7)
With the port B stop-cock set to atmosphere, adjust the NL108A ZERO ADJ front panel potentiometer
so the 0V is recorded at the OUT sockets. (CALIB switch in OFF position and the pressure range toggle switch
in the 1.0V = 100mm position). Now switch the port B stop-cock so that the column of water is connected to the
transducer. The output of the NL108A should give an output of +1.0V, if the excitation voltage and sensitivity of
the transducer are correct. If not, check the BRIDGE VOLTAGE setting again (also double check the
transducer data sheet).
8)
Deviations from 1.0V output (for the 1.36m pressure) can be adjusted with the trimmer on the NL108A
printed circuit board labelled GAIN. Small adjustments can also be made with the BRIDGE VOLTAGE setting -
but be careful not to exceed the limits for your particular transducer.
9)
When correctly set up, pushing the OUT GND push-button should produce the same effect on the
output as opening port B to the atmosphere. Switching the CALIB toggle switch to its 1.0V position should also
produce the same output deflection as opening port B to the 1.36m column of water.
10)
Steps 6 and 9 can be repeated for the 100mV = 1cmH
2
O switch position. In this case, however, the
column of water should be 10cm for 1.0V output deflection.
USE OF THE OUT GND AND CALIB SWITCHES
The OUT GND push-button is used to locate the zero pressure dc level on the output recording (some chart
recorders drift!). A 0.0V to 1.0V calibration deflection is produced on a recording trace by switching the CALIB
switch to 1.0V and pushing the OUT GND push-button a couple of times. Similarly for the 0.0V to 100mV
calibration deflection.
Specification
Input voltage range
: ±15V
Gain
: 1V/100mmHg or 100mV/cmH
2
O
(for a pressure transducer having an output of 50µV/mmHg)
DC offset
: ±60cmH
2
O or ±40mmHg
(when switched to the appropriate range)
Bandwidth
: DC - 150Hz
O/P voltage range
: ±12V
O/P impedance
: 600ohms (nom)
except 'zero out', where O/P is s.c to ground
Bridge supply
: 0-24V dc (25mA)
First Issued:
before July 1984
Last Revision:
October 18, 2000
Printed:
October 18, 2000
File Reference:
N:\DOCS\COMPANY\MANUALS\NEUROLOG \ NL108A.SAM
Users Manual
NeuroLog™ System
NL108A
Digitimer Ltd
Page 3 of 3
Copyright © 1996-2000
E-mail:
Tel:
+44 (0)1707 328347;
Fax:
...373153
Website:
www.digitimer.com
