Knowledge Base

The Soil Instruments Vibrating Wire Handheld Readout has been developed as a low cost vibrating wire and thermistor reader, to complement the company’s existing Portable Vibrating Wire Logger. The Soil Instruments Vibrating Wire handheld readout unit can be used to measure all Soil Instruments VW instruments. If you are experiencing issues with your readout unit can be taken to identify where the fault may lie.

2. Ensuring the correct sweep range is selected 

If you are receiving jumpy or highly variable readings, or your display is showing 'NO VIB WIRE' we recommend checking the sweep range you are using to take readings from the instrument. The Vibrating Wire sweep range selection is determined by the frequency range of the instrument you are reading.
This information is normally supplied in the instrument user manual or data sheet e.g. if the instrument has a specified frequency range of 1700 to 3000 Hz then select the smallest range that encompasses the instruments specified range.

If you do not know what type or what the specified frequency range is then set the sweep range to widest sweep range available and if the resultant reading is stable i.e. not changing by more than 1-2 digits, you can then set the sweep range to one which best covers this reading e.g. if the reading is 2500Hz then select the smallest sweep range that 2500Hz fits into allowing for future expected change in the instruments reading.

Handheld Readout
Sweep Range ID
Sweep Range Values
1
0450 - 1250 Hz
2
0800 - 2000 Hz
3
1400 - 3500 Hz
4
2400 - 6000 Hz

Sweep Range ID
Sweep Range Values
1
0202 - 1562 F²/1000
2
0640 - 4000 F²/1000
3
1960 - 12250 F²/1000
4
5760 - 36000 F²/1000
Table 1. VW Handheld Readout sweep ranges

If the instrument is wired in to the readout unit incorrectly this would normally result in the reading showing either 'NO VIB WIRE' or ‘NO THERMISTOR?’. If you are using the crocodile clips ensure that red is connected to red and the black crocodile clip to the black (or sometimes blue) sensor wire. The polarity of the thermistor wires (if fitted to the sensor), usually green and white, is not important, but for convention, white connect to white and green connect to green. Make sure that the wires and crocodile clips are lying so that they do not touch each other. If the vibrating wire circuit should ‘short’, the VW Readout will shut down to protect the circuitry.
If you believe the VW sensor was wired in incorrectly please correct the wiring and re-check the sweep ranges.

4. Checking the Batteries

Please ensure that the batteries within the unit are supplying sufficient power, if you believe that the voltage they are supplying may have dropped we would recommend replacing the batteries. The cover is removed by inserting a fingernail at the top of the clip and depressing it. The cover will unclip loose, then it maybe removed and put to one side. The battery compartment is now revealed. The four AA batteries may now be inserted between the terminals, ensuring correct orientation according to the clear markings beneath each battery location. Once located, the battery compartment cover may now be replaced. Make sure the light grey seal encircling the battery compartment has not been displaced from its groove. If so, push it back into place so that it is sitting evenly within the groove. Locate the lower end lug on the compartment cover into the compartment lower end slot and then push down the cover at its upper end until the clip ‘clicks’ clearly into place.
If you believe that the batteries we're effecting the reading quality of the unit please re-take steps 2 and 3.

If after completing all of the above processes you are still unable to take any readings using the readout we would recommend attempting to read further instruments with the readout unit or attempting to read the same instrument with a different readout. If you are able to read the same instrument successfully with a different readout you may need to return the possibly faulty handheld readout for inspection and repair.