The Model 211 - EKG Amplifier Module is a state-of-the-art
device, featuring
protected high impedance buffered inputs. In addition to the
RA ( right arm), LA
(left arm) and LL (left leg) inputs, there is an Right Leg Ground
Driver. The
Ground Driver provides active noise suppression of low frequency
interference
signals by forcing the RL to ground reference potential. If the
subject is
accidentally exposed to a lethal voltage level, the RL Ground Driver appears as
a
high impedance and blocks the flow of a lethal current.
The input buffer outputs are connected to a Wilson summing matrix which
combines the
three basis electrical signals into leads I, II, II, aVR, aVL and aVF,
as selected on a
front panel rotary switch. The heart of the system is a precision
instrumentation
amplifier which has very high common mode rejection to minimize
the amplification of noise
pick-up.
The unit also features an Automatic Zero suppression circuit. Any one of three
different zero-level restoration time-constants may be selected on the front panel:
Slow,
Medium and Fast. These may be thought of as Diagnostic, Monitor Mode
and
Quick Restore, respectively. The module also has a spring loaded front
panel
Calibrate Button which causes a 1mv pulse to be superimposed onto the output
signal.
The noise suppression characteristics of this module are further enhanced by the
inclusion of two stages active notch filter. These narrow stop-band filters
provide
40 dB suppression at the line frequency and it's second harmonic. An
internal
switch selects 50 or 60 Hertz line frequency operation.
Copyright 1995 Triton Technology, Inc.
Updated March 28, 2006