BRUEL & KJAER 2663, Technical Documentation Manual

Page: 22 / 54

Chapter 2 — Operation
Circuit Adjustment for Acceleration Measurement
Preamplifiers Types 2663 and 2663 B
User Manual
BE 1068 – 12
15
In this application also,
(2.5.2)
To change the high frequency cut-off, exchange resistors and with resistors
of the value calculated by formula 2.5.2 above. As stated earlier, the cut-off frequency
is adjustable up to 200 kHz. Between 33 kHz and 200 kHz, the filter response is re-
duced. The response curve is shown in
section 3.2 and response curves obtained
using some typical resistor values are given.
2.5.3 Output Bias Adjustment
The output bias is preadjusted to 2.5 V and is also adjustable by replacing R
B
with a
resistor of the appropriate value. For a dual-polarity supply, this can be adjusted
from 0.0 to 5.5 V, referred to supply ground. For a single-polarity supply, the choice is
b0.5 and 5.5 V. The following formula is used to calculate
R
B
:
Thus the value for R
B
can be found:
(2.5.3)
To change the output bias, exchange resistor R
B
with a resistor of the value calculat-
ed from formula 2.5.3.
2.5.4 Sensitivity (Gain) Adjustment
The sensitivity, or gain, is preadjusted to 1 mV/pC and can be adjusted between 1
and 100 mV/pC. The formula printed on the circuit shield is as follows:
R
L
R
L
1
R
L
2
= =
R
L
1.59 10
8

F
LP
--------------------------
  
=
R
L
1
R
L
2
V
Bias
R
B
6.7

R
B
2 10
5

+
-------------------------------- V
 
=
R
B
V
Bias
2 10
5
 
6.7
V
Bias
–
---------------------------------------
  
=
Gain
1.69 10
5

R
G
10
3
+
--------------------------
mV
pC
--------- =