Ideal for linear control and precision measurement applications, the Subminiature DVRT® provides fast response and rugged packaging. The Subminiature DVRT® features micron resolution, linear analog output, flat dynamic response to kHz levels, and very low temperature coefficients. Its free sliding transducer core is lightweight, strong, and corrosion resistant. Cores are precision ground to insure a close sliding fit within the open bore of the stainless-steel lined DVRT® body. This precision allows the DVRT® to achieve extremely high repeatability. The sensing head is capable of total submersion in aqueous environments.

Datasheet

High Performance

  • Sub-micron resolution with large stroke/size ratio
  • Frictionless design for robust use over millions of cycles
  • Suitable for use in harsh fluids and environments
  • High dynamic range for difficult measurements

Ease of Use

  • Plug and play usability
  • Easily customized to suit specific requirements
  • Signal conditioning options for any application

Electrical Specifications
Obtained using DEMOD-DVRT® and DVRT® with 800 Hz low pass filter at constant temperature

Linear Stroke Lengths 4, 8, 24, 38 mm (standard resolution)
6 mm (high resolution)
500 µm or less (nano resolution)
Accuracy ± 1.0 % using straight line
± 0.1 % using polynomial
Sensitivity DEMOD® output / sensor range
Signal to noise 4200 to 1 (with filter 3 dB down at 800 Hz, standard resolution), 466 to 1 (unfiltered)
Resolution 1.0 µm for 4 mm stroke
2.0 µm for 8 mm stroke
6.0 µm for 24 mm stroke
9.5 µm for 38 mm stroke
0.6 µm for high resolution version
125 nm for nano resolution version (up to 10 nm resolution is possible with customized sensor range and electronics)
Frequency response 800 Hz standard, 20 KHz optional
Temperature coefficient offset 0.002% / ˚C (typical) span 0.030% / ˚C (typical)
Hysteresis ± 1 micron
Repeatability ± 1 micron

Mechanical Specifications

Overall body length 18.5 mm for 4 mm stroke
34.5 mm for 8 mm stroke
81 mm for 24 mm stroke
110 mm for 38 mm stroke
34.5 mm for high res version
34.5 mm for nano version
Outside diameter 4.76 mm (3/16 inch)
Housing material

300 stainless steel, smooth;
5/16 - 24 UNF threaded 400 stainless steel (optional);

M8x1.25-6g threaded 400 stainless steel (optional)
Attachment method optional: magnetic mounting block, threaded body, clamping collar
Leadouts 45 cm multistrand, shielded, stainless steel reinforced teflon insulated cable
Connector keyed 4 pin Lemo, polyolefin relief
Operating temperature -55 to 175 ˚C
Core weight 500 µm: 0.4 g, 4 mm: 0.4 g, 6 mm: 0.4 g, 8 mm: 0.4 g, 24 mm: 1.62 g, 38 mm: 1.67 g
Core material stainless steel
Cable diameter 0.070 “

Contact us for information on custom designs suitable for immersion, corrosive and high pressure environments.

There are no downloads for this product.

As an example. here is the Quick Start Guide for the M-DVRT-9: http://files.microstrain.com/Micro_Sub_DVRT_Quick_Start_Guide.pdf

Page 7 refers to the Slope and Offset that you will need to enter into the Smart Motherboard software.

In the Smart Motherboard software, click Tools.

Click Configuration and the Configuration screen appears.

Select the appropriate channel (remember that each channel, i.e., each DVRT and DEMOD –DVRT signal conditioner card in the Smart Motherboard is calibrated separately) by checking the Channel check box.

Select the Linear Radio Button.

Enter the Slope and Offset in the number scroll boxes.

Select None in the Peak Detect drop-down.

Change the Units from Volts to mm (for millimeters) by wiping through with your mouse.

Click File.

Click Save As Default.

Click File.

Click Return and you are ready to sample in millimeters.

Yes, but you must be sure to cut the correct end or the plunger will not work and must be replaced.

1.       The M-DVRT plunger has a smaller diameter wire protruding from the end that is not inserted into the DVRT body.  This is the end that can be cut.  Another way to determine the correct end is to insert the plunger into the DVRT and observe the output.  If you get an output change, do NOT cut that end, as it is the end with the ferrite, and the plunger will no longer work if this end is cut.  You can use a pair of wire cutters to cut the M-DVRT plunger.

2.       The S-DVRT plunger looks like it is plugged at one end and hollow at the other end.  The plugged end is the end with the ferrite: do NOT cut that end.  Again, another way to determine the correct end is to insert the plunger into the DVRT and observe the output.  If you get an output change, do NOT cut that end, as it is the end with the ferrite, and the plunger will no longer work if this end is cut.  You can use a dremel tool to cut the S-DVRT plunger.

When cutting the plungers, keep in mind that you want some length of plunger protruding from the DVRT for mounting when it is fully compressed.

In order to return any LORD MicroStrain® product either for repair or return, you must contact us for a Return Merchandise Authorization number (RMA). If you purchased directly from LORD MicroStrain® in the United States, please contact your Sales or Support Engineer to obtain an RMA.  If you purchased directly from a LORD MicroStrain® distributor, please contact your distributor to obtain an RMA.

If you are located in the United States, LORD MicroStrain® supplies you directly.  If you are in located in another country, LORD MicroStrain® products are available exclusively from LORD MicroStrain® distributors.  Please use this locator to determine your distributor: http://www.microstrain.com/support/international

LORD MicroStrain® Support Engineers are always available to support you in any way we can by phone, email, SKYPE or Live Chat from our home page.  Contact details may be found at: http://www.microstrain.com/support/contact-support

LORD MicroStrain® insures all products shipments to their full value unless the customer specifically states a different method.

LORD MicroStrain® warrants its standard products to be free from defective material and workmanship for a period of one (1) year from the original date of purchase.  Warranty details may be found at: http://www.microstrain.com/support/warranty

If you are using the standard cable type supplied with the DVRT sensors, 20 feet is the maximum for M-DVRT and MG-DVRT, and 60 feet is the maximum for S-DVRT, SG-DVRT and NC-DVRT. If you require longer cable lengths, LORD MicroStrain® can provide custom cables of lower resistance.

No, carbon fiber has not been shown to pose a problem.

Yes, as a courtesy, LORD MicroStrain® will provide an appropriate drill bit and tap to match the DVRT's thread size at a nominal charge.

In most cases, MicroStrain calibrates every DVRT with its accompanying electronics and provides a detailed calibration certificate. The certificate provides 3 methods of calibration and all the particulars including formulas to resolve voltage into engineering units.

  • Standard Least Squares Linear Fit provides a simple mathematical method to convert sensor output to displacement and delivers reasonable accuracy.
  • Polynomial Fit provides a more mathematically intensive method to convert sensor output to displacement and in turn delivers a high degree of accuracy. A possible drawback to some users of this method may be that it can not accurately report measurements beyond its stroke length (i.e., over-stroking).
  • Multi-Segment Linear Fit provides the most mathematically intensive method to convert sensor output to displacement, delivers a high degree of accuracy and is not subject to the drawback of over-stroking.
  • Body length to stroke ratios for DVRTs are typically 2.5 to 1 as compared to 6 to 1 for LVDTs.
  • Microminiature DVRTs are available in body diameters of only 1.5 mm (.060") and with core diameters of only 0.5 mm (.020"); this makes them the World's smallest commercially available linear displacement transducers.
  • DVRTs maintain their temperature stability due to the use of two coils arranged differentially.
  • Each DVRT is capable of submersion as a standard feature.
  • Each DVRT can be hermetically sealed as an option.
  • Microminiature DVRTs are available with super-elastic, nickel titanium cores.
  • DVRTs have a standard operating temperature range up to 175 degrees C; LVDTs typically only operate up to 85 degrees C.
  • DVRTs have been operated successfully in liquid nitrogen; LVDTs typically only operate to -20 degrees C.

The output is an analog DC voltage proportional to linear displacement.  The full scale voltage is optionally +/-5 volts or 0-10 volts.  The analog voltage is easily read using a multi-meter or DAQ.  The voltage can also be read in the digital domain by using LORD MicroStrain® Smart Motherboards.  These Smart Motherboards provide a data gateway to PC-based software or to user-programmable LCD displays on the motherboard itself.

Yes. DVRTs can be used in wet environments.  One of our customers uses the DVRT to measure mussel growth on the ocean floor.  An automotive customer uses the DVRT in a hot oil environment for under-the-hood testing.  Our orthopaedic customers use the DVRT for soft and hard tissue testing (in vivo and ex vivo) in cadaver and animal studies.

Sandard DVRTs can operate up to 100 PSI.  However, custom-designed sensors have been used in applications up to 10,000 PSI.  Please contact your sales or support engineer for more info.

Typically, every DVRT is calibrated at the factory with its accompanying DEMOD signal conditioner.  The calibration is made over the entire system (DVRT and DEMOD) to insure the highest accuracy.  DVRTs and DEMODS are color-coded to insure that they stay together as a pair when in use.

The term ‘Motherboard’ refers to the LORD MicroStrain® DEMOD-DVRT or DEMOD-DVRT-TC signal conditioner mounting chassis.  The standard Motherboard provides a mounting slot and power to the individual DEMODs.  The Smart Motherboard provides a mounting slot, power and digital communications (RS-232) to the individual DEMODs.  Both Motherboard and Smart Motherboard provide analog ouput to a DAQ.  In addition, Smart Motherboard provides digital output to a computer.  Motherboards and Smart motherboards can accommodate 1 to 8 DEMOD cards.

DVRT Type Threaded Core Threaded Body Core Clamps Body Clamps SM-Block Core/Body Magnetic Mount Core/Body
Subminiature X X     X X
Subminiature Gauging X X        
Microminiature X X X X    
Microminiature Gauging X X   X    
Non-Contact   X**        

** Non-Contact comes standard with threaded body except for 5.0.

 

In a word, no. The design of an LVDT’s coil forms a Wheatstone full bridge and the design of LORD's DVRT coil forms a Wheatstone half-bridge. LORD MicroStrain® signal conditioning electronics are designed for the half-bridge.  Likewise, a DVRT can not use a LVDT's signal conditioning electronics.

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