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Analog Relay Mux Board
Jumper W4 connects the AMPLOW to the ANALOG ground.
Pseudo differential inputs are referenced to AMPLOW. This
jumper can be used in conjunction to W3 to connect AMP LOW
to the system ground SYS GND.
__________________________
Low Pass Filter, R15 and C28.
The input to the programmable gain amp passes through a
low pass filter formed by R15 and C28. The nominal value of
these is R15 1k2 = 1200 Ohms, and C28 = 1.0uF. This produces
a time constant of approx 1/1000 second, cutting off signal
above 1kHz. To disable this remove C28 and short out R15.
R15 and C28 are located between the NMH1215 DC/DC
converter and the PGA202 amplifier. Just to the right of the
VOPT jumpers.
Gain Setting of Signal Amplifier.
____________________________ _
The PGA202 provides 4 jumper selected amplifications for
the signal before passing to the isolation amplifier.
The two GAIN jumpers are located in the centre of the
ADMUX card. The gain is the factor by which the input signal
from the on board relays or the CHAIN IN connection is
amplified by before isolation. The on board CJC compensation
produces a voltage of approx 10mV at room temperature, with a
gain of 100 jumper selected a 1 Volt signal is will be passed on
to the isolation amp and thence to the AD1200 card.
Reference
Page 11
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