offsetting voltages by using scaling_constant_tuner.vi

[Ronald]

Hi,

For some low frequency vibrations I'd like to use a DC-accelerometer +/- 2
g. Actual readings of the sensor (from -2 g till 2 g) are 0-10 volts. As
this is a DC-type at 0 g it reads out: 5 volt.

As the vibrations will not be more than app. +/- 0.2 g the voltage signal
will go between 4.5 and 5.5 volts.
I'm using a PCI-MIO-16E-4 board on which gains can be set to measure
between:
+/- 50 mV 0 - 100 mV
+/- 100 mV 0 - 200 mV
+/- 250 mV 0 - 500 mV
+/- 500 mV 0 - 1 V
+/- 1 V 0 - 2 V
+/- 2,5 V 0 - 5 V
+/- 5 V 0 - 10 V
+/- 10
V
The best resolution in this case is 0 - 10V, but that gives me very low
resolution.

Now here's my question: Is it possible to offset this voltage -5 volts by
using scaling_constant_tuner.vi and thus giving me the opportunity of using
gain and thus better resolution? Or should I offset this voltage by an
external (electronic hardware) device ??


Thanx,

Ron@ld

[Steve_M.]

Ronald,

To increase your resolution you need to get rid of the 5V offset. First, you need to use your card in differential mode. Connect the output of your sensor to CH+ and 5V to CH-. The 5V can be obtained by using 2 10k resistors to divide your 10V supply voltage. This should eliminate the offset and allow you to maximize your resolution.

Good luck,

Steve M.

[steveA]

the M is for "Money"