Operating Instructions
422E5X Series
1.0 INTRODUCTION
The 422E5X series charge amplifiers
convert the high impedance charge
signal from a charge mode transducer to
a low impedance voltage signal.
This conversion is accomplished by the
use of a feedback capacitor across an
inverting amplifier (Fig 1). The gain of
the amplifier is sufficiently high to make
the charge amplifier gain virtually
independent of input capacitance
loading.
Fig 1
As in all charge amplifiers, the output is
inverting. Thus, any sinusoidal signal
will experience a 180 degree phase shift.
2.0 DESCRIPTION
The 422E5X series charge amps are .5
inch diameter by 3.4 inch long cylinders.
One 10-32 jack functions as input, one
BNC jack functions as output.
The amplifier operates on power
supplied by an ICP
®
power unit via a
simple two-wire coaxial cable.
During operation, the electrical charge
from the transducer is transferred to the
feedback capacitor, resulting in a voltage
given by the following equation:
V = Q/Cf
Q = the charge from the
transducer
Cf = the feedback capacitance
The accompanying 9V to 12V bias
voltage is typically removed by a 10uF
coupling capacitor internal to most PCB
ICP
®
power units.
A feedback resistor between 10
7
and
10
11
ohms (depending upon the specific
model) neutralizes unwanted, slowly
changing signal components resulting
from temperature effects and transistor
leakage. This resistor, along with the
feedback capacitor establishes the time
constant (low frequency response).
For low level measurements or remote
measurements over long cables, the
422E5X series improves the signal to
noise ratio and retains the high
frequency signal. The 422E5X series
requires little operator attention and
operates relatively drift-free in a
dynamic mode, an important
consideration in multi-channel
installations.
Содержание 422E5 Series
Страница 8: ......
