF unless otherwise

noted. Diodes are IN4148. (2) NE2H: Neon bulb, max

striking voltage 95V

AC.

6