User manual

DBK16 Board Layout
AC Coupling, DC Coupling, and Low-Pass Filter Options
Headers on the board accommodate the coupling and low-pass filter options and the output channel
selection (see above figure). Resistors can be removed to lower filter gain from ×2 to ×1. A filter
frequency determining resistor network can be inserted into an IC socket.
The
AC or DC coupling choice (on each channel) is set by the presence or absence of a shunt jumper on
a two-pin header. If the shunt jumper is in place, the coupling is DC. If the shunt jumper is absent, the
coupling is AC. JP3 is used to configure the upper channel’s coupling; JP2 is used to configure the lower
channel.
The choice of
using or bypassing the low-pass filter (for each channel) is made by the orientation of
shunt jumpers on a 2×2-pin header. When the shunt jumpers are oriented in the same way as the “bypass”
symbol (horizontal, parallel with labels on card), the filter is bypassed. When the shunt jumpers are
oriented in the same way as the “filter” symbol (vertical), the filter is in the signal path. JP4 is used to
configure the upper channel; JP5 is used to configure the lower channel.
Frequency
Resistance
(Ω)
Bourns Part
Number
37Khz 10 4116R-001-100
19Khz 20 4116R-001-200
7Khz 50 4116R-001-500
3.7Khz 100 4116R-001-101
1.9Khz 200 4116R-001-201
700Hz 500 4116R-001-501
370Hz 1K 4116R-001-102
190Hz 2K 4116R-001-202
70Hz 5K 4116R-001-502
37Hz 10K 4116R-001-103
19Hz 20K 4116R-001-203
7Hz 50K 4116R-001-503
The corner frequency of the low-pass filters is determined by
three resistor values in each filter circuit. Located in the center
of the card, the lower channel resistors are R17-R18-R19; and
the upper channel resistors are R5-R6-R7. These resistor
locations are arranged to allow the use of an 8-position DIP
network (as a convenient means of changing all 6 resistors at
once). The machined-pin socket allows you to insert
individual resistors (should the two filter sections have
different corner frequencies). The table to the right lists
common frequencies, nominal resistance values, and Bourns
part numbers.
3.7Hz 100K 4116R-001-104
Note: Due to settling time, the filter should not be enabled during the DBK16 setup.
DBK16’s active low-pass filters have an inherent gain of ×2. You must factor this gain
into your setup calculations. To change the gain to ×1, remove the following 10 KΩ
resistors: R44 for the upper channel, R46 for the lower channel.
Reference Note: Methods of calibrating DBK16 are discussed in the calibration section.
DBK Option Cards and Module 879895 DBK16, pg. 7