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SI-MT/SI-MKB/SI-HTB
WORLD PRECISION IN STRU MENTS
27
Calibration
Stand
Force
Transducer
Assembly
Tissue
Mounting
Hook
Fig. 22 When the force transducer is properly mounted in the calibration stand on the muscle
tester, the force transducer is held at the same angle used when making measurements.
3. Set
the
Gain
switch on the front panel of the
SI-BAM21-LCB
to the gain (X1-X10) that
is suitable for the mass being used for the calibration of the selected transducer.
4. With no weight suspended from the transducer, press and release the
Zero
button
on the
SI-BAM21-LCB
. Use the multimeter or data acquisition system to monitor
the transducer output signal from the
SI-BAM21-LCB
or the
SI-AOSUB
. A reading
of 0.0VDC ±50mV should be seen. Remember that the zeroing error is larger with
higher gains. Use the
Offset Adjustment
switch to move the baseline of the recording
closer to zero if a smaller offset error is desired.
NOTE
: When the
Zero
button is pressed, the zeroing LED illuminates to indicate that
the zeroing function is processing.
5. Use
the
Offset Adjustment
switch to adjust the baseline to zero. Press and hold the
toggle switch up, if you want to raise the baseline. Or, press and hold the toggle
switch down to lower the baseline. If the baseline is more than 0.3V above zero, the
High LED
illuminates, and if it is less than –0.3V, the
Low LED
illuminates. When the
baseline is within 0.3V of zero, the LEDs are off.
NOTE
: Once the baseline is zeroed to the desired position, do not touch the Offset
Adjustment switch until the calibration procedure is completed.
6. From the point on the tissue mount of the transducer where the tissue will be at-
tached, suspend a known mass that is close to the maximum range for the amplifi -
cation factor and force transducer being used. In the example for the
SI-KG4
force
transducer, a weight less than 5.0g is used for X1 or less than 0.5g for X10.
NOTE
: Mass in grams can be converted to force in Newtons (N) by multiplying the
weight hung on the transducer by gravitational acceleration. Since force equals mass
times acceleration (F=ma), a 0.5g weight is equal to 4.9mN (0.0005kg * 9.8m/s
2
=
0.0049N). Make sure that the mass used to calibrate the transducer amplifi er creates
a force that falls within the operating range of the force transducer and amplifi cation
factor you selected.
7. After the suspended mass becomes motionless, monitor the output of the amplifi er or
the corrected output of the anti-oscillation fi lter while adjusting the
Gain Calibration
potentiometer on the
SI-BAM21-LCB
. Use a potentiometer adjustment tool to adjust
the
Gain Calibration
potentiometer to any desired value up to the limit of 10.0V.