Microsoft LPF-00004 Manuel de l'opérateur télécharger pdf (Page 54)

Page 36 PRINCIPLES OF OPERATION

YBER

380, COPYRIGHT MARCH 2002, AXON INSTRUMENTS, INC.

Box 1

1) From Equation 2;

Gain V

−

Ω

2) For low values of R

, the 1 V

p-p

square wave drives an approximately 1 µA

p-p

current into the electrode. Thus the electrode resistance can be approximately

determined from:

Gain

=<150

ΩΩ

Giving R

= 1 kΩ for each mV at V

Figure 16. These graphs can be used to determine the electrode resistance measured during Electrode Test.

The solid line in Graph A represents equation 1 in the text. It reaches a maximum error of about 5% for

electrode resistances of 50 kΩ. The dotted line represents equation 2 and is accurate for all electrode values.

Graph B shows equation 2 over an extended range. These graphs assume that the CyberAmp is set for x1 total

gain, with one input grounded.

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Microsoft LPF-00004 Manuel de l'opérateur Page 54