DOCUMENT 301900, REVISION D
EPISENSOR USER GUIDE 37
! The low-noise amplifier (selected by jumpers) provides a lower
noise output at the cost of additional power. This amplifier again
amplifies the signal by 1 or 4 to give a single-ended output of
either "2.5V or "10V.
! A second amplifier is also present which inverts the signal from
the first and can be connected to the negative output lead (via
jumpers). This allows the unit to give a differential "5V or "20V
to match the input to 24-bit digitizers.
Features
! Each EpiSensor module is equipped with a calibration coil.
Applying a current to this coil simulates the effect of an
acceleration applied to the sensor. This provides a much more
thorough check of the sensor's performance than older techniques
that merely stimulate the feedback circuitry.
! The calibration coils are open circuit in normal use to prevent cross
talk and noise pick-up. To utilize the calibration coil remotely from
outside the unit, the calibration coil enable signal must be activated
by applying a DC voltage of +5V to +12V with respect to ground.
! A voltage signal applied to the calibration line with CCE is active
will cause all three EpiSensor modules to respond with an
acceleration output of approximately 0.05 g per volt applied. The
exact calibration coil sensitivity is provided on the data sheet of
each module.
! This voltage mode will normally be used for checking the response
of the sensor remotely from a digitizer. If you wish to use a current
source to drive the calibration coils in a laboratory setting, they
may be accessed by removing the EpiSensor's case.
! All external connections are passed through double-stage transient
protection. This protection consists of a gas arrestor between the
line and protective ground. This is followed by a series impedance
and solid-state low-voltage transient protection device connected
between the line and protective ground.
! These elements protect the sensor from the effects of lightening
induced transients and electro-static discharge (ESD). Each line is
also filtered to prevent the entry of electro-magnetic interference or
radio frequency interference (EMI/RFI) to the sensor.
! Optionally, the unit can be equipped with a +12V to "12V
converter module allowing the EpiSensor to be powered from a
single 12-15V supply.
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