New strain gauge data logger from Windmill Software

Just connect your strain gauges to the strain box, plug the box into the 851 data logger and it is ready to use. This method of connection means you can use the 851 data logger to monitor, for example, temperature at the same time as strain.

With the 851-SG package you can monitor strain gauge bridges and balanced bridges such as pressure transducers. You can also configure individual channels to accept any of these inputs:

-voltage
-quarter bridge: single strain gauge
-half bridge: tensile + compressive strain gauge
-half bridge: normal + transverse strain gauge
-full bridge: 2 tensile + 2 compressive gauges
-full bridge: 2 normal + 2 transverse gauges
-full bridge: tensile normal + compressive normal + tensile transverse + compressive transverse gauge

Strain gauges need an external excitation voltage to supply sufficient current to keep all the bridge circuits energised. The 851-SG package provides four sets of 16 screw terminals giving + and - excitation and signals for each of 16 bridges. Two 1kOhm termination resistors are mounted in half bridge configuration whilst high quality 350 and 120 -Ohm resistors can be provided for the completion of quarter bridges. 

When a bridge input is selected the Windmill software monitors excitation voltage and performs the bridge calculation to produce a reading in micro strain. This eliminates errors due to changes in excitation voltage. 

The initial unstrained bridge measurement is often much larger than the change in signal due to strain. If this initial value is not accounted for, it restricts the resolution you can obtain (the smallest signal you can measure).

Windmill software can zero or balance the bridge, nulling the offset of the initial voltage. So instead of measuring over a wide range - 0 to 0.5V, for example - you can choose a narrow range such as 0 to 0.01V. 

Each range is divided into a fixed number of steps. The smaller the range and the larger the resolution, the more precise the reading. The 851-SG offers a choice of resolutions from 12-bit for fast sampling to 18-bit for greater precision.

The units cost £775 each, excluding VAT.