LVM-110 SIGNAL CONDITIONER
With DC Voltage Output
TE CONNECTIVITY SENSORS /// LIM-420 MANUAL 09290051-000 REV C 07/2016 Page 6
Setting the Amplifier Gain
Calculate the LVDT or RVDT full scale output, using the simple formula below:
LVDT/RVDT sensitivity (in V/V/inch or V/V/degree), at the selected frequency
multiplied with
The excitation voltage, (3 VRMS for the LVM-110)
multiplied with
The full scale of the LVDT in inches (or RVDT in degrees)
As an example, the calculation for an HR1000 LVDT (±1 inch range; 1 inch full scale), with a sensitivity of 0.39V/V/inch at
2.5KHZ, would be done as follows:
0.39 x 3 x 1 = 1.17 VRMS full scale output or 1.17 VRMS at ± 1 inch
Using the Gain Selection Table below, select the coarse gain settings (S1 and S2 DIP switches for the two amplification stages)
for the range the full scale output falls into. In our example, you would use the x0.2 HIGH, or the x0.5 LOW settings; either will
work, due to range overlap. The gain selections are for a ±10 VDC LVM-110 full scale output.
To calibrate the LVM-110 with your LVDT or RVDT for a ±5 VDC output, double the result of your full scale output calculation,
prior to consulting the gain table. This will result in you selecting half the normal gain, therefore half the normal DC output.
Gain Selection Table:
Calibration Procedure (for +/-10 and +/-5VDC Output)
Using the Connection Diagram in this manual, connect the LVDT or the RVDT, a DC voltmeter, and a bipolar power supply to
the LVM-110. Turn power on and allow 15 minute warm-up.
Note: Changing coarse gain settings (DIP switches) after Step 6 below may result in a zero shift. Should you find it necessary
to change the gain, you should repeat steps 1 through 6.
Step 1: Disconnect the LVDT/RVDT secondary lead-wire (black) from terminal 8
Step 2: Place a temporary shorting jumper across terminals 6 and 8 (to short the LVM-110 input)
Step 3: Adjust the ZERO potentiometer for zero volt DC output, between terminals 9 (GND) and 10 (OUT)
Step 4: Remove shorting jumper and reconnect the black wire to terminal 8
Step 5: Move the LVDT core or rotate the RVDT shaft to the approximate center of the mechanical range, then to the
transducer null (as close as possible to zero VDC output between pins 9 and 10)
Step 6: Using the ZERO potentiometer, adjust out any remaining output signal, due to positioning difficulty
Step 7: Using a gage block micrometer or other precision positioning device, displace the LVDT core or rotate the RVDT
shaft in a positive direction (positive DC voltage between pins 9 and 10) to the full scale position used in your
calculation (see “Setting the amplifier Gain”; +1 inch in our HR1000 LVDT example)
Step 8: Adjust the GAIN potentiometer for the required positive full scale DC output (5 or 10VDC) between pins 9 and 10
Step 9: Return to the original zero position to re-check your null DC voltage between pins 9 and 10
Step 10: Displace the LVDT core or rotate the RVDT shaft to the negative full scale position (negative DC voltage between
pins 9 and 10). You should measure approximately the same DC voltage (except negative) at this location as at
the positive full scale position.
