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LDC1000 Sensitivity of sensor

James Boehm
Prodigy 70 points
Other Parts Discussed in Thread: LDC1000EVM

I have created my own coil in a ferrite core and connected it to the LDC1000evm with a 20000pf cap. It works good but I am trying to get a good sensitivity on this so that it will detect a .003" change in distance.  I am using the GUI to see what it is doing and sometimes it changes within .003" and other times around .04".  Is there something I need to do to get the sensitivity better?

My coil is hand wound with 200 turns and is .68" od.

  

  • 0
    TI__Expert 6550 points

    Hello James,

    I would need more information to assist. What is the inductance of your coil? Are you using L measurement, Rp, or both?

    What is the distance between the taget and the coil? The target should be at least the same size as the coil, and the useful range of the distance between them is up to the 1/2 of the diameter of the coil. Also, what is the composition of your target?

    Please note that the EVM uses 6MHz reference clock. With the LDC1000, you can use up to 8MHz, which will increase your resolution.

    Best Regards,

    Natallia Holubeva

     

  • 0 in reply to Natallia Holubeva1
    Prodigy 70 points

    Thank you for your reply and I should have given you the GUI information as well.  I have to admit that I don't know much about the settings and how all this works but I have a general idea so forgive me if I don't understand something.

    This is the settings from the GUI. 1185.Mini.pdf

    OD of coil sensor is .66" and the GUI starts to detect around .292" from sensor using 16awg cold rolled steel 1.5" x 2.5" as target.  Is there a way to increase the distance as well?

    We make our own .5" OD sensors using a balanced pair which it will start to detect about 2" away but trying to balance the sensors has been a challenge.  This is the reason for trying the LDC1000 were we would not have to balance a pair of sensors.  The farthest the distance we need to sense would be around .75" and we could use a larger diameter coil but a larger coil makes for a larger sensing area.

  • 0 in reply to James Boehm
    TI__Genius 14270 points

    Hello James,

    The distance that the LDC can measure is based on the physical size of the magnetic field, which is based on the size of the inductor. A larger diameter inductor has a physically larger magnetic field. So increasing the outer diameter of the inductor will increase your sensing range.

    Please clarify the balanced pair of sensors you are currently using.

    Regards,

    ChrisO