BRUEL & KJAER 2663, Technical Documentation Manual

Page: 26 / 54

Chapter 2 — Operation
Circuit Adjustment for Velocity Measurement
Preamplifiers Types 2663 and 2663 B
User Manual
BE 1068 – 12
19
Select the frequency
F
LP
at which the integration of the signal is to begin.
Thus a value for the resistance
R
L
can be found in the following formula (2.6.1).
(2.61)
A suggested value for the frequency
F
LP
at which integration begins is 10 Hz since
this will suppress any low frequency noise caused by transducer/temperature varia-
tions.
Fig.2.13 Resistor connections when using the preamplifiers as an integrator
2.6.2 Changing the High-pass Filter
The two resistors which determine the characteristics of the high-pass filter are
and .
The value of resistor is determined by the damping coefficient

and the cut-off
frequency F
HP
of the filter and is determined by the following formula:
Select a value for F
HP
= F
LP
= 10 Hz.
R
L
1.59 10
8

F
LP
--------------------------
  
=
R
H
1
R
H
2
R
H
2
R
H
2
 
2
1.2 + +
2

F
HP
C
---------------------------------
  
=